# Hongbai Technology - Site: https://www.hongbaiweld.com/ ## Lift Height in Drawn Arc Stud Welding: Why Is 1.0–1.5 mm Commonly Recommended? - Link: https://www.hongbaiweld.com/news/interior-accessories4184.html - Published: 2026-11-13T16:18:57+08:00 - Author: zhouhui _Understanding the relationship between lift height, arc voltage, welding energy, and equipment settings._ ## 1. What Is 󠀁[Lift Heigh](https://www.hongbaiweld.com/tag/350)󠁿t in Drawn Arc Stud Welding? Lift height is a key process parameter in drawn arc [stud welding](https://www.hongbaiweld.com/tag/145). It refers to the distance the welding gun lifts the stud from the workpiece at the beginning of the welding current stage. The drawn arc stud welding process consists of four stages: 1. **Short-Circuit Stage** – The stud contacts the workpiece, completing the electrical circuit. 2. **Pilot Current Stage** – A pilot current is applied to initiate the arc. 3. **Welding Current Stage** – At the beginning of this stage, the welding gun lifts the stud to a preset distance from the workpiece. This distance is the lift height. The main welding current then maintains the arc and melts the stud end and the corresponding area of the workpiece. 4. **Upset Current Stage** – The stud is plunged into the molten pool. The power source continues to apply current to the workpiece, reducing the cooling rate and helping maintain the plasticity of the joint to form a sound and reliable connection. Lift height is therefore more than a mechanical position setting. It directly affects the arc voltage during welding and, consequently, the energy delivered to the joint. ## 2. How Does Lift Height Affect 󠀁[Arc Voltage](https://www.hongbaiweld.com/tag/351)󠁿 and Welding Energy? In drawn arc stud welding, lift height directly influences the arc voltage. According to the SAW3600R series technical documentation, increasing the lift height raises the arc voltage. When welding current and welding time remain unchanged, a higher arc voltage results in greater energy input. This relationship can be understood through Joule’s law: the electrical energy converted into heat depends on current, arc resistance, and the duration of current flow. Arc voltage reflects the arc resistance in the welding circuit and is therefore an important factor affecting energy output. For the relevant Hongbai equipment models, actual arc voltage is an important process parameter and a key factor in welding quality control. The expected arc voltage reference of 20–26 V is specified in the technical documentation for the relevant model. This range should be applied according to the corresponding equipment requirements rather than treated as a universal value for all models. ![Four stages of drawn arc stud welding: short-circuit, pilot current, welding current, and upset current.](https://www.hongbaiweld.com/wp-content/uploads/2026/11/2026111209202775. png) ## 3. Why Is the Expected Arc Voltage a Passive Parameter? The expected arc voltage is a reference value used by the welding system. The actual arc voltage is primarily determined by the lift height during the welding process. The two parameters are therefore not set independently of each other. Lift height is set first, and the actual arc voltage follows from the resulting arc condition. The system measures the actual arc voltage and uses it as a basis for monitoring and compensation. It does not independently establish the arc voltage regardless of the mechanical lift height. In practical terms, arc voltage is the resulting value, while lift height is the parameter that directly determines it. Arc voltage records can therefore provide a measured indication of how the lift-height setting performs during individual welds. ## 4. Why Is 1.0–1.5 mm Commonly Recommended? A lift height of 1.0–1.5 mm is commonly used as a reference setting for several drawn arc stud welding systems. This range provides a practical starting point for setting up the welding process. However, the appropriate value depends on the equipment model and the actual welding conditions. The reference range should not be treated as a universal setting for every machine or application. For thin-sheet applications, reducing arc voltage is beneficial. For T-type studs welded onto approximately 0.6 mm sheet, a lift-height reference of 0.6–1.0 mm may be used. The equipment-specific ranges and reference values are listed in Section 6. ## 5. Lift Height and Plunge Depth: Two Different Parameters Lift height and plunge depth are two separate process parameters. They act at different points in the welding process and serve different purposes. ![Technical comparison of lift height and plunge depth in drawn arc stud welding, showing stud positions, downward travel during upset, and weld flash.](https://www. hongbaiweld.com/wp-content/uploads/2026/11/2026111308072363.png) ### Lift Height (Pos1) Lift height determines how far the stud is lifted from the workpiece at the beginning of the welding current stage. It affects the arc voltage and, in turn, the energy delivered during welding. ### Plunge Depth (Pos3) Plunge depth determines how far the stud is plunged into the workpiece during the upset stage. An excessively high Pos3 setting causes the stud to contact the base material too quickly and strike into the molten pool, resulting in increased spatter. If Pos3 is set too low, the stud remains floating above the base material, which can result in a cold weld. Lift height and plunge depth must therefore be considered separately when setting and evaluating the welding process. ## 6. Lift Height Parameters for Different Hongbai Equipment Models Lift-height ranges and reference settings vary by equipment model. The following values are based on the technical documentation for the relevant model. | Equipment Model | Lift-Height Range | Reference / Default Setting | | SAW3600 Series | 0.7–4.0 mm | 1.0–1.5 mm | | SAW3600C | 0.5–4.0 mm | 1.0 mm | | PIDS | 0.2–3.0 mm | 1.2 mm | | HEAS | 0.5–4.0 mm | 1.0–1.5 mm | For the HEAS system, Pos1 is displayed in millimetres, with a setting precision of 0.01 mm. The return distance of an electromagnetic welding gun is a separate parameter, with a reference range of 0.5–1.2 mm. It should not be confused with the dynamic lift height during welding. ## 7. Arc Voltage Deviation Compensation Some Hongbai welding systems provide arc voltage deviation compensation. The system determines whether the actual arc voltage falls within the specified deviation from the expected arc voltage. When the deviation exceeds the set range, the system automatically compensates the welding current to maintain the output energy as far as possible. The relevant settings are as follows: | Parameter | Default Value | Setting Range | | Arc Voltage Deviation | 1.0 V | 0.1–2.0 V | | Current Deviation | 100 A | 10–200 A | These values are equipment settings. Their availability and applicable ranges should be checked against the technical documentation for the relevant model. ## 8. Lift Height Must Match the Equipment and Welding Conditions Lift height is the first control point in this energy relationship — the arc voltage and energy input that follow are directly related to this setting. The 1.0–1.5 mm range is a useful reference for many applications, but the final setting must be selected according to the equipment model and the actual welding conditions. When evaluating a welding process, lift height, actual arc voltage, welding current, welding time, and plunge depth should be considered in their respective roles. Equipment- specific documentation should always take precedence over general reference values. Hongbai manufactures drawn arc stud welding equipment and control systems for automotive manufacturing, general mechanical manufacturing, shipbuilding, and structural and civil engineering applications. ## SAW-D9 Arc Drawn Capacitor Discharge Stud Welder - Link: https://www.hongbaiweld.com/all-product/robot-series/stop-tail-lights4122.html - Published: 2026-11-06T13:24:00+08:00 - Author: zhouhui ## Key Features **Three Welding Processes** Supports drawn arc, contact and non-contact stud welding. **Three Independent Welding Channels** One main unit supports up to three welding channels with different gun and process configurations. **Post-Weld Tempering** Applies a controlled current after capacitor discharge to slow cooling and help reduce thermal stress. **Online Capacitor Monitoring** Calculates capacitor capacity after each welding cycle to identify aging and support equipment maintenance. **Flexible Gun Configurations** Compatible with servo and non-servo welding guns, including automatic, semi-automatic and manual servo configurations. **Industrial Communication** Integrated PROFINET and DeviceNet interfaces, with multiple Ethernet ports for PC, CNC and PLC communication. **Welding Data Management** Integrated oscilloscope, data logger and WeldNIC group control software support waveform analysis, process monitoring and equipment management. ## Welding Process and Digital Control The [SAW-D9](https://www.hongbaiweld.com/tag/343) supports three welding process categories: drawn arc, contact and non-contact welding. Servo-controlled guns provide precise control of stud movement and contact force, while non-servo configurations offer a simpler equipment structure. Its post-weld tempering function maintains a current output of approximately 50– 100 A after the main discharge, helping control the cooling process and reduce the risk of cracking under suitable welding conditions. For equipment condition monitoring, the system records discharge voltage and current waveforms at a 100 kHz sampling rate and calculates capacitor capacity using an integration algorithm. This provides ongoing information about capacitor condition. ## Digital Monitoring and Automation Integration The SAW-D9 incorporates an X86 / Windows-based data logging platform with 1 TB or greater storage capacity and support for more than one million welding-point records. Welding data is stored in a MySQL database and can be exported in CSV format for further analysis. Multiple Ethernet ports provide dedicated communication functions for PC monitoring, real-time data, data logging, Modbus TCP and CNC control. PROFINET and DeviceNet interfaces support integration with industrial automation systems. Through WeldNIC group control software, up to 250 devices can be managed within one network, with functions including event monitoring, fault recording, parameter backup and historical data management. The system can also connect with MES and other production information networks. ## Typical Applications The SAW-D9 is suitable for capacitor discharge stud welding applications in: * Automotive sheet metal and body components * New energy vehicle structural parts * Electrical cabinets and metal enclosures * 3C electronic equipment housings * Industrial sheet metal fabrication * Automated stud welding production lines ## Technical Specifications | Category | Technical Specification | | Model | SAW-D9 | | Equipment Type | [Digital Capacitor Discharge Stud Welding Machine](https://www.hongbaiweld.com/tag/344) | | Welding Processes | Drawn Arc, Contact, Non-Contact | | Welding Channels | 3 independent channels | | Welding Gun Types | Servo and non-servo welding guns | | Servo Gun Modes | Automatic, Semi-Automatic, Manual | | Post-Weld Tempering Current | 50–100 A | | Drawn Arc Current | 10–100 A | | Servo Gun Lifting Distance | 0.5–5 mm | | Non-Contact Position Holding Time | Approximately 20 ms | | Capacitor Monitoring | Online capacity calculation after welding | | Waveform Sampling Rate | 100 kHz | | Industrial Fieldbus | PROFINET / DeviceNet | | Ethernet Communication | Multiple ports | | Ethernet Protocols | Modbus TCP, RTD and dedicated PC, data logger and CNC interfaces | | Data Logger Platform | X86 / Windows | | Data Storage | 1 TB or larger | | Welding Data Capacity | More than 1 million welding-point records | | Database | MySQL | | Data Resolution | 10 μs | | Data Export Format | CSV | | Oscilloscope Resolution | 16-bit | | Oscilloscope Channels | 16 channels (subject to final technical confirmation) | | Group Control Software | WeldNIC | | Network Management Capacity | Up to 250 devices per network | | MES Integration | Supported | For application-specific requirements, please contact Hongbai for technical consultation and welding process evaluation. ## Global Distributor Recruitment | Become a Hongbai Partner - Link: https://www.hongbaiweld.com/news4098.html - Published: 2026-11-06T09:57:23+08:00 - Author: zhouhui **Industrial Welding Equipment | Automation Solutions | Global Distribution Partnership** ## 1. Expanding Our Global Distribution Network As manufacturing processes become increasingly automated, the requirements for welding equipment extend beyond basic functionality. Production efficiency, process consistency, equipment reliability, and system integration have become important considerations for manufacturers across the automotive and industrial sectors. Since 2003, Shenzhen Hongbai Technology Industry Co., Ltd. has specialized in the development and manufacturing of intelligent welding equipment and industrial automation systems. Our product portfolio covers stud welding, resistance spot welding, electrode cap dressing and changing, and automated welding solutions. With established engineering and manufacturing capabilities, Hongbai serves customers in automotive manufacturing and other industrial applications. To support our continued international development, we are seeking qualified distributors and industrial partners in selected markets. We welcome companies with relevant industry experience, established customer relationships, and the technical and commercial capabilities required to develop their local markets. ## 2. About Hongbai Hongbai is an industrial welding equipment manufacturer with more than 20 years of experience in welding technology and automation. Our capabilities encompass equipment development, manufacturing, application engineering, and customized system integration. We work with customers to address practical production requirements, ranging from individual welding equipment to integrated automated workstations. ![](https://www.hongbaiweld.com/wp-content/uploads/2025/06/2025061315412468-e1749829505483. jpg) Our core product and technology areas include: ### 󠀁[Stud Welding Systems](https://www.hongbaiweld.com/tag/341)󠁿 Intelligent stud welding equipment designed for manual, semi-automatic, and robotic applications across automotive and industrial manufacturing. ### 󠀁[Resistance Spot Welding](https://www.hongbaiweld.com/tag/228)󠁿 Solutions Spot welding equipment and automated welding systems designed to meet the requirements of automotive body and component manufacturing. ### 󠀁[Electrode Cap Dressing](https://www.hongbaiweld.com/tag/256)󠁿 and Changing Systems Automatic electrode cap dressing and changing equipment designed to maintain consistent electrode geometry, reduce manual intervention, and support production continuity. ### 󠀁[Industrial Welding Automation](https://www.hongbaiweld.com/tag/354)󠁿 Customized welding platforms, robotic workstations, and integrated automation systems developed around specific production processes and customer requirements. This comprehensive product portfolio enables our partners to address a wider range of industrial welding applications. ## 3. Partnership Opportunities We are interested in establishing distribution and technical cooperation with companies that understand their local industrial markets and have the resources to develop long-term business relationships. We welcome inquiries from: **Industrial Welding Equipment Distributors** Companies specializing in welding machines, welding accessories, and industrial manufacturing equipment. **Automotive Equipment Suppliers** Suppliers serving automotive manufacturers, Tier 1 suppliers, and automotive component manufacturers. **Industrial Automation Integrators** Companies involved in robotic systems, automated production lines, welding workstations, and manufacturing process integration. **Industrial Equipment Service Providers** Companies with technical personnel and service capabilities for industrial equipment installation, commissioning, and maintenance. Potential partners are evaluated based on market coverage, relevant industry experience, technical capabilities, and business development plans. ![](https://www.hongbaiweld.com/wp-content/uploads/2026/11/2026110601352790.png) ## 4. Support for Our Distribution Partners A successful distribution relationship requires more than product supply. It depends on product knowledge, technical coordination, and the ability to respond effectively to local customer requirements. Hongbai provides support across four key areas. ### Product and Technical Support Product information, technical documentation, operating instructions, product training, and engineering guidance to help partners understand our equipment and communicate its technical value to customers. ### Sales and Marketing Support Product catalogs, technical presentations, product specifications, demonstration videos, and approved promotional materials to support local marketing and sales activities. ### Application and Project Support Technical assistance with product selection, application evaluation, equipment configuration, and customized solution discussions for specific customer projects. ### After-Sales Technical Support Technical coordination, remote troubleshooting, and engineering assistance to help partners address equipment-related questions and customer requirements. Support arrangements are determined according to product type and project scope. ## 5. Distributor Admission Requirements To establish a professional and sustainable distribution network, Hongbai evaluates prospective partners based on their business qualifications, industry experience, market resources, and technical capabilities. ### Business Qualifications and Market Resources Applicants must be legally registered businesses with legitimate business operations and relevant experience in industrial welding equipment, automotive manufacturing equipment, or industrial automation. Preferred partners should have: * An established local customer base and industry network. * Relevant experience in industrial equipment distribution or technical sales. * Sufficient commercial resources and local market influence. * The ability to develop customer relationships and promote Hongbai products. * Recognition of Hongbai’s products, business philosophy, and long-term development objectives. We value partners who demonstrate a genuine commitment to cooperation and confidence in the technical performance and market potential of our products. ### Technical Expertise and Service Capabilities Distributors should have qualified technical personnel with relevant welding knowledge and industrial equipment service experience. For Hongbai standard equipment, distributors are expected to provide basic technical assistance, including: * Equipment installation coordination and basic commissioning. * Routine maintenance. * Troubleshooting of common equipment issues. * Basic technical communication with local customers. For complex technical problems, Hongbai’s engineering team will provide appropriate technical assistance and remote support. For customized equipment and integrated automation projects, after-sales service responsibilities and support arrangements will be defined according to the specific project scope and contractual agreement. ## 6. Distributor Management and Cooperation Requirements ![ Key requirements for becoming an authorized Hongbai distributor, including business qualifications, market resources, technical expertise and after-sales service](https:// www.hongbaiweld.com/wp-content/uploads/2026/11/2026110601415369.png) To protect the interests of both parties and maintain an orderly distribution network, distributors are expected to comply with the following cooperation requirements. ### Project Registration and Protection Distributors are required to register qualified customer projects with Hongbai to establish project records and protect legitimate business opportunities. Each project submission should include: * End customer’s company name. * Project background and application requirements. * Equipment specifications or estimated product requirements. * Project status and expected purchasing schedule. * Relevant technical or commercial information. All submitted information must be accurate, complete, and verifiable. Hongbai will review project submissions and coordinate project registration and protection in accordance with the agreed distribution policy. Project protection is subject to confirmation by Hongbai. ### Sales Targets and Market Development Distributors are expected to establish a clear market development plan and actively promote Hongbai products within their authorized territories. Annual or periodic sales targets, market development objectives, and performance evaluation criteria may be established through mutual agreement, taking into account the distributor’s market conditions and business capabilities. Regular communication regarding sales performance, customer development, and market feedback is expected. ### Product Portfolio and Competition Policy Distributors shall comply with the product representation and competition provisions agreed upon by both parties. Any restrictions concerning the representation, manufacture, or sale of competing products within the authorized territory shall be subject to the specific terms of the signed distribution agreement. Distributors are expected to maintain professional representation of Hongbai products and avoid activities that may materially undermine the agreed commercial cooperation. ### Authorized Sales Territory Distributors are authorized to promote and sell Hongbai products within the geographical territory specified in the distribution agreement. Without prior written authorization from Hongbai, distributors shall not actively solicit customers, conduct targeted marketing, or establish distribution arrangements for Hongbai products outside their authorized territories. Cross-territory sales opportunities and customer inquiries should be communicated to Hongbai for coordination. The authorized territory, distribution scope, and related restrictions shall be determined by the signed distribution agreement. ### Business Conduct and Confidentiality Distributors are expected to comply with applicable local laws and regulations, maintain responsible business practices, protect confidential business and technical information, and uphold the reputation of Hongbai and its products. Both parties shall conduct business in accordance with the agreed distribution policies and contractual obligations. ## 7. Discuss a Distribution Partnership with Hongbai If your company operates in the industrial welding or automation sector and is interested in representing Hongbai in your market, we invite you to submit your company profile for consideration. To help us evaluate potential cooperation, please provide: * Company name and location. * Main business activities and product portfolio. * Target industries and customer groups. * Existing sales and technical service capabilities. * Relevant market experience and distribution coverage. * Your proposed market development plan. Our team will review your information and contact qualified applicants to discuss product suitability, local market requirements, and potential cooperation arrangements. **Hongbai | Intelligent Welding Equipment & Industrial Automation** For distribution inquiries, please contact our team through the partnership application form. ⌊👇⌉⌊👇⌉⌊👇⌉⌊👇⌉⌊👇⌉⌊👇⌉ [**[Explore Partnership Opportunities →]**](https://www.hongbaiweld.com/features-modular.html) ## Bringing the Production Line into the Classroom: Hongbai Technology’s Industry–Education Collaboration Featured by CCTV - Link: https://www.hongbaiweld.com/news4028.html - Published: 2026-11-02T11:34:00+08:00 - Author: zhouhui **A closer connection between industrial practice and technical education is helping prepare graduates for the demands of modern manufacturing.** [Hongbai Technology](https://www.hongbaiweld.com/tag/147)’s industry–education collaboration model was recently featured by China Central Television (CCTV), highlighting the company’s approach to developing skilled technical professionals through partnerships with higher education institutions. As manufacturers face growing demand for employees who can adapt quickly to production environments and take on technical responsibilities, Hongbai Technology is working with educational institutions to bring practical manufacturing experience into the classroom. Through company-sponsored training programs, students gain exposure to real production processes, technical requirements, and workplace standards before entering the workforce. ## Bringing Industrial Practice into Technical Education For many manufacturing companies, recruiting fresh graduates has traditionally involved a considerable period of onboarding, technical training, and workplace adjustment. Bridging the gap between academic knowledge and practical manufacturing experience remains an important challenge. ![Hongbai Technology's industry-education collaboration model featured by CCTV]( https://www.hongbaiweld.com/wp-content/uploads/2026/11/202611020207236.png) CCTV coverage of Hongbai Technology’s industry-education collaboration initiative, highlighting its approach to technical talent development for smart manufacturing. Hongbai Technology is addressing this challenge through its industry–education collaboration initiatives, including jointly developed training programs with educational institutions. Commenting on the approach in an interview with CCTV Finance, Hou Fuli, Deputy General Manager of Hongbai Technology, explained: _“In the past, newly recruited graduates required an extended period of pre-employment training. Now, graduates from our company-sponsored programs can take on meaningful responsibilities shortly after joining the company. They adapt quickly and can even handle specific tasks independently.”_ Through structured technical training during their studies, participating students have opportunities to gain practical experience in the company’s technical departments and production operations before graduation. Following successful assessments, they can transition into employment upon completing their studies. This approach reduces the adjustment period between education and employment while enabling the company to develop talent with a clearer understanding of actual production requirements. ## Preparing Technical Talent for the Changing Manufacturing Landscape As artificial intelligence (AI) becomes increasingly integrated into industrial applications, manufacturers face new challenges in translating emerging technologies into practical production solutions. This has created growing demand for professionals with both technical knowledge and the ability to implement technologies in real manufacturing environments. The scope of industry–education collaboration is also expanding. While earlier programs primarily focused on traditional engineering disciplines such as electrical automation and mechatronics, newer initiatives increasingly cover artificial intelligence, embodied intelligence, OpenHarmony, biopharmaceuticals, and industrial software. ![Technical training and practical manufacturing education through Hongbai Technology's industry-education collaboration program](https://www.hongbaiweld.com/wp-content/ uploads/2026/11/202611020209159.png) Practical technical training connects classroom education with industrial production requirements, helping students develop skills for manufacturing careers. These developments reflect a broader shift in manufacturing workforce requirements. Companies increasingly need professionals who can connect engineering fundamentals with practical application, equipment operation, and industrial technology deployment. For Hongbai Technology, integrating production experience, process requirements, and quality standards into technical education is an important part of addressing these needs. ## More Than Two Decades of Experience in Intelligent Manufacturing ![Hongbai Technology's manufacturing facility for intelligent welding equipment]( https://www.hongbaiweld.com/wp-content/uploads/2026/11/2026110202112935.jpg) The company’s talent development initiatives are supported by more than two decades of experience in the manufacturing industry. Established in 2003, Hongbai Technology is a National High-Tech Enterprise and a National-Level Specialized and Sophisticated “Little Giant” Enterprise. It is also an Executive Council Member of the China Welding Association. With a long-standing focus on automotive intelligent welding equipment, the company has remained committed to advancing China’s automotive equipment industry through independent research and development. Its independently developed stud welding systems have helped break the long-standing dominance of international brands in the domestic market, establishing a leading position in China’s stud welding equipment sector. Today, Hongbai Technology focuses on the development and manufacturing of intelligent equipment, as well as customized industrial software solutions. Its capabilities span core technology development, precision manufacturing, and system integration, providing a comprehensive foundation for industrial applications. The company employs nearly 600 people, with approximately 30% of its workforce dedicated to R&D. Annual R&D expenditure accounts for more than 15% of sales revenue. To date, Hongbai Technology has accumulated more than 200 patents and software copyrights in China and abroad. This combination of engineering expertise, manufacturing capabilities, and practical industrial experience provides a strong foundation for its collaboration with educational institutions. ## Developing Talent Alongside Technological Progress Technological advancement and talent development are closely connected. For intelligent manufacturing companies, investment in equipment and technological innovation must be accompanied by the development of professionals capable of applying these technologies in production environments. For Hongbai Technology, bringing the production line into the classroom is more than an alternative approach to recruitment. It is a way to introduce industrial standards, manufacturing processes, and quality awareness into the development of the next generation of engineers and technical professionals. By connecting technical education with actual manufacturing operations, the company aims to help graduates enter the workplace with a stronger understanding of industrial requirements and the practical skills needed to contribute. Hongbai Technology will continue to strengthen its partnerships with educational institutions, deepen industry–education collaboration, and explore more effective approaches to technical talent development. **By aligning education with industrial practice, Hongbai Technology is contributing to the development of skilled professionals and the long-term advancement of intelligent manufacturing.、** Learn more about our intelligent welding equipment, automotive welding solutions, and industrial automation capabilities. Visit our website: https://www.hongbaiweld.com/ ## Why Are Upper and Lower Electrode Caps Uneven After Dressing? Causes and Solutions - Link: https://www.hongbaiweld.com/news/interior-accessories4012.html - Published: 2026-10-29T16:32:44+08:00 - Author: zhouhui ![Upper and lower resistance spot welding electrode caps showing uneven projection after dressing.](https://www.hongbaiweld.com/wp-content/uploads/2026/10/2026102907461084. jpg) In automotive body-in-white (BIW) production, resistance spot welding electrodes are subjected to repeated pressure, heat, and material transfer. Regular electrode tip dressing is essential to restore the required weld face geometry and maintain consistent welding conditions. However, a common problem on production lines is that the upper and lower electrode caps have different protruding lengths after dressing. One electrode appears higher than the other, even though both electrodes have been processed by the same dressing unit. Why does this happen when the dressing unit is designed to dress both electrodes simultaneously? The key is to distinguish between **initial electrode length differences, unequal material removal, and electrode alignment errors**. Identifying the actual cause helps maintenance engineers correct the problem without unnecessary parameter changes or repeated production interruptions. Hongbai Technology provides electrode cap dressing equipment and AI vision inspection solutions for automotive welding applications, supporting more consistent electrode maintenance and quality inspection. ## 1. Understanding the Causes of Uneven Electrode Cap Projection During resistance spot welding, electrode caps gradually wear and their weld faces may become enlarged, deformed, or contaminated. Electrode tip dressing removes excess material and restores the required weld face geometry. In a properly configured dressing system, the upper and lower electrodes are processed according to the equipment’s design and the specified dressing parameters. However, **simultaneous dressing does not necessarily mean that both electrode caps will have identical final projection lengths**. The final result depends on three main factors: * **Initial projection:** The upper and lower electrode caps may already have different protruding lengths before dressing. * **Material removal:** The amount of material removed from each electrode may differ. * **Mechanical alignment:** Electrode misalignment or an incorrect dressing position may affect the cutting process and the resulting geometry. To investigate the problem, measure both electrodes before and after dressing. This helps determine whether the length difference existed before the dressing cycle or developed during the process. ![Rotary cutter dressing a resistance spot welding electrode cap to restore its face geometry.](https://www.hongbaiweld.com/wp-content/uploads/2026/10/202610290757194. png) Electrode cap dressing restores the working face geometry and helps maintain consistent welding conditions. ## 2. Five Common Causes of Uneven Electrode Cap Lengths ### 2.1 Incorrect Electrode Cap Installation or Different Initial Dimensions The first step is to verify the condition of the electrodes before dressing. Different electrode cap dimensions, inconsistent seating depth, or incorrect installation can create a projection difference before the dressing cycle begins. Differences in electrode holder position or welding gun geometry may also contribute. **Recommended checks:** * Verify that the upper and lower electrode caps have the correct specifications. * Check that both caps are fully seated and securely installed. * Measure the initial electrode cap projection using the same reference point. * Compare the measurements before and after dressing. If the difference is already present before dressing, investigate the installation and electrode assembly rather than simply increasing dressing time. ### 2.2 Worn or Damaged Dressing Cutters The dressing cutter directly affects the resulting weld face geometry. Worn cutting edges, damaged blades, loose fasteners, or an incorrectly matched cutter can cause uneven cutting, incomplete dressing, or irregular electrode faces. Cutter compatibility is particularly important when the upper and lower electrodes have different geometries. A standard cutter assembly designed for matching electrode caps may not be suitable for every special configuration. Hongbai’s electrode cap dressing solutions can be configured with different cutter options according to the applicable electrode geometry and process requirements. **Recommended checks:** * Inspect the cutter edges for wear, chipping, and damage. * Verify compatibility between the cutter and electrode cap geometry. * Check the cutter mounting and fastening. * Inspect the dressed faces for eccentricity, uneven cutting, or incomplete dressing. Cutter wear should not automatically be identified as the cause of a projection difference. Measurements and face inspection are needed to confirm the diagnosis. ### 2.3 Electrode Misalignment and Incorrect Dressing Position Electrode alignment is critical to consistent tip dressing. If the electrode axis is offset from the cutter’s rotational center, the cutting conditions may become uneven. This can result in an off-center weld face, incomplete material removal, or irregular face geometry. A tilted electrode holder, incorrect welding gun position, or a displaced dressing unit may also affect dressing quality. **Recommended checks:** * Verify the electrode position relative to the dressing cutter. * Check the alignment of the upper and lower electrode axes. * Inspect the electrode holders for bending or excessive tilt. * Confirm that the dressing unit is correctly positioned and securely mounted. If the problem occurs on only a few robots, begin with the individual welding gun, electrode holders, and dressing station before changing parameters across the entire production line. ### 2.4 Malfunctioning Floating Mechanism or Unstable Drive Conditions Some electrode dressing units incorporate a floating mechanism to accommodate changes in electrode position and maintain suitable contact with the cutter. If the floating mechanism sticks, the pneumatic supply becomes unstable, or the drive system operates incorrectly, the contact conditions during dressing may change. The inspection procedure depends on the equipment design. Pneumatic systems require checks of air pressure, cylinders, and floating mechanisms, while servo-driven systems require checks of drive status, positioning, and mechanical transmission. **Recommended checks:** * Inspect the floating mechanism for restricted movement. * Verify air pressure and pneumatic stability where applicable. * Check bearings, transmission components, and drive operation. * Confirm that the dressing pressure and cycle settings meet the equipment specifications. The objective is to identify the actual mechanical or control fault rather than assume that every projection difference is caused by insufficient dressing pressure. ### 2.5 Incorrect Dressing Parameters or Different Electrode Wear Conditions Dressing time and material removal settings influence how much material is removed during each cycle. Insufficient dressing may leave worn areas or contamination on the weld face. Excessive material removal, on the other hand, can shorten electrode service life. The upper and lower electrodes may also enter the dressing cycle with different wear conditions, mushrooming, deformation, or copper pickup. These differences can affect the final result. **Recommended checks:** * Verify dressing time and material removal settings. * Compare the initial wear conditions of the upper and lower electrodes. * Inspect for copper pickup, surface irregularities, and incomplete dressing. * Adjust one parameter at a time within the approved operating range and record the results. The objective is not simply to make both electrodes look the same length. It is to restore the required weld face geometry while controlling electrode consumption. ![Illustration of dressing cutter wear and electrode misalignment as possible causes of uneven electrode cap dressing.](https://www.hongbaiweld.com/wp-content/uploads/ 2026/10/2026102907592858.jpg) Cutter wear, electrode misalignment, and inconsistent dressing conditions should be checked when cap projections differ. ## 3. How Can Uneven Electrode Caps Affect Spot Welding Quality? The effect of an electrode projection difference depends on the welding gun design, workpiece geometry, actual dimensional deviation, and the compensation available in the system. When the difference exceeds the applicable process tolerance, potential consequences include: **Uneven electrode contact** One electrode may contact the workpiece earlier than the other, depending on the welding gun configuration and workpiece position. **Changes in the effective electrode force distribution** If the projection difference affects the contact condition or welding gun geometry, the actual force distribution may differ from the intended condition. **Inconsistent weld quality** Electrode face diameter, face geometry, alignment, and contact conditions influence resistance spot welding. If the projection difference is accompanied by electrode misalignment or irregular weld faces, process consistency may be affected. **Additional maintenance and downtime** If the electrode geometry falls outside the limits monitored by the welding system, additional inspections, alarms, or maintenance interventions may be required. For automotive body-in-white production, maintaining consistent electrode geometry is an important part of welding process control. Acceptable limits should be established according to the welding gun design, equipment specifications, and validated process requirements. ## 4. A Practical Troubleshooting Procedure Instead of repeatedly changing dressing parameters, maintenance teams can follow a structured inspection sequence. | Step | Inspection | Objective | | 1 | Measure upper and lower electrode projection before and after dressing | Identify when the difference develops | | 2 | Verify electrode cap dimensions and installation | Eliminate initial dimensional differences | | 3 | Inspect dressing cutters and mounting | Identify cutting-related problems | | 4 | Check electrode alignment and dressing position | Detect mechanical positioning errors | | 5 | Inspect the floating mechanism and drive system | Identify unstable movement or contact conditions | | 6 | Review dressing parameters | Confirm appropriate process settings | | 7 | Re-measure electrode geometry and validate weld quality | Verify the effectiveness of corrective action | This procedure helps distinguish installation problems from dressing-related faults and reduces unnecessary trial-and-error adjustments. ## 5. How Hongbai Supports Electrode Dressing Quality Control For automotive manufacturers, correcting a dressing defect is only part of the challenge. Maintaining repeatable dressing quality and identifying recurring defects are equally important. Hongbai Technology develops electrode cap dressing equipment and AI vision inspection solutions for automotive welding applications. Depending on the selected configuration, dressing and inspection can be integrated into an electrode maintenance workflow. ### 󠀁[AI Vision Inspection](https://www.hongbaiweld.com/tag/227)󠁿 for Electrode Face Defects Hongbai’s AI vision inspection solution is designed to identify 11 types of electrode cap face defects, helping operators detect conditions that may be difficult to assess consistently through manual visual inspection. The inspection categories include: * Black marks * Protrusions * Copper pickup * Pits * Radial marks * Excessive face size * Insufficient face size * Irregular face geometry * Eccentric electrode faces * Flower-pattern marks * Incomplete dressing * Uneven dressing These defect categories help production teams identify problems with electrode face condition and dressing quality. ### Dual-Criteria NG Judgment Hongbai’s AI inspection solution uses a dual-criteria judgment method based on the total NG defect area and the NG area ratio. According to the configured inspection logic, both criteria are evaluated against their respective thresholds. This helps distinguish acceptable surface variations from defects that meet the configured NG conditions. ### Inspection Statistics and Traceability The system supports OK/NG statistics and inspection records, helping production teams review defect trends and investigate recurring dressing problems. For automotive production lines operating multiple robotic welding guns, these records can provide useful information for maintenance planning and quality analysis. It is important to distinguish between **electrode face defect inspection and dimensional measurement**. Detecting an irregular weld face does not automatically provide a direct measurement of the overall projection difference between the upper and lower electrodes. If an application requires measurement of electrode cap projection, axis offset, or angular deviation, the relevant geometric measurement functions and their validated accuracy must be confirmed for the selected system configuration. By combining appropriate dressing equipment, routine mechanical inspections, and suitable vision inspection methods, manufacturers can establish a more controlled and traceable electrode maintenance process. ## Correct the Root Cause, Not Just the Symptom Uneven electrode cap projection after dressing can result from incorrect installation, worn or mismatched cutters, electrode misalignment, mechanical instability, or unsuitable dressing parameters. The most effective approach is to measure both electrodes before and after dressing, identify when the difference develops, and correct the corresponding cause. For automotive manufacturers seeking more consistent electrode maintenance, Hongbai’s electrode cap dressing and AI vision inspection solutions offer options for improving dressing quality control and defect traceability. **Consistent electrode geometry starts with the right dressing process—and continues with reliable inspection.** Hongbai Technology ## Servo vs. pneumatic spot welding guns: how they differ and how to choose - Link: https://www.hongbaiweld.com/news/interior-accessories3975.html - Published: 2026-10-24T11:37:16+08:00 - Author: zhouhui _With a Focus on Hongbai Technology’s Servo Welding Gun Technology Based on [Hollow Electric Cylinder](https://www.hongbaiweld.com/tag/332) s_ ## Abstract Resistance spot welding is a core process in automotive body-in-white (BIW) manufacturing. The welding gun connects mechanical motion with the welding process, making force consistency and electrode movement critical to weld quality and production stability. Two common actuation approaches are pneumatic and electric servo. Pneumatic guns use compressed air to drive a cylinder and are well established, often with a lower initial investment. Servo-driven guns use a servo motor and electric cylinder to program electrode position, movement speed, and the force application sequence. The right choice depends on the material, process requirements, level of control, and integration with the wider production system. This article compares both technologies in terms of force control, process adaptability, and robot integration, with a focus on Hongbai Technology’s hollow electric cylinders for robotic spot welding in electric vehicle manufacturing. Applications include aluminum alloy, high-strength steel, and multi-sheet welding. ![Robotic spot welding gun used in automotive body-in-white assembly](https://www. hongbaiweld.com/wp-content/uploads/2026/10/2026102402480218.png) Pneumatic and servo-driven spot welding guns for automated automotive body assembly. ## 1. Force Consistency: The Numbers Behind the Process Force consistency is best evaluated against actual welding parameters. Hongbai’s SHF inverter DC spot welding system lists representative process parameters for steel applications, including: * **Electrode force:** 80–150 kgf * **Welding current:** 2.1–2.8 kA * **Weld time:** 5–8 cycles Aluminum welding can require a substantially different process window. One published application uses the following parameters: | Parameter | Aluminum welding case | | Sheet stack | 2+2 mm | | Electrode force | 6,000 N | | Welding current | 37,000 A | | Weld time | 180 ms | These figures describe a specific application, not universal settings for every material or joint. The practical question is whether the gun can maintain the required process conditions from the first weld to the four-thousandth weld of a production shift. Repeatability over time matters just as much as achieving a target value during initial setup. ## 2. 󠀁[Pneumatic Spot Welding](https://www.hongbaiweld.com/tag/329)󠁿 Guns: A Proven Solution Pneumatic guns generate electrode force through a pressure balance. Compressed air drives the cylinder, and the resulting force acts against the resistance of the workpiece and the mechanical system. ### How the system works A pneumatic gun can be a practical choice when the material, sheet thickness, and process window are relatively stable. Its established design and generally lower initial investment make it attractive for conventional steel applications. Hongbai Technology’s SHF inverter DC spot welding system uses a proportional-valve- controlled pneumatic servo mechanism. It supports adaptive control of welding force and welding current, allowing one gun to accommodate two or more different processes at a single station. For larger gun configurations, the gun body is machined from high-grade aviation aluminum to reduce weight while maintaining rigidity and strength. ### What affects force consistency? Pneumatic force is influenced by more than the programmed welding recipe. Relevant factors include: * Source pressure and fluctuations in the plant air supply * Pressure drop across long or shared air lines * Seal friction and cylinder condition * Ambient temperature and maintenance status The cylinder’s stroke end is generally determined by a mechanical limit or the system’s pressure balance. Unlike a servo system, a conventional pneumatic arrangement does not inherently provide freely programmable electrode positioning or continuous position feedback. Proportional valves and additional sensors can improve pneumatic control. The actual capability therefore depends on the specific gun and control configuration, rather than on the pneumatic principle alone. ## 3. 󠀁[Servo Spot Welding](https://www.hongbaiweld.com/tag/328)󠁿 Guns: Programmable Motion and Force Control Servo-driven guns use a servo motor and electric cylinder to control electrode movement. For more details, see our [hollow servo electric cylinder for spot welding](https://www.hongbaiweld.com/news/interior-accessories3763.html). Depending on the system configuration, electrode position and motion can be programmed, while force can be monitored or controlled through an appropriate feedback arrangement. The practical advantage is the ability to coordinate gun movement with the requirements of different materials, sheet stacks, and production recipes. ### Hongbai’s robot SHF spot welding system Hongbai Technology’s **robot SHF inverter DC spot welding system** uses an electric servo gun with real-time adaptive control of welding force and current. **Note on product designations:** Hongbai’s SHF inverter DC spot welding systems are offered in both a non-robot configuration, using a proportional-valve-controlled pneumatic servo gun, and a robot configuration, using an electric servo gun. The pneumatic mechanism described in Section 2 applies to the non-robot configuration; the electric servo gun described here applies to the robot system. The system is designed for applications involving: * Plain steel * Zinc-coated steel * Hot-formed steel * High-strength steel * Aluminum alloy Hongbai specifies low-spatter performance, including essentially spatter-free results under designated conditions for multi-layer zinc-coated steel and high-strength steel. Actual results depend on the material combination, electrode condition, welding parameters, and validated process window. ### Digital control with the robot MF system The robot MF inverter DC spot welding system uses a fully digital power supply with a high-speed DSP. Its control system incorporates adaptive functions designed to accommodate different sheet thicknesses and welding conditions. Depending on the configured process, a single gun at one station can handle cold- rolled, galvanized, hot-formed, and high-strength steel. ### Servo gun configuration for aluminum For aluminum welding, the gun features a modular body designed for compatibility with multiple robot brands and quick changeover. The configuration supports single or dual welding transformers. Key features include: * Electric servo drive * Gun-arm force capability specified at **900 kgf and above** * Real-time force monitoring and control * Programmable weld time and welding current * Parameter adjustment through a handheld programmer Precise control of welding current and electrode force helps improve weld strength and consistency. The actual performance must be validated against the specific aluminum alloy, sheet stack, electrode geometry, and welding schedule. ## 4. Process Adaptability by Material Different materials place different demands on the welding process. Actuator selection should follow the material and joint requirements, rather than the other way around. ### Galvanized and multi-layer zinc-coated steel Zinc melts and vaporizes during resistance spot welding, affecting contact conditions and potentially contributing to spatter. The electrodes must establish appropriate contact and force before and during current application. For multi-layer zinc-coated steel, force control and electrode movement can help stabilize the process. Hongbai specifies essentially spatter-free performance for designated applications using its servo gun. Such claims should be evaluated against the actual production conditions and acceptance criteria. ### Aluminum alloy Aluminum places demanding requirements on welding current, electrode force, and process timing. One published application uses: | Parameter | Value | | Sheet stack | 2+2 mm | | Electrode force | 6,000 N | | Welding current | 37,000 A | | Weld time | 180 ms | | Gun-arm force capability | 900 kgf and above | | Maximum controller welding current | Up to 60,000 A | The controller’s inverter output is specified at 1.8 kA. This value should not be confused with the welding current delivered at the electrodes, which depends on the transformer and system configuration. For this type of application, maintaining the required force and current throughout the weld cycle is essential. Changes in electrode force cannot always be compensated for simply by adjusting the current recipe. ### High-strength and hot-formed steel High-strength and hot-formed steels can be challenging because of their mechanical properties and the requirements of the joint. A material with a yield strength of 1,560 MPa, for example, can require careful control of electrode contact and force throughout the welding cycle. Hongbai’s 10 kHz SHF gun is specified for low-spatter welding of high-strength steel under designated conditions. One published application combines: * **Outer sheet:** 2.0 mm, 1,560 MPa hot-formed steel * **Middle sheet:** 3.0 mm, 700 MPa steel * **Other sheet:** 2.0 mm, 700 MPa steel This illustrates why material combinations and stack geometry need to be considered when choosing a welding gun. The appropriate force profile and welding schedule must be validated for the actual joint. ### What these materials have in common All three applications require controlled electrode contact, force, and current. The degree of control required, however, varies by material. A stable pneumatic system may be sufficient for a conventional steel application. Aluminum or demanding multi-sheet combinations may place greater emphasis on programmable motion, force monitoring, and repeatable process control. ![Robotic spot welding of automotive body panels and high-strength steel structures]( https://www.hongbaiweld.com/wp-content/uploads/2026/10/2026102402460582.jpg) Material properties and sheet-stack configurations influence spot welding requirements. ## 5. Shop-Floor Considerations: Beyond the Datasheet The differences between pneumatic and servo guns become clearer during daily production. Changeovers, electrode maintenance, and supply fluctuations can all affect how consistently a process runs. ### Gun changeover **Servo gun:** Position and motion sequences can be stored in the program and recalled with the welding recipe. The system can then establish the required electrode position and force-control conditions. **Pneumatic gun:** After a gun change, the regulator settings and delivered force may need to be checked again. Results depend on the cylinder, seal condition, and air-line pressure. Hongbai’s robot servo gun is designed for quick changeover across multiple robot brands, supporting production environments where equipment configuration changes regularly. ### Electrode replacement and redressing Electrode caps wear during production, and dressing changes their geometry and length. These changes can affect electrode contact and the relationship between gun position and the workpiece. A servo gun can use programmable position control to compensate for changes in electrode length, provided the control strategy and calibration support that function. A conventional pneumatic gun generally has a fixed stroke endpoint, so compensation may require mechanical adjustment or changes to the setup. Hongbai also supplies [electrode-cap dressers and combination dresser-changer units](https://www.hongbaiweld.com/all-product/robot-series/daytime-running-lights685.html), including automated units for robot guns. Together, these products support electrode maintenance as part of the overall welding process. ### Air-pressure fluctuations Air-pressure variation is an important consideration for pneumatic systems. Source pressure, line pressure drop, seal friction, and temperature can influence the force delivered by the cylinder. An electric servo gun removes compressed air as the primary actuator, but its force performance still depends on the mechanical design, drive configuration, feedback arrangement, and calibration. Where force consistency is critical, measurement is preferable to relying solely on the programmed setpoint. ### Force verification and traceability Hongbai’s gun force inspection unit supports: * Upper and lower force deviation limits * In-line and out-of-line alarms * Peak-value hold * Test reports and curves saved through a PC * Traceability of force inspection results This allows delivered force to be checked against defined acceptance limits. It also helps distinguish between a programmed target and the force actually measured during verification. For production teams, that distinction matters: process settings define what the system is intended to do, while inspection data helps establish whether the equipment meets the required conditions. ![Comparison of pneumatic cylinder and electric servo actuator systems for spot welding guns](https://www.hongbaiweld.com/wp-content/uploads/2026/10/2026102402281416. jpg) Comparing pneumatic and electric servo actuation principles for spot welding guns. ## 6. How to Choose: Servo or Pneumatic? The right choice depends on the material, required control functions, production conditions, and total cost of ownership. ### When to specify a servo gun A servo gun deserves serious consideration when one or more of the following conditions apply: **Aluminum is part of the sheet stack.** The published 2+2 mm aluminum application uses 6,000 N force and 37,000 A current, with gun-arm force capability above 900 kgf and real-time force monitoring. These requirements make force control and validation especially important. **Force must be monitored or traced.** Where the production process requires force verification, documented inspection limits, and saved test curves, a suitable servo system combined with a force inspection unit can support the required control and traceability workflow. **Electrode position must be programmable.** Stations handling different sheet thicknesses or material combinations may benefit from programmable positioning and recipe-based motion control. **The air supply is unstable.** Long air lines, shared supply branches, or significant pressure fluctuations can complicate the control of pneumatic guns. **Changeovers are frequent.** Quick-change mounting and recipe-based setup can help simplify the transition between different production configurations. **The material stack is demanding.** High-strength steel, hot-formed steel, and multi-layer galvanized assemblies may require tighter control of electrode movement and force. The final choice should be based on validated welding results rather than actuator type alone. ### When pneumatic remains the better buy Pneumatic guns remain attractive in applications where their capabilities already meet the production requirements. | Production condition | Why pneumatic may be suitable | | Conventional cold-rolled or galvanized steel | A stable material and thickness range may not require programmable servo positioning | | Stable air supply | Pressure-related variation can be managed within the validated process window | | No per-weld force traceability requirement | Additional monitoring capability may not justify its cost | | Wide process window | The simpler configuration may provide adequate performance | | Tight capital budget | Lower initial investment can make pneumatic systems more economical | Hongbai’s SHF pneumatic-servo configuration also offers adaptive control of welding force and current. Where those functions are sufficient, upgrading to a fully electric servo actuator may not deliver enough additional value to justify the investment. ### Understanding the cost boundary There is no universal price threshold at which servo becomes more economical than pneumatic. The crossover depends on three main cost categories: 1. **Equipment investment:** The actuator, gun structure, controller, and welding transformer. 2. **Operating costs:** Maintenance, consumables, setup time, and changeover requirements. 3. **Quality costs:** Scrap, rework, downtime, and the cost of failing to meet process requirements. For aluminum applications using 6,000 N force and 37,000 A current, the required process capability may justify the additional investment in a servo system. For conventional cold-rolled steel operating within the parameter range listed for this equipment (around 80–150 kgf and 2.1–2.8 kA), a pneumatic gun may be the more economical choice if it consistently meets the validated process requirements Hongbai’s available product information does not provide comparable unit prices or verified ROI figures for both actuator types. A meaningful cost comparison should therefore use actual line data, including scrap rates, rework costs, equipment pricing, and maintenance expenses. ## 7. Hongbai Technology: From Actuator Development to Production Integration The difference between an actuator component and a production-ready welding solution lies in how the mechanical, electrical, and control systems work together. Hongbai Technology’s approach combines hollow electric cylinder development, robot- gun integration, welding power control, and force verification. ### 7.1 Developing the hollow electric cylinder Hongbai’s product portfolio includes hollow electric cylinders alongside robot spot welding systems, stud welding systems, spot welding equipment, and electrode dressing solutions. The servo mechanism for a robotic spot welding gun can use a hollow electric cylinder developed specifically for this application. It can also work with mainstream third- party servo drives, avoiding dependence on a single drive ecosystem. Two structural configurations are available: * **Linear electric cylinder:** For installations suited to a straight-line arrangement. * **Retractable or fold-back electric cylinder:** For applications where axial length and mounting space are more constrained. This flexibility helps adapt the actuator layout to the robot and station design. ![Hongbai hollow servo electric cylinder integrated with a robotic spot welding gun](https://www.hongbaiweld.com/wp-content/uploads/2026/10/2026102402401451.jpg) Hongbai Technology’s hollow electric cylinder is designed for integration into robotic spot welding guns. ### 7.2 Integrating the gun and transformer A robot wrist must carry the mass of the gun and its associated components. Reducing this load is an important consideration in system integration. Hongbai has developed compact transformer configurations intended to integrate the transformer and gun into a single assembly, helping reduce the load imposed on the robot. For aluminum welding applications, the company offers a coordinated solution combining a 1 kHz or 2 kHz welding transformer with a hollow electric cylinder for new energy vehicle welding equipment. ### 7.3 Designing the gun body for rigidity Programmable motion alone cannot guarantee accurate electrode movement if the gun structure deflects under load. Hongbai’s robot gun bodies are machined from aviation aluminum and high-grade copper to combine structural rigidity, strength, low deformation, and electrical conductivity. The body design also incorporates multiple appearance patents. Both C-type and X-type guns are available for integration with a range of domestic and international industrial robots, subject to the specific mounting and interface requirements. ### 7.4 Matching the control system to the application The robot SHF spot welding system uses inverter technology, full-bridge soft switching, and closed-loop welding-current control. Its 10 kHz welding transformer is designed for compact size and high efficiency. The MF controller, intended for applications including aluminum welding, has a specified inverter output of 1.8 kA at a 20% duty cycle. It supports transformers from multiple manufacturers and a maximum welding current of up to 60,000 A. Communication options include Profinet, Profibus, and EtherNet-based interfaces, with configuration determined by customer and system requirements. ### 7.5 Production applications Hongbai’s SHF spot welding systems and hollow-electric-cylinder servo guns have been used in projects associated with: * FAW-Volkswagen: Jetta, Bora, Qingdao, and Sagitar spare-parts projects * SAIC-Volkswagen: Tiguan longitudinal-beam, A-Plus, and Yeti projects * Dongfeng Peugeot-Citroën: G25/G95 retrofit projects * FAW-Haima, Dongfeng Passenger Vehicle, and BYD programs These applications involve high-strength steel, multi-layer steel, and aluminum welding. The robot servo gun has also been used on an SAIC-Volkswagen B+SUV main welding line and a GM D2UX platform line. The published 2+2 mm aluminum application, using 6,000 N force, 37,000 A current, and 180 ms weld time, is associated with new energy vehicle body aluminum welding. Individual project configurations and material combinations should be confirmed against the relevant application records when citing a specific installation. ### 7.6 Verifying force on the production floor The gun force inspection unit completes the control and verification workflow. It supports upper and lower deviation limits, in-line and out-of-line alarms, peak- value hold, and PC-based storage of test reports and curves. The result is a more structured way to verify whether delivered force meets the required limits, rather than relying only on the actuator’s programmed settings. For a production system using a hollow electric cylinder, this verification capability helps connect the intended force-control strategy with measurable results on the shop floor. ## 8. Choose the Actuation System Around the Process Pneumatic and servo spot welding guns serve different production needs. Pneumatic guns establish electrode force through air pressure and can be highly cost-effective when the supply is stable and the process window is well established. Servo guns offer programmable electrode movement and can support more advanced force monitoring and control, depending on their configuration. **Material requirements should come first.** Aluminum welding may demand high force and current, while high-strength steel and multi-layer galvanized assemblies place particular emphasis on stable electrode contact and process control. The appropriate welding schedule must always be validated for the actual material stack and joint. **Production conditions matter just as much.** Gun changeovers, electrode replacement, dressing, and air-pressure variation all influence daily process stability. Programmable positioning, recipe-based control, and force verification can help address these challenges where they are needed. Consider a servo gun when the process requires programmable positioning, demanding material combinations, more advanced force control, or documented force verification. A pneumatic gun may remain the better investment for conventional steel applications with stable air supply, limited changeovers, and no requirement for per-weld force traceability. Hongbai Technology’s approach focuses on the complete system: developing hollow electric cylinders for robotic spot welding, supporting third-party servo drives, offering linear and fold-back configurations, integrating compact transformers, and matching gun mechanics with welding controllers. Its product portfolio also includes electrode dressing equipment and a force inspection unit to support maintenance and verification. The objective is not simply to achieve a target setting. It is to establish a welding process that can be controlled, checked, and maintained throughout production. ### Discuss Your 󠀁[Robotic Spot Welding](https://www.hongbaiweld.com/tag/289)󠁿 Application Selecting a welding gun starts with the material stack, required electrode force, cycle time, and robot integration constraints. These factors help determine whether a pneumatic or servo-driven solution is appropriate for your production line. If you are evaluating a robotic spot welding system, share your material combination and application requirements with our team. [Contact Hongbai Technology](https://www.hongbaiweld.com/contact.html) [Linkedin](https://www.linkedin.com/company/hongbaiweld/?viewAsMember=true) ## Three-Loop Control in Linear Servo Stud Welding Guns - Link: https://www.hongbaiweld.com/news/interior-accessories3957.html - Published: 2026-10-20T15:10:33+08:00 - Author: zhouhui **How position, velocity, and current control work together to achieve precise, repeatable gun motion.** In automated [stud welding](https://www.hongbaiweld.com/tag/145), the welding gun must reach programmed positions, follow a defined motion profile, and respond quickly to changes in mechanical load. These requirements are managed by a cascaded three- loop servo control architecture: the position loop, velocity loop, and current loop. Hongbai’s servo control architecture combines MCU and FPGA processing to coordinate motion commands, feedback regulation, and gun movement throughout the welding cycle. ## 1. The Three Loops of 󠀁[Servo Control](https://www.hongbaiweld.com/tag/325)󠁿 ### Position Loop: Accurate Positioning The outermost loop controls the position of the gun’s lifting mechanism using feedback from a high-resolution optical linear encoder. Its main functions are to track commanded positions, reduce positioning errors, and maintain the required position during designated stages of the welding cycle. Accurate positioning helps ensure that the gun follows the programmed movement sequence and establishes the intended lift conditions for the welding process. ![Block diagram of position, velocity, and current loops in a linear servo stud welding gun.](https://www.hongbaiweld.com/wp-content/uploads/2026/10/2026102006035722. png) The position, velocity, and current loops work together to regulate positioning accuracy, motion tracking, and motor torque response. ### **Velocity Loop: Motion Profile Tracking** The velocity loop regulates motor speed according to the trajectory generated by the motion planner. Velocity feedback, derived from position measurements or dedicated estimation, enables the controller to correct tracking errors. The specified motion configuration includes: * **Maximum velocity:** adjustable range of approximately 50–800 mm/s (recommended 400 mm/s) * **Acceleration:** adjustable range of approximately 20–80 m/s² (recommended 50 m/s²) These are application-specific settings. Actual motion performance depends on the gun mechanism, moving mass, stroke, and load conditions. ### Current Loop: Fast Torque Response The innermost loop regulates servo motor phase current, which is closely related to motor torque. It enables the drive to respond to acceleration commands and changes in mechanical load. The specified servo-drive parameters are: | Parameter | Value | | Current-loop control period | 20 μs | | Switching frequency | 50 kHz | | Maximum current command/output | ±20 A | | Specified current response | 10 A within 40 μs | These figures apply to the specified drive configuration and should be verified against its technical documentation. **Servo motor current is different from welding current.** Motor current controls the gun’s movement; welding current supplies the energy required to form the weld. The two systems must be coordinated but perform different functions. ## 2. MCU + FPGA Control Architecture The three loops have different processing requirements. Hongbai’s specified architecture distributes them between an MCU and an FPGA. | Control function | Hardware | Control period | | Position loop | MCU | 50 μs | | Velocity loop | MCU | 50 μs | | Current loop | FPGA | 20 μs | | Motor power-stage switching | FPGA-based control and IPM | 50 kHz | The MCU executes position and velocity regulation in synchronization with the welding controller. The FPGA handles the faster current loop, enabling a shorter current- control interval. This division supports coordinated motion control while allowing the motor-current regulation stage to respond more rapidly to torque demands. ## 3. Motion Planning and Feedback The motion planner uses T-profile motion planning and interpolation at a specified 50 μs interval. It generates three reference signals: * **Position command:** Defines the target position. * **Velocity command:** Defines the desired movement speed. * **Acceleration feedforward:** Helps anticipate the torque demand associated with planned acceleration. The servo controller monitors position, velocity, and motor-current feedback to regulate actual movement against these commands. This combination of trajectory planning and closed-loop feedback helps the gun follow the intended motion profile while responding to real operating conditions. ## 4. Four Stages of Gun Motion ![Position, velocity, and acceleration profiles illustrating the programmed movement of a linear servo stud welding gun.](https://www.hongbaiweld.com/wp-content/uploads/ 2026/10/2026102006352964.jpg) The programmed motion profile defines the gun’s movement between target positions and the timing of each holding stage. The specified motion sequence consists of four stages: 1. **Pos0 to Pos1:** The gun moves to the first programmed position using a T-profile, with a specified acceleration of approximately 30 m/s². 2. **Hold at Pos1:** The controller maintains the commanded position. 3. **Pos1 to Pos3:** The gun follows the next motion profile, with acceleration of approximately 50 m/s² (about 5.1 g) and a maximum velocity of 400 mm/s. 4. **Hold at Pos3:** The gun maintains its commanded position for the required stage of the welding sequence. Throughout these stages, the servo controller regulates gun motion while the welding controller coordinates the relevant welding events. The exact timing depends on the configured welding process. ## 5. Waveform Monitoring and Fault Diagnosis Recorded servo signals help engineers evaluate tracking performance, investigate abnormal movement, and troubleshoot the gun mechanism. Hongbai’s specified HEAS configuration includes waveform recording for position error, velocity tracking, motor current, and current error. | Monitored signal | Potential indication | | Position error | Incorrect tuning, excessive load, or mechanical resistance | | Velocity tracking | Motion-profile mismatch or abnormal mechanical load | | Motor current | Increased friction or restricted gun movement | | Current error | Servo tracking issues, mechanical resistance, or potential drive-related faults | The specified configuration includes example diagnostic thresholds of: * Motor current ≥15 A sustained for approximately 5 ms. * Current error ≥2 A sustained for approximately 5 ms. These are configuration-specific thresholds, not universal fault limits. A single signal cannot conclusively identify a fault; engineers should correlate recorded data with the commanded motion, operating stage, and mechanical condition. Waveform analysis can support commissioning, parameter tuning, and maintenance by showing how the gun responds under actual operating conditions. ## Engineering Considerations for Automated Welding Servo performance depends on more than encoder resolution or motor response. Motor sizing, motion-profile tuning, mechanical resistance, gun alignment, and welding- cycle timing all affect the final result. For automated production, the objective is to achieve repeatable gun motion and reliable coordination with the welding process. Weld quality must still be validated against the application-specific materials, welding parameters, and process requirements. At Hongbai Technology, servo control is part of the engineering behind our automated stud welding solutions. We develop stud welding equipment and integrated welding systems for automotive manufacturing and other industrial applications, with a focus on precise motion control, process consistency, and reliable production performance. ![Hongbai automated stud welding equipment and robotic welding workstation for automotive manufacturing.](https://www.hongbaiweld.com/wp-content/uploads/2026/10/2026102006420467. jpg) Automated stud welding solutions for automotive and industrial manufacturing. ## Looking for a Stud Welding Solution? Hongbai Technology provides stud welding equipment and automated welding solutions for automotive and industrial applications. **Contact Hongbai to discuss your stud welding requirements and automation projects.** [Linkedin](https://www.linkedin.com/company/hongbaiweld/?viewAsMember=true) ## Stud Welding Process Parameters Explained: Pilot Current, Welding Current, and Upset Time - Link: https://www.hongbaiweld.com/news/interior-accessories3929.html - Published: 2026-10-16T14:05:52+08:00 - Author: zhouhui _Hongbai Technology Technical Column | Professional Series_ ## Introduction In [stud welding](https://www.hongbaiweld.com/tag/145), a small change in current or welding time can make a noticeable difference to the final weld. Too little energy may result in incomplete fusion, while excessive heat can cause spatter, an irregular weld collar, or burn-through on thin sheet metal. On Hongbai Technology’s SAW-3600 series stud welding system, parameters such as pilot current, welding current, and upset time are used to configure the welding cycle. Getting the best result is not simply a matter of increasing the current. The stud, base material, surface condition, lift height, and welding gun movement all need to be considered together. This article looks at how these parameters work, the reference settings available on the equipment, and what to consider when adjusting them for different applications. ## 1. How the Stud Welding Cycle Works In the servo-controlled welding process described here, the electrical output and the mechanical movement of the stud work together through four stages. ![Four-stage short-cycle arc stud welding illustration showing contact, pilot arc, main welding arc and plunge](https://www.hongbaiweld.com/wp-content/uploads/2026/ 10/2026101605203630.jpg) The welding cycle progresses from initial contact to arc initiation, main welding and plunge. **Stage 1: Initial contact** The stud is positioned against the workpiece, creating the electrical contact required to initiate the welding sequence. Consistent positioning and stable contact help establish repeatable starting conditions. **Stage 2: Pilot arc** The power source applies the pilot current while the servo welding gun lifts the stud away from the workpiece. This establishes the pilot arc before the main welding stage begins. The pilot stage helps initiate the arc and prepare for the main welding cycle. On coated or contaminated surfaces, the results also depend on the coating, surface cleanliness, and the selected current and time. **Stage 3: Main welding arc** When the stud reaches the preset lift height, the power source delivers the main welding current for the programmed duration. The arc melts the end of the stud and the corresponding area of the base material, forming a molten pool. The servo gun then drives the stud toward the workpiece and into the molten pool. The relationship between current, welding time, lift height, and stud movement determines how the joint forms. **Stage 4: Plunge and post-welding current control** Depending on the programmed sequence, the equipment may provide a separately controlled current stage during or after the stud’s plunge into the molten pool. The exact function of this stage depends on the SAW-3600 control configuration. The term _upset current_ should therefore be used only if it matches the parameter’s actual function in the equipment documentation. It should not be confused with the mechanical plunge movement itself. ## 2. Pilot Current and Pilot Time Pilot current and pilot time affect the beginning of the welding cycle. If the arc does not start consistently, changing the main welding current may not solve the underlying problem. Pilot current is the current applied during the pilot arc stage. Pilot time determines how long that stage lasts. For galvanized steel, the coating and surface condition can influence arc initiation. Oil, dirt, and other contaminants may also affect consistency. However, a higher pilot current or a longer pilot time is not automatically better. The aim is to establish a stable arc without introducing unnecessary heat. ### Equipment settings | Parameter | Minimum | Default | Maximum | Unit | | Pilot time | 10 | 50 | 100 | ms | | Pilot current | 15 | 50 | 150 | A | The default pilot current is 50 A, and the default pilot time is 50 ms for the configuration described here. These values provide a starting point rather than a fixed recommendation for every application. When adjustment is needed, consider pilot current and pilot time together. Make controlled changes and observe whether arc initiation becomes more consistent. ## 3. Welding Current and 󠀁[Welding Time](https://www.hongbaiweld.com/tag/322)󠁿 Once the main arc is established, welding current and welding time become the principal electrical parameters controlling the melting process. Welding current determines the current delivered during the main welding stage, while welding time determines how long it is applied. Their combined effect influences the melting of the stud end and base material, the size of the molten pool, and the resulting weld profile. ![Main welding arc melting the end of a metal stud and the surface of a steel workpiece]( https://www.hongbaiweld.com/wp-content/uploads/2026/10/2026101606045915.jpg) Main welding current and duration determine the energy delivered to the stud and workpiece. If the energy input is too low, the stud may not fuse adequately with the workpiece. If it is too high, the weld may produce excessive spatter or an oversized collar. Thin sheet metal is particularly sensitive to excessive heat input. ### Equipment settings | Parameter | Minimum | Default | Maximum | Unit | | Welding time | 5 | 20 | 100 | ms | | Welding current | 100 | 300 | 2,000 | A | The values above describe the available settings for the equipment configuration covered by this guide. The appropriate working values depend on the stud and the actual welding application. ### Using stud diameter as an initial reference For preliminary trials, the following empirical relationships can provide a starting point:   **Estimated welding current** Welding current ≈ Stud diameter (mm) × 100 A For a 6 mm stud: 6 × 100 = 600 A This gives an initial reference of approximately 600 A.   **Estimated welding time** Welding time ≈ Stud diameter (mm) × 3–5 ms For a 6 mm stud: 6 × 3–5 = 18–30 ms   A starting trial value near 24 ms may be appropriate, depending on the material and equipment configuration. These formulas are practical estimates, not universal rules. Two applications using the same stud diameter may require different settings because of differences in material, sheet thickness, stud-end geometry, surface coating, and arc conditions. When developing a welding procedure, change the current or time in controlled increments and compare the results. Adjusting several parameters at once makes it much harder to identify what actually improved or worsened the weld. ## 4. Upset Time and 󠀁[Upset Current](https://www.hongbaiweld.com/tag/323)󠁿 Upset time and upset current are available on certain welding systems, but their functions depend on the equipment’s control sequence. Upset time refers to the duration of the designated stage. Upset current refers to the current applied during that stage, where independent current control is supported. These terms should be checked against the actual equipment configuration. In particular, a separately controlled current during stud plunge is not necessarily the same as a post-welding holding current. ![Finished metal stud welded to a steel plate with the weld base visible for inspection]( https://www.hongbaiweld.com/wp-content/uploads/2026/10/2026101606010699.jpg) The finished weld should be assessed alongside the selected process settings and the application requirements. ### Equipment settings | Parameter | Minimum | Default | Maximum | Unit | | Upset time | 0 | 5 | 20 | ms | | Upset current | 100 | 200 | 1,500 | A | ### Reference settings for different applications The following values are preliminary references supplied for this guide. They should be verified through trial welding before being used in production. | Application | Reference Upset Time | Reference Upset Current | | T-type stud | 3 ms | — | | Thin sheet metal (≤ 0.8 mm) | 5 ms | 100–200 A | | Studs M5 and larger | 6–8 ms | 200–300 A | | General reference, depending on stud size | 5–12 ms | — | The general reference of 5–12 ms is not the same as the equipment’s default setting of 5 ms or its available range of 0–20 ms. The first is an application guideline; the others describe the equipment settings. When evaluating these parameters, look at the complete weld rather than a single visual feature. Stud alignment, weld collar formation, spatter, sheet deformation, and joint strength all matter. A weld that looks acceptable on the surface may still require mechanical testing to confirm its integrity. ## 5. Reference Parameters for Common Stud Types The following table lists the reference combinations provided for several stud types. | Stud Type | Low Current (A) | Low-Current Time (ms) | High Current (A) | High-Current Time (ms) | | T-type stud | 35 | 30 | 220 | 15 | | M5 stud | 35 | 30 | 450 | 22 | | M6 stud | 35 | 30 | 600 | 26 | | M6 large-cap stud | 50 | 50 | 800 | 40 | These values are intended as references for the corresponding equipment and application, not as universal settings for all stud welding systems. The labels _low current_ and _high current_ follow the supplied reference data. They should not automatically be interpreted as pilot current and main welding current without confirmation from the original equipment documentation. Before using these settings, check the stud geometry, base material, sheet thickness, lift height, and operating mode. During commissioning, begin with a suitable reference procedure and make gradual adjustments. Trial welds should be inspected before the settings are accepted for production. ## 6. Lift Height and Target Arc Voltage Current and welding time are only part of the process. Lift height and target arc voltage also affect arc conditions and should be considered when troubleshooting inconsistent welds. ### Lift height Lift height is the distance the welding gun raises the stud from the workpiece to establish the arc gap. The reference setting range is **0.5–4 mm**, with **1–1.5 mm** suggested as an initial reference where appropriate. An unsuitable lift height can affect arc stability and weld formation. Increasing the lift height does not necessarily improve the result, so it should be evaluated alongside the current, welding time, stud geometry, and control mode. ### Target arc voltage For equipment operating in a constant-power control mode, target arc voltage is one of the parameters used to regulate the welding process. The reference range provided for this guide is **20–26 V**. This should not be treated as a universal setting for every power source or application. The appropriate value depends on the equipment design, control algorithm, stud type, and welding conditions. When adjusting lift height or target arc voltage, compare the actual weld results rather than relying on the setpoint alone. ## 7. A Practical Approach to Parameter Optimization ![Industrial stud welding equipment control panel used to adjust welding process parameters](https://www.hongbaiweld.com/wp-content/uploads/2026/10/2026101605403674. png) Parameter adjustment should be followed by test welding and verification of the finished joint. A good starting point is to confirm the stud specification, base material, sheet thickness, surface coating, and required joint strength. These details help determine which reference procedure is appropriate. Next, establish initial settings using the equipment manual and available process data. Conduct trial welds on representative workpieces under stable conditions, changing one parameter at a time wherever practical. Inspect the resulting welds for stud alignment, collar consistency, excessive spatter, deformation, and burn-through. Where required, use mechanical testing or other suitable inspection methods to verify joint integrity. Once an acceptable parameter combination has been established, record the settings together with the material conditions, equipment configuration, and inspection results. Repeat the trials under representative production conditions to check that the results remain consistent across multiple welds. At Hongbai Technology, we develop stud welding equipment and intelligent welding automation solutions for industrial manufacturing. Our SAW-3600 series is part of our stud welding equipment portfolio, supporting applications where reliable process control and repeatable weld quality are important. ## Why Aluminum Stud Welding Requires AC/DC Technology: Understanding the Difference Between Aluminum and Steel Welding - Link: https://www.hongbaiweld.com/news/interior-accessories3919.html - Published: 2026-10-13T17:08:57+08:00 - Author: zhouhui ## Aluminum welding is not just about increasing current With the rapid development of electric vehicles (EVs) and lightweight automotive structures, aluminum has become increasingly important in Body-in-White (BIW) manufacturing. However, welding aluminum is fundamentally different from welding steel. Many manufacturers find that a conventional DC [stud welding system](https://www.hongbaiweld.com/tag/144) can achieve stable results on steel studs but struggles when applied to aluminum components. Problems such as unstable arc behavior, porosity, insufficient fusion, and low pull strength often occur. The reason is not simply insufficient welding current. The real challenge comes from the unique physical properties of aluminum: * High thermal conductivity * Low melting temperature * High melting point oxide layer * Rapid heat dissipation These characteristics determine that **aluminum stud welding requires more precise control of heat input and current direction.** This is why advanced **AC/DC stud welding technology** has become an important solution for aluminum automotive applications. ![AC/DC stud welding system for EV aluminum body welding and automotive manufacturing]( https://www.hongbaiweld.com/wp-content/uploads/2026/10/2026101307401424.png) # Aluminum vs Steel: Why the Welding Process Is Completely Different Although aluminum and steel can both be joined through arc welding, their melting behavior is very different. | Property | Steel | Aluminum | Impact on Welding | | Melting point | Approx. 1500℃ | Approx. 660℃ | Aluminum melts much earlier | | Oxide layer | Thin oxide film | Al₂O₃ oxide layer, melting point approx. 2050℃ | Oxide layer is difficult to break | | Thermal conductivity | Approx. 50 W/(m·K) | Approx. 237 W/(m·K) | Heat dissipates much faster | | Density | 7.8 g/cm³ | 2.7 g/cm³ | Lightweight structure advantage | | Molten pool stability | Relatively stable | Difficult to maintain | Requires precise heat control | The biggest challenge is the aluminum oxide layer. Although aluminum itself melts at around 660℃, the aluminum oxide layer on the surface requires temperatures above 2000℃ to break down. This means: **Before the aluminum base material can melt properly, the oxide layer must first be effectively removed.** Without breaking this barrier, the stud and base material cannot form a strong metallurgical bond. # Why DC Stud Welding Has Limitations on Aluminum Traditional DC stud welding systems are highly effective for steel applications. However, when welding aluminum, fixed current direction creates several challenges. ## 1. Difficulty Breaking the Aluminum Oxide Layer In DC welding, the current direction remains constant. The arc heat distribution is therefore fixed, making it difficult to effectively disturb and remove the Al₂O₃ oxide layer. The result may include: * Incomplete fusion * Weak weld strength * Stud detachment during pull testing --- ## 2. Unbalanced Heat Distribution The polarity of DC welding determines where most heat is generated. ![DC stud welding polarity and heat distribution analysis for aluminum welding process]( https://www.hongbaiweld.com/wp-content/uploads/2026/10/2026101308213168.png) Depending on polarity: * Too much heat on the base material may cause thin aluminum sheets to burn through. * Too much heat on the stud side may result in insufficient penetration. For aluminum automotive components, especially thin sheets, maintaining the correct balance between stud melting and base material melting is critical. --- ## 3. Rapid Heat Dissipation Aluminum conducts heat almost five times faster than steel. During welding: * Heat quickly spreads away from the welding area. * The molten pool exists for a very short time. * Insufficient fusion may occur before the stud fully penetrates. This makes aluminum welding much more sensitive to welding parameters. # How 󠀁[AC/DC Stud Welding](https://www.hongbaiweld.com/tag/314)󠁿 Solves 󠀁[Aluminum Welding](https://www.hongbaiweld.com/tag/315)󠁿 Challenges The key advantage of AC/DC stud welding technology is: **The ability to control current direction during the welding process.** Unlike traditional DC systems, AC/DC welding systems can alternate between positive and negative current output. ![DC stud welding limitation for aluminum oxide layer removal](https://www.hongbaiweld. com/wp-content/uploads/2026/10/2026101307581149.jpg) This provides three major advantages. ## 1. Precise Control of Heat Distribution By adjusting positive and negative current ratios, engineers can control how heat is distributed between: * The aluminum stud * The aluminum base material For example: **Thin aluminum sheet applications** → Reduce heat input into the base material → Lower burn-through risk **Thicker aluminum structures** → Increase base material penetration → Improve weld strength This flexibility allows one welding system to adapt to different aluminum structures. --- ## 2. Faster Oxide Layer Breaking Advanced AC/DC stud welding systems use rapid current switching technology. The alternating current direction creates a controlled thermal effect on the oxide layer, helping the arc penetrate the aluminum surface more effectively. Combined with high-speed digital current control, the welding process becomes more stable and repeatable. --- ## 3. Improved Molten Pool Control Aluminum requires careful control of molten pool behavior. Multi-pulse AC welding technology can improve: * Arc stability * Molten pool fluidity * Fusion consistency * Weld strength This is especially important for: * EV aluminum body structures * Lightweight vehicle components * Aluminum alloy panels # HEAS AC/DC Stud Welding System: Designed for Aluminum Applications Hongbai HEAS AC/DC stud welding system combines: * High-frequency inverter technology * DSP + FPGA digital control * AC/DC programmable output * Multi-pulse welding process * High-speed current response The system supports flexible welding processes: | Welding Mode | Application | | Single pulse DC | Standard steel stud welding | | Multi-pulse DC | Advanced steel applications | | Multi-pulse AC | Aluminum stud welding | | Custom waveform control | Complex material applications | # Flexible Welding Waveform Control HEAS supports multi-stage welding parameter adjustment. Engineers can independently configure: * Current value * Welding time * Current direction * Pulse sequence This allows customized welding waveforms for different aluminum materials and component designs. # Requirements for High-Quality Aluminum Stud Welding AC/DC capability is the foundation, but successful aluminum stud welding also requires proper process conditions. ## Aluminum Material Compatibility Recommended: * Aluminum studs * Aluminum base materials * Stud diameter: 3–10mm * Sheet thickness: ≥0.8mm ## Shielding Gas Protection Aluminum welding requires shielding gas protection. Typically: * Argon gas * Purity ≥99.99% Shielding gas prevents oxidation during the molten state and reduces porosity. ## Gas-Shielded Welding Gun For aluminum applications, a gas-protected stud welding gun is required. The gun creates a local shielding environment around the welding area to protect the molten pool. # AC/DC Stud Welding: A Key Technology for Future 󠀁[EV Manufacturing](https://www.hongbaiweld.com/tag/316)󠁿 As automotive manufacturers continue moving toward lightweight structures and aluminum body designs, traditional steel welding technologies cannot fully meet new requirements. The challenge of aluminum stud welding is not solved by simply increasing current. It requires: * Correct heat distribution * Controlled current direction * Stable arc behavior * Precise digital control The **AC/DC stud welding system** provides the flexibility needed for modern automotive manufacturing, enabling reliable welding of aluminum structures while maintaining compatibility with traditional steel applications. For EV manufacturers and automotive suppliers, the future of lightweight vehicle production depends not only on stronger materials, but also on smarter welding technology. **Smart Welding. Stronger Future.** ## Dual-Loop Control in Resistance Spot Welding: Why Welding Current and Electrode Force Must Work Together - Link: https://www.hongbaiweld.com/news/interior-accessories3895.html - Published: 2026-10-09T14:13:26+08:00 - Author: zhouhui In resistance spot welding, a stable weld is not simply a matter of setting the correct current. The result depends on how welding current, electrode force, and weld time interact throughout the welding cycle. This becomes particularly important in automotive manufacturing, where a single production line may handle different sheet thicknesses, galvanized steels, and high- strength materials. A welding schedule that performs well on one material combination may produce excessive spatter or insufficient weld nugget formation on another. Increasing the current is not always the answer. Nor does applying more electrode force necessarily improve the weld. What matters is maintaining the right relationship between electrical heat generation and the mechanical conditions at the joint. This is the principle behind **dual-loop control in resistance spot welding**. By regulating welding current and electrode force through coordinated feedback control, the system can respond more effectively to process variations and help maintain consistent welding performance. ## How Dual-Loop Control Works Dual-loop control refers to two feedback control functions operating within the welding system: closed-loop welding current control and weld force control. Although they serve different purposes, both influence the conditions under which the weld nugget forms. | Control function | Feedback or monitoring variable | Control mechanism | Primary objective | | Welding current control | Actual welding current | Inverter output regulation | Maintain the commanded current despite electrical load variations | | Weld force control | Electrode force, where sensor feedback is available | Pneumatic proportional valve or electric servo actuator | Regulate electrode force and monitor force-related process conditions | | Adaptive coordination | Application-specific process feedback and programmed welding schedules | Control logic and parameter adjustment | Match welding conditions to qualified material and joint requirements | The current control loop monitors the actual welding current and compares it with the programmed target. The controller adjusts the inverter output to reduce deviations, helping maintain the required current as electrical conditions change. The force control loop regulates electrode force through a servo mechanism and, where equipped, monitors the actual force using sensor feedback. This helps maintain the intended mechanical conditions during electrode contact and welding. ![Dual-loop control diagram showing welding current feedback and electrode force regulation in resistance spot welding](https://www.hongbaiweld.com/wp-content/uploads/ 2026/10/2026100902161535.png) Stable resistance spot welding depends on coordinated control of welding current, electrode force, and welding time. Neither loop replaces the other. Stable current cannot compensate for an unsuitable electrode force, just as accurate force control cannot make up for an inadequate welding schedule. The challenge is to coordinate both variables according to the materials, joint configuration, and required welding conditions. ## Why Current Control Alone Is Not Enough Resistance spot welding generates heat as current passes through the resistance of the workpiece and its contact interfaces. The amount and distribution of heat influence the formation and growth of the weld nugget. In practice, however, the electrical resistance of a joint is not constant. Surface coatings, electrode wear, contact conditions, and material combinations can all affect the welding process. When heat input becomes excessive for the prevailing conditions, molten metal may be expelled from the joint. This expulsion, commonly referred to as weld spatter, can contaminate electrodes, increase cleaning requirements, and affect production stability. At the other extreme, insufficient heat input may result in an undersized weld nugget or inadequate joint strength. Closed-loop current control helps the power source maintain the commanded current more consistently. Hongbai’s inverter resistance spot welding systems combine digital control with current feedback to regulate electrical output as operating conditions change. This is particularly valuable in automated production, where repeatability matters more than achieving a satisfactory result on a single weld. However, current regulation alone does not guarantee weld quality. The current target, welding time, electrode force, and material-specific process window must still be established through appropriate welding trials and validation. ## Electrode Force: The Other Half of the Process Electrode force affects the contact conditions between the electrodes and workpieces, influencing current density, contact resistance, and the development of the weld nugget. If the force is too low for the selected welding schedule, localized heating and expulsion may become more likely. If it is too high, the resulting contact conditions may reduce resistance heating and make nugget formation more difficult under otherwise unchanged settings. This is why force should not be treated as a fixed mechanical setting that can be ignored once the welding gun has been installed. Hongbai provides pneumatic servo and electric servo solutions for different resistance spot welding configurations. Proportional-valve-controlled pneumatic systems support force regulation in applicable high-frequency systems, while electric servo actuators provide programmable force control and monitoring in medium-frequency and aluminum- joining configurations. ![Resistance spot welding electrodes applying controlled force to metal sheets during welding](https://www.hongbaiweld.com/wp-content/uploads/2026/10/2026100902384056- e1791513609105.jpg) Controlled electrode force helps maintain stable contact conditions throughout the welding cycle. For applicable electric servo systems, electrode force can exceed 900 kg, depending on the configuration. The practical advantage is not simply the ability to apply greater force. It is the ability to regulate force according to the requirements of the welding process and monitor whether the system is operating as intended. ## From Dual-Loop Control to Adaptive Welding Feedback control and adaptive control are related, but they are not the same thing. A closed-loop controller corrects deviations in a controlled variable, such as welding current. An adaptive strategy goes further by adjusting the welding settings or control strategy in response to relevant changes in process conditions, within defined operating limits. For example, a production line may need to weld different sheet thicknesses or material combinations at the same station. These combinations can require different welding schedules because their electrical and thermal characteristics are not identical. | Production condition | Control consideration | Intended process benefit | | Different sheet thicknesses | Select a qualified current-force-time schedule for each material stack-up | More consistent weld formation across product variants | | Galvanized steel | Balance heat input, electrode force, and coating-related process effects | Reduce the risk of expulsion and improve process stability | | High-strength steel | Maintain suitable welding conditions for the specific steel grade and joint | Support repeatable nugget formation | | Changes in electrical load | Use current feedback to regulate actual output | Reduce sensitivity to electrical load variations | | Mixed-model production | Apply validated schedules and appropriate force settings | Reduce repeated manual adjustment during changeovers | With an appropriately configured adaptive control system, current and force settings can be coordinated with the selected welding schedule to suit the specific application. This can reduce the need for repeated manual adjustments when changing between qualified production conditions. The distinction matters: adaptive control does not mean that a machine can automatically weld any material combination without prior setup. Reliable results still depend on suitable parameter windows, process qualification, electrode condition, and the capabilities of the control system. When these requirements are addressed, dual-loop control provides a stronger foundation for flexible production, particularly in automotive body manufacturing, where several material grades and thicknesses may be used within the same assembly. ## Hongbai’s Resistance Spot Welding Technology Hongbai applies inverter power technology, digital control, and servo actuation across different resistance spot welding solutions. The choice of system depends on the required output, force-control method, material characteristics, and production conditions. | System series | Main technology | Force-control configuration | Typical application focus | | SHF high-frequency inverter DC | 10 kHz inverter technology, full-bridge soft switching, DSP-based digital control | Pneumatic servo with proportional-valve control | Applications requiring flexible force regulation across different material conditions | | MF medium-frequency inverter DC | Full-digital power supply, high-speed DSP control, closed-loop current regulation, secondary rectification | Electric servo actuator with programmable force control and monitoring | Automotive body welding and demanding production applications | | High-power medium-frequency aluminum-joining system | 1 kHz or 2 kHz welding transformer configurations, high-power output | Electric servo force control and monitoring, depending on configuration | Aluminum resistance spot welding and other high-current joining applications | The SHF high-frequency inverter DC system combines 10 kHz inverter technology, full- bridge soft switching, and DSP-based digital control. Its pneumatic servo configuration supports force regulation and adaptive welding applications requiring flexibility across different material conditions. ![Hongbai resistance spot welding equipment for automotive manufacturing and metal joining](https://www.hongbaiweld.com/wp-content/uploads/2026/10/2026100903202850. jpg) Different resistance spot welding configurations address different material, force, and production requirements. The MF medium-frequency inverter DC system combines a full-digital power supply, high-speed DSP control, closed-loop current regulation, and secondary rectification. With electric servo actuation, it supports programmable electrode force and real- time force monitoring in applicable configurations. Electrode force can exceed 900 kg, depending on the system design. For aluminum joining, Hongbai also offers high-power medium-frequency systems designed for the demanding electrical and thermal requirements of aluminum resistance spot welding. Depending on the configuration, these systems can deliver welding currents of up to 60,000 A and support single- or dual-transformer arrangements. Each configuration addresses a different set of production requirements. Selection should be based on material type, sheet stack-up, joint geometry, electrode design, required cycle time, and the available welding process window. ## What Manufacturers Gain from Better Coordination The value of dual-loop control becomes clear when it is considered in the context of daily production. More stable current and force conditions can help reduce variations in weld formation and lower the risk of spatter. Reduced spatter may also mean less electrode cleaning, fewer interruptions, and less downstream rework. For manufacturers running multiple vehicle models or material combinations, programmable servo force and qualified welding schedules can make production changeovers more manageable. Current feedback and force monitoring also provide useful information for troubleshooting when the welding process begins to drift. These benefits are connected. Better process control can support better weld consistency, while improved consistency can reduce the time and resources spent correcting defects. The actual improvement depends on the application and must be verified through welding tests and production data. Dual-loop control is not a substitute for proper electrode maintenance, joint preparation, or quality assurance; it is a way to manage important process variables more precisely. ![Robotic resistance spot welding in automotive production with controlled welding parameters](https://www.hongbaiweld.com/wp-content/uploads/2026/10/202610090353362. jpg) Coordinated process control can help manufacturers improve weld consistency and manage production variation. ## A More Controlled Approach to Resistance Spot Welding As automotive structures incorporate more high-strength steel, galvanized sheet, and aluminum, maintaining a stable resistance spot welding process becomes increasingly demanding. The answer is not simply to increase welding current or electrode force. It is to understand how these variables interact and control them accordingly. By combining closed-loop current regulation with servo-based force control and application- specific adaptive strategies, Hongbai Technology helps manufacturers build more stable and flexible resistance spot welding processes. For production engineers and automation teams, the key question is not just whether a welding system can deliver the required current or force. It is whether the system can maintain the right conditions throughout the welding cycle and across the demands of real production. **Hongbai Technology develops resistance spot welding solutions for automotive manufacturing and other industrial applications. Contact our team to discuss your materials, welding requirements, and process integration needs.** [www.hongbaiweld.com](https://www.hongbaiweld.com/)