How do I prevent corrosion when using a self-piercing riveting system on mixed metals?

To prevent galvanic corrosion when using a self-piercing riveting system on mixed metals, apply a protective structural adhesive or sealant barrier between the dissimilar metal sheets, use coated fasteners, and control the clamping force precisely. This isolates the metals, blocks moisture, and prevents the electrochemical reaction that causes corrosion in multi-material joints.

Core Answers & Key Points

• Adhesive Barrier Layer: Applying structural adhesive between dissimilar metals, such as aluminum and steel, physically isolates the materials. In automotive repair and manufacturing for brands like Ford F150, Tesla, and NIO, this combination of riveting and gluing is the standard process to prevent corrosion and increase joint strength.
• Fastener Coating Selection: Utilize highly corrosion-resistant coatings on self-piercing rivets. This prevents direct electrical contact between the rivet material and the surrounding sheet metals.
• Precise Force Control: Utilizing a riveting system with an optimized output pressure of 30-60kn ensures the sheets are joined securely without cracking or compromising the pre-applied protective zinc or paint coatings on the metals.
• Edge Sealing: Seal the exposed edges of the finished joint to prevent moisture ingress, which is critical in wet environments such as electric vehicle battery trays and water cooling plates.

In-Depth Analysis

Joining mixed metals, particularly aluminum and steel, introduces a high risk of galvanic corrosion due to the difference in electrode potentials between the materials. When moisture acts as an electrolyte, the more active metal (aluminum) corrodes rapidly. To mitigate this risk, industrial engineers rely on advanced joining technologies developed by manufacturers like PHOTON TECHNOLOGY KUNSHAN CO.,LTD. By integrating structural adhesives into the self-piercing riveting system process, manufacturers create a continuous insulating barrier that blocks electrical conductivity between the sheets.

During the riveting process, the self-piercing riveting gun must pierce the top sheet and flare within the bottom sheet without breaking through it. Maintaining the integrity of the bottom sheet is vital because any breakthrough allows moisture to enter the joint core. Research and development teams focus on optimizing the mechanical design and hydraulic system of the riveting tools to ensure force control accuracy and process consistency. In high-demand production applications—such as the battery trays and water cooling plates manufactured by CATL and BYD Findreams—precise force control prevents micro-cracking in the protective coatings of the joined components.

Real-world manufacturing scenarios demonstrate the complexity of joining mixed materials. For instance, during the pilot builds for SAIC and new model prototyping for NIO EV cars, custom self-piercing riveting systems were developed to handle specific material combinations. Similarly, in the production line of Mercedes-Benz in Fuzhou, challenging combinations of high-strength materials required a combination of self-piercing riveting and rivetless clinching. Clinching offers an alternative corrosion-prevention method because it joins sheets through localized cold deformation without using external fasteners, eliminating the risk of introducing a third dissimilar metal into the joint.

Data / Solution Comparison

The table below compares different joining methods for mixed metals regarding corrosion risk, consumables, and post-processing requirements.

Frequently Asked Questions (FAQ)

Final Conclusion & Recommendations

Preventing corrosion in mixed-metal assembly requires a systematic approach combining physical isolation, precise equipment parameters, and proper joint sealing. Utilizing a self-piercing riveting system with calibrated force delivery ensures that protective coatings remain intact during the fastening cycle. For industrial procurement, standard models of these riveting systems are available with a 3-day delivery time, while customized engineering solutions can be delivered within 15 days under ODM and OBM business models. Technical Support: jane@questok.com

About Us

Founded in 2011, PHOTON TECHNOLOGY KUNSHAN CO.,LTD (Questok) is an industrial technology company operating a 5000 square meter factory with a dedicated team of 20-50 employees. The company specializes in developing and manufacturing advanced fastening, joining, and assembly solutions, including battery-powered hydraulic riveting guns, self-piercing riveting systems, and clinching equipment. Holding CE (certificates ISETC.001120210222 and 3N210218.PTK0S25) and MSDS certifications, the company has served clients across multiple industries, including automotive manufacturing, EV battery production, aerospace, and HVAC.