Hot Upset Forming & Riveting

Orbitform's Hot New Riveting Process

Posted on 11/27/2013 | by The Orbitform Blog Team


Here at Orbitform, we recently developed a unique riveting process called Hot Upset. This rivet/forming solution uses force and heat to form rivets or part tenons, providing greater strength, increased hole-fill, improved resistance to push-pull forces, and an overall tighter joint, due to material contraction during cooling.


Similar to electro-forging, the headed material becomes malleable and collapses under pressure applied by the Powerhead. With this process it is possible to form a round fastener into a square hole, creating a high-torque joint. Our customer, an automotive part manufacturer, needed to assemble a product with hardened rivets, each with a long tenon stick-out. To meet their production requirements, we needed to form two rivets per machine cycle. We examined both Orbital and Radial Forming options in our applications lab, but due to the extreme hardness of the rivets, final form characteristics did not meet our customer’s specifications. Also, some samples showed signs of cracking, which was unacceptable in this application. We then tested our Hot Upset forming solution, which resolved the forming challenges.


Orbitform designed and built a custom Hot Upset system. The design included two standard Orbitform modular Powerheads, the same Powerheads used in our Orbital, Radial, and Roller Forming products. Using standard Powerheads instead of traditional weld cylinders eliminated the need for an external air/oil tank and intensification valve. To stabilize the customer’s part during the forming process, the system was outfitted with a part clamping pressure pad. To verify a quality form, process monitoring included an LVDT, load cells, and Powerhead advance and retract sensors. The customer’s safety specifications included light curtains, guarding, and palm button activation.


Hot Upset typically has a 3-4 second cycle time, which is generally slower than Orbital, Radial or Impact Riveting. In addition, hot parts require special handing considerations. We offer both AC and DC Hot Upset systems. In the case of our customer, we built a DC system for its power consumption savings versus the lower initial cost of an AC system. DC powered systems are more efficient and precise than their AC counterpart but come at a higher price. Cost of ownership includes power consumption and tooling electrodes. Hot Upset systems also require a chiller to maintain optimal tooling temperature.


Our Hot Upset process could help you in your assembly process. At Orbitform, we are experts in assembly processes. To learn more about permanent part assembly or download our full white paper text. Visit our website at or call 800-957-4838 to speak to an expert today. Orbitform…solutions delivered.