The hot upset forming and riveting process uses heat and pressure to form the fastener. The material being formed becomes malleable and collapses under pressure applied by the powerhead. Using this process, it is possible to form a round fastener into a square hole, creating very high torque joints. This process is excellent for forming parts that will incur high vibrational fatigue.
Hot upset can be used for metal gathering. An electric current is run through a material to heat it to the point of making it malleable to create a mass gathered at a desired point.
For hot upset riveting, an electric current is run through a tenon in a specific controlled heating and cooling cycle. This cycle heats the tenon, which allows it to be formed to a desired shape.