A quick and proven joining process that utilizes high-speed rotation and axial pressure to produce frictional heat to join dissimilar materials.
Rotary friction welding is a solid-state joining process that utilizes frictional heat to join two materials. It does this by axially rotating the two parts against each other under pressure and creating frictional heat. The rotational energy and pressure generate heat at the interface under the material’s melting point, making it a solid-state joining process. Typically, the joining process has three phases: Pre-Heating, Heat, and Forging.
Before welding, the rotary friction welding machine butts the two materials without rotation and measures the components, zeroing a distance measuring counter. If the two components are not within a proper length tolerance, the machine will not weld the part and notify the operator that the parts are out of length tolerance.
1. Pre-Heat Phase
The materials are subjected to light pressure and rotational energy, which creates frictional heat. The light pressure is a light axial load, and the rotational energy is in the form of low or high-speed RPM. This Phase “pre-heats” the dissimilar materials. This phase also burns off any oils and oxides at the weld interface and is typically controlled by time.
2. Heat Phase
In this phase, a higher axial load is applied while maintaining the parts’ low – or high-speed rotation against each other. Thus, more frictional heat is created, and the materials become plasticized. The material at the interface begins to squeeze out, which is called “flash.” Any remaining oxides or contaminates at the weld interface are displaced into the flash. This phase is typically controlled by distance. Once a pre-determined distance or material length loss is achieved, the machine goes into the forging phase.
3. Forge Phase
In this phase, the low or high-speed rotation is stopped, and an even higher axial load is applied to the parts. Due to the absence of rotational energy, frictional heating stops, and the parts begin to cool under the higher axial load. The dissimilar materials are forged together while cooling, creating a strong bond.
A Computer-Controlled Process
The computer monitors axial load, RPM, and length variables. The machine will notify the operator to act if any key variable is outside a pre-determined window.
- A full-strength joining process with complete penetration through the full cross-section of the weld with no oxides, porosity, or contamination at the weld interface.
- A narrow Heat Effective Zone (HAZ), which limits affecting the base material properties.
- The ability to weld dissimilar materials such as stainless steel to carbon steel, copper to aluminum, etc.
- A quick and proven joining process that utilizes high-speed rotation and axial pressure to produce frictional heat to join dissimilar materials.
- An easily automated process.
