Vibration welding process

Four different phases can be distinguished in the vibration welding process, namely the solid friction phase, the transient phase, the steady-state phase and the cooling phase.

The phases of the vibration welding process

In the solid friction phase, the heat generated due to frictional energy between the two surfaces (frequency of vibration, amplitude, and pressure) causes the material to heat up and melt.

In the second phase the molten polymer layer increases due to shear heating in the viscous (melt) phase. Heating decreases as the thickness of the viscous layer increasing.

In the third phase, the rate at which melt is formed becomes equal to the outward flow rate (film drainage) and this comes to a steady state (the thickness of the molten layer becomes constant). Vibrations are stopped at this point.

The polymer melt starts to cool, the cooling phase, and solidification results at the interface of the joint. Film drainage will continue while the joint is held under pressure. When solidification is complete the pressure is withdrawn and the joint is formed.

Process parameters

Large batch sizes are possible. Usually products larger than 200 mm (8 in) are joined with this technique.

Typical process parameters are:

- frequency: 100-400 Hz
- amplitude: 0.5-2.5 mm (0.02-0.10 in)
- cycle time: 10 seconds
- weld pressure: 0.5-5 MPa (70-700 psi)

Materials

Most DSM-thermoplastics, such as Stanyl, Akulon, Arnite, and Xantar, can be vibration welded,. Amorphous materials such as Xantar, are more easily vibration welded than semi-crystalline polymers. The process is not suitable for very flexible materials such as Arnitel.