the most important parameters in the lfw process are friction pressure, forging pressure, burn-off, frequency, amplitude, stick out and perhaps their respective ramps or variation against time. "friction pressure" is that developed between the parts to be welded during the oscillation period. "forging pressure" is that maintained for a short period of time after the oscillation is stopped and is typically around 20% greater than the "friction pressure". "burn-off" is the change in length of the workpiece as its substance is turned into "flash" – material that escapes around the weld. "frequency" and "amplitude" describe the movement of the oscillator and hence of one of the parts to be welded. "stick out" is the linear measurement of the amount of material that the parts have protruding from the tooling (oscillator and forging tooling).