When a target or actual gap between two components in a machine changes, it could be necessary to adjust it.
The disadvantage of classical flat washers that are ground exactly to the required gap, is that they need to be inserted mechanically. It is not always possible to adjust them as finely as required and the predefined gap cannot be changed any more.
This is different in the case of the piezo-based PIRest active shims, which only need to be inserted once and can actively adjust or readjust the gap between two components.
Conventional piezoceramic actuators were not suitable for this purpose. The electrical voltage (offset voltage) at the actuator needs to be maintained as long as the displacement is required – a considerable disadvantage for the lifetime of the actuator and the equipment of the machine, which also requires an additional and stable power supply.
Although the PIRest technology is based on piezo actuators, it nevertheless maintains a stable displacement with nanometer accuracy after adjusting even without offset voltage.