Spot Welding

Online process monitoring on static welding machines
A welding machine can be very easily retrofitted with Kistler piezoelectric force-strain sensors. The measuring point can be on the armature, near the electrode, or at a suitable point on the frame of the machine.

For specialized machines or welding systems with special electrode designs (e.g. projection welding machines), and for dimensional reasons, there is the option of measuring force with integrated load washers. This involves mounting one or more force sensors in machine components such as flanges, in connecting rods of pneumatic or electric servomotors, or behind platen type electrodes.

The picture on the left hand side shows an indirect force measurement with a Kistler strain sensor, Typ 9232.

Direct in-situ electrode force measurement (calibration) on welding guns and welding machines
Robot spot welding guns have to be tested during product development in order to test methods or measure and check operation after installation. The electrode clamping force can be calibrated with an extremely high level of repeatability with the Typ 9831... welding force calibration transmitter as reference unit. The piezoelectric force sensor's high factor of safety against overload is also a considerable advantage, since on test rigs, for example, the electrodes can meet asymmetrically, giving rise to high impact forces.

Offline force measurement in cap milling stations
Late detection of defects in the resistance spot welding guns used in body construction or of incorrect process parameters can lead to costly production rejects. The Typ 9833... welding force test transmitter was designed for regular force measurement on production lines. The welding robots test the electrode force automatically on the basis of the number of cycles and load. The force measurement system is integrated into a service station, and during operation the welding robot runs through a regular service cycle involving re-milling the electrode caps as required.