Kistler has introduced piezoelectric sensors to its systems for monitoring cold forming processes off-line and on-line.

Clinching and riveting are replacing welding in the manufacture of an increasing number of sheet metal assemblies including car doors, bonnets and tailgates in both aluminium and steel. On-line Monitoring of the force needed for plastic deformation during the clinching process can detect wear in the clinching tool, punch or swage breakage, deviations in the dimensions or number of parts and incorrect machine setting. Continuous monitoring makes the clinching cycle transparent for QA recording and identifi es any long-term changes in machine performance.

Off-line checking of the clinching tongs using a Kistler hand-held calibration transmitter can be used to monitor and, if necessary, adjust the on-line system sensors.

A similar method can be applied to monitor pop and blind riveting machines to eliminate faults in the process.

Data from the monitoring sensors can be fed to a central production control system or processed locally using Kistler CoMo Net or CoMo View process monitoring systems. Both systems can provide a signal to activate a faulty unit rejection mechanism.