WE Colloquium: Robert Cohen, Using Adaptive Controls to Improve Resistance Weld Quality and Reduce Reliance on Destructive Testing

Abstract

Insights are provided as to how manufacturers that perform resistance welding employ adaptive controls to increase weld quality assurance, increase productivity, and reduce production downtime.  Included are discussions about how adaptive strategies are applied to address part fit-up, surface contamination, flattening electrodes and shunting problems that have traditionally plagued resistance welding operations.  Also presented are how aerospace manufacturers realize 25% production throughput increases by employing alternate testing methods to eliminate destructive production lot testing.  This includes an overview as to how manufacturers that must operate in compliance with the MIL-SPEC (AWS D17.2 ) use Process Capability measurements to demonstrate that production welds meet strength or size requirements.  Methods of how they further increase productivity through the substitution of in-process weld control monitoring in place of manual surface resistance checking, to automatically detect when a micro-ohms shift outside of the specification range occurs will be presented as well.  Also discussed will be how these manufacturers reduce labor and downtime associated with periodical machine inspections by taking advantage of a new clause in the MIL-SPEC that allows machine maintenance to only be performed when necessary.

Bio

As CEO of WeldComputer Corporation, Bob Cohen focuses on the development and commercialization of advanced monitoring and control techniques that continue to push the state of the art and quality assurance of the resistance welding process. His interest in resistance welding dates back to 1978 at General Electric's Corporate Research and Development Center, where he was involved in 2D axisymmetric transient thermal finite element modeling of the process. Bob was the inventor of the first commercially viable adaptive control, which was deployed in GE aircraft engine factories in the mid 1980's.  His work on the AWS C1 and D17 Committees was instrumental in updating the Recommend Practices for Resistance Welding and MIL-SPEC to recognize monitoring and adaptive control as accepted alternatives to destructive testing.