Office of Technology Transfer – University of Michigan

Online Monitoring System and Method for a Short-Circuiting Gas Metal Welding Process

Technology #2426

Questions about this technology? Ask a Technology Manager

Download Printable PDF

Shixin Jack Hu
Managed By
Keith Hughes
Assistant Director, Physical Sciences & Engineering 734-764-9429
Patent Protection
US Patent Pending


Gas metal arc welding (hereinafter “GMAW”) of automotive thin sheets involves the use of low currents, preferably less than 150 amps, for causing transfer of metal to occur when the welding apparatus is in a short-circuiting mode. GMAW is commonly operated in automatic or semiautomatic modes and utilized in high production welding operations. However, the practice of short-circuiting GMAW to consistently produce high quality welds is regarded generally as quite difficult due to a resulting intermittent welding arc and short-circuiting metal transfer.

Existing methods for inspecting the quality of welds include, for example, trial and error, visual inspection, destructive testing, and arc sensing. Current industry methods of monitoring welding processes and weld quality are thus heavily dependent on the knowledge, sensory perception and experience of welders, which render the methods labor-intensive, subjective and frequently inefficient. They also tend to involve analysis that occurs after the weld has been made; and do not allow for an early opportunity to scrap a part or take remedial measures to fix the weld.

It would be desirable to be able to continuously monitor weld stability, quality or geometry during a welding process, in real-time. It would be especially desirable to have a system that, based upon feedback from the monitoring, could adjust one or more welding process parameters for improving weld stability, quality or geometry (e.g., the weld length, the sample rate frequency, the short-circuiting current, the arc current, the short-circuiting voltage, the arc voltage, or otherwise).


A reconfigurable optical method and system for rapidly measuring relative angular alignment of flat surfaces are provided. The method and system can be used to rapidly and simultaneously measure the relative angular alignment of machined flat surfaces of a manufactured part. The system can measure parallelism, perpendicularity or angular alignment of multiple flat surfaces. The system can also be used to set up a range of reference angles to which machined surfaces can be compared.