CMT Welding Quality Control System

This paper describes system that was developed for measurement of voltage and current during welding with CMT (ColdMetalTransfer) welding robot. System should assist welding machine operator with inspection of products. Main objective was to record welding signal, separate individual joints, normalize signal, and compare it with reference signal from database. Result of analysis should be detection of faulty or missing joints right on the site. System consists of data acquisition unit with two ADC (analog to digital converter) channels, protective and scaling circuits, operator software for analysis and database software for storage data and configuration in database. During development, method of joint separation was changed many times, growing database was changed to SQL (Structured Query Language) database with separate software and we found that because of differences between individual welders and joints, auto-scaling of input is necessary.