The monitoring of any manufacturing process is essential for achieving the “six sigma” goals of production quality. Often the cost of monitoring equipment is significantly less expensive than the cost ramifications of the field failure of a single weld. Destructive testing methods include tensile pull-test, peel tests, shear tests, corrosion tests, optical microscopy, cross-section inspection, and scanning electron microscopy. These tests are typically used to qualify processes initially as well as periodically. On-line monitoring of key resistance welding parameters is a more effective method of continuous weld quality.