This fully automated system produces a commercial heavy duty truck catalytic convertors. This welding system incorporates stainless steel MIG welding, press to force, and leak test operations. Weld cells are primarily rotary trunnion with robotic MIG welding, but table-top fixtures are also used. Strategically placed leak testing of sub-assemblies and mainline assemblies are incorporated to ensure gas tight requirements. Mainline material handling robots are used to transport the part from weld, to cooling, to testing, and also inspection stations. A manual assembly of covers and sensors finishes the unit before shipment to the OEM customer.