A welding clamp system using a fixture plate with a bulkhead that allows the clamp system to be coupled to a robotic arm. The robotic arm supplies air and electricity through pneumatic and electrical ports, enabling operation of the clamp system. The air is routed to pneumatic cylinders, which power a pneumatic clamp mechanism that moves sliding clamp fixtures along tracks. The sliding clamp fixtures press a work piece against immobile clamp fixtures, allowing a work piece to be secured and held during welding. Presence of a work piece is detected by proximity sensors which are mounted into the fixture. The clamp system allows a robotic arm to grab a work piece from a supply area, initiate and complete welding of the work piece, and then release the work piece onto a discharge station for removal of the completed work piece.