Workpiece fixation and positioning

In order to join parts successfully in a robotic welding application, individual parts must be aligned precisely and held securely in place while the welding is proceeding. An important consideration, then, is the design of a fixture which holds the individual parts in the proper alignment. The tool must allow for quick and easy loading, it must hold the parts in place securely until they are welded together and must allow the welding gun unrestricted access to each weld point. 

One starting point for positioning the workpiece for robotic welding may be the fixture already used for manual welding even though specialized positioners are used to improve the versatility and to extend the range of robotic arc welding systems. The usable portion of a robot work envelope can be limited becuse the welding torch mounting method does not allow the torch to reach the joint properly. Special positioners eliminate some of these limitations by making the workpiece more accessible to the robot welding torch. 

The positioners used with robots also have to be more accurate than required for manual or semiautomatic welding. In addition the robot positioner controls must be compatible and controllable by the robot controller in order to have simultaneous coordinated motion of several axes while welding.

However, loading and unloading stationary jigs of the robot cell can be time consuming and impractical. It is often more efficient to have two or more fixtures on a revolving workpiece positioner, despite a higher initial cost. With a revolving table for instance,  the operator can load and unload while the robot is welding. Obviously, this speeds up the process and keeps the robot welding as much of the time as possible.