Robotic Welding Basics
ABICOR Binzel Posted 12/01/1999
What welding tasks are suitable for automation? The short answer is repetitive tasks on similar pieces.
Obviously, the number of items of any one type to be welded must be continually high enough to justify automating the process. If the joints to be welded on a workpiece are few, straight, and easily accessible, a rack-mounted, automatic gas metal arc welding (GMAW) gun or gas tungsten arc welding (GTAW) torch may be suitable for the key welds.
An automatic gun also can be used in a fixed position or on a curved track for a curved or circular weld, such as joining two pieces of pipe or welding a flat base to a cylindrical shape - - a task in which a workpiece can be rotated past the gun.
If parts normally need adjustment to fit together correctly, or if joints to be welded are too wide or in different positions from piece to piece, automating the procedure will be difficult or impossible.
The tabletop-size robot is used to maximum effect - - welding a workpiece in one side of a revolving jig. Each side of the jig also can be revolved to allow access to both sides of the workpiece.
Robots work well for repetitive tasks on similar pieces that involve welds in more than one axis or where access to the pieces is difficult. Welding robots are used in two ways in manufacturing -- as elements in a production line and as stand-alone units for batch production. Few companies move from all manual welding to a completely automated production line, so many people introduce robotic welding with a stand-alone cell.
At fabrication or welding tradeshows, a variety of welding robots can be seen performing complex maneuvers and elegant pirouettes similar to a troupe of ballet dancers. These displays are designed to demonstrate the speed and flexibility of today's generation of robots. The fact is, dance moves aside, today's robots can handle a wide range of welding applications.
When choosing a robot, a fabricator should consider the reach and payload of the arm, speed and performance limitations, service, and price. The major manufacturers offer robotic arms for welding in three size ranges: a table-top size with a 6-pound (3-kilogram) payload, medium-sized machines with a 13.2-pound (6-kilogram) payload, and larger models with a 22.2-pound (10-kilogram) payload.
The medium-sized and larger robots have reaches in the 5- to 6-foot range. Payload determines the size and weight of the welding torches, cable assemblies, and torch mounts that can be carried by the robot arm. The size of the items to be welded determines the robot reach required.
ABICOR Binzel, 650 Medimmune Ct., Suite 110, Frederick, Maryland 21703, phone 301-846-4196, fax 301-846-4497. ABICOR Binzel is a manufacturer of semi-automatic, automatic, and robotic GMAW guns, GTAW torches, and robotic peripheral equipment.
Reprinted with permission from the November/December 1999 issue of Practical Welding Today®, copyright 1999 by The Croyden Group, Ltd., Rockford, IL, www.fmametalfab.org.