Arc welding is one of the most common applications in general use today. The principle employed is to replace a welder with a welding cell. On this basis a loader can run more than one welding cell, thereby de-skilling the manual content of production. That is not to take the welding knowledge out of the process, but to embed it in the robot's capabilities. The welding skills are still required during setup and product changover, but only at that time. The requirement is for a welder/programmer to set up and an operator to load and initiate the production cycle.

This requires the robot cell to be configured for manual loading, or fit up, of the parts to be permamently assembled by the process. The cell will comprise a six axis robot, an intelligent weld set, a solid wall enclosure/UV protective curtains, fume extraction and some nozzle cleaning anti-spatter equipment. Everything else in the cell is about the work envelope and the size of product being processed.

The operator has to load the part in safety. To achieve this, it may be possible to load a jig outside the enclosure and slide it into the cell/robot envelope for processing. When complete, pull it out, unload and reload, and repeat the process. This builds in robot downtime when the part is unloaded and reloaded. The next step would be to have two load positions. This will enable one part to be unloaded and reloaded while the robot provcesses the other part. A twin end changer can provide 2 load stations and motorise the switchover. Time is lost during the 180° index.

The motorised end changer can also incorporate a rotary tables or even rotate and tilt tables. These additional axes may be point to point or fully integrated robot axes. The robot may also be running on a floor mounted linear track or the track may be inverted overhead. Another technique is to invert the robot on a jib structure to run above an end changer. All these techniques will determine the potential welding envelope.

Investment in the cell is a trade off between cost and flexibility. It is neccessary to decide whether the robot will move around the part (ie. to weld a farm gate, signal gantry or earth moving equipment), or to move a much smaller part around within a static robot's work envelope.

In a jobbing shop the welding cell would need greater flexibility to accommodate a variety of parts, some of them unknown at the time of purchase. A simple cell will limit the type of work that it can do.

In a high production environment the welding cell is likely to be welding the same parts or variants of the same parts in high volumes, and hence provide a more cost effective solution. (lower tooling costs and high volume shift patterns)

There is also a place for the dedicated welding machine for medium volume low cost solutions. (rotary table and weldset for pipe flanges etc.)

A jobbing shop running small batches will have a high on cost for tooling up and a high tooling redundancy rate. It is helpful if tooling design and manufacture can be provided 'in house'.

The arc welding market is the largest provider of homes for remanufactured robots and systems. There is a thriving trade in the secondary market here, after all, it's only like employing more welders when a new contract comes in.

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