Great machinists know the need for proper fixturing. And they also know the fixturing has to be true to the machine tool motion. I don’t pretend to be a great machinist, but I know quite a few, including Curtis Waffle pictured below in an old photograph. Curtis is a master machinist with 35 years at Flow. The large bed of a typical waterjet machine is an XY plane, and that plane must match that of the machine. If the worktable is not flat to the machine motion it creates ongoing headaches and part accuracy and quality issues for the operator.
Everyone who cuts parts out of raw stock or a work-piece knows you can’t cut a good part if it isn’t sufficiently held in place. So, what do we have to consider when we’re talking about waterjet cutting? The good news is a waterjet cuts with low force. Where a milling machine might force a rigid cutting tool into a material at 10, 100, 300 pounds of force (4.5, 45, 136 kg), the waterjet head doesn’t touch the part — just the supersonic stream that exits the head touches the part.The machine can’t tell if the jet is cutting material or just shooting into nothingness. The part, however, does feel low forces during cutting.
Although the picture is of pure waterjet cutting pizza, I’m going to focus on abrasive waterjet cutting applications in this post. Fixturing requirements are different in pure waterjet cutting, partially because the material is often very light and the jet forces are an order of magnitude (10x) lower compared to abrasive waterjet.