| Thermal gradients established in workpiece during cutting. | The plasma cutting processes uses a high temperature plasma arc to melt and cut through the workpiece. As a result, the workpiece will heat up locally which can establish a thermal gradient in the part. This gradient can lead to distortion which will effectively warp you workpiece. Typically with material that is 3/16" and thicker, distortion is not as much of an issue because the plate is strong enough to resist this warping. On thinner plate and sheet metal, distortion can be an issue which can make detailed cutting impossible without distorting the workpiece. Fortunately, some cooling methods can be used that completely eliminates this distortion when cutting. A water table is simply a tray filled with water that surrounds the slat bed of a gantry-style CNC plasma machine. The tray is filled with water to below the top surface of the slat bed so that the action of plasma cutting causes water in the tray to splash back up onto the backside of the part being cut. This allows for part cooling, reduces cutting noise, decreases part warpage, reduces arc flash, and reduces smoke and cutting dust. A water table can be purchased for the CrossFireTM machine from Langmuir Systems or it can be made by following our guide in the Projects page. If you are not able to purchase a water table, we have had an equal amount of success by using a standard spray water bottle and continuously spraying the plasma arc with the water bottle during cutting to cool the part. |