Instead of cutting parts sequentially from left to right, use a randomized or spaced-out order. This allows one area of the sheet to cool down while the torch is working on a completely different section, minimizing localized thermal stress. Material-Specific Troubleshooting
Hot cracking occurs during the solidification phase of a weld or thermal cut. As the molten metal cools, it shrinks. If the surrounding material is too rigid or if the cooling rate is poorly managed, the internal tensile stresses exceed the strength of the nearly-solid metal, resulting in micro-fractures. In CNC operations, this is often exacerbated by: Excessive Heat Soak
: For small circles or delicate features where heat buildup is a risk, you can use SheetCam to insert "THC Off" codes. This prevents the torch from diving into the molten metal if the voltage fluctuates due to heat . How to Implement These Strategies sheetcam hot crack
Cracks may not appear immediately; they can develop anywhere from 48 hours to several weeks after the cut. CUMIC Steel Managing Cut Quality with SheetCam You can use SheetCam TNG
You can mitigate the risk of hot cracks by optimizing your G-code within SheetCam using the following features: 1. Optimize Lead-ins and Lead-outs Instead of cutting parts sequentially from left to
In CNC plasma and laser cutting, this most frequently happens at:
Slowing down the feed rate allows more heat to soak into the surrounding area, widening the heat-affected zone (HAZ) and reducing residual stress. In SheetCam, you can set specific rules to reduce feed rate by 50% As the molten metal cools, it shrinks
Remember: the goal is to get in, cut the metal, and get out before the heat has a chance to ruin the molecular integrity of your edge.
If the pierce delay in SheetCam is set longer than necessary, the torch sits stationary over the molten pool, transferring excessive thermal energy into the surrounding plate before the XY motion even begins.
Faster travel speeds generally reduce the total heat-affected zone (HAZ), cooling the metal more quickly and reducing the time grains have to pull apart during a vulnerable brittle phase.
If your hot cracks are occurring on sharp corners or small internal holes rather than the final closure point, the issue is likely due to machine deceleration. CNC machines must slow down to navigate sharp angles, which causes the plasma arc to burn wider and create a hot-crack appearance.