If you have optimized your SheetCam G-code and hot cracking still occurs, look to these physical variables on your shop floor: Impact on Hot Cracking
When a plasma arc or laser beam passes through a metal sheet: The immediate cutting edge reaches melting temperatures.
When you cut an interior hole, the heat has nowhere to go; it's trapped on the inside. As the interior cools, it tries to pull the outer shape with it. If you cut the part free from the sheet first, the part is no longer mechanically restrained, so the interior cuts will not be able to pull or distort the material as severely. sheetcam hot crack
SheetCam does not physically cut the metal, but its instructions dictate the speed, path, and duration of heat exposure. Errors in your SheetCam tooling or operation setups can severely exacerbate thermal stresses. 1. Poorly Configured Lead-Ins and Lead-Outs
Open your Jet Cutting Operation in SheetCam. Locate the Overcut box and enter a value. For thin materials (14 gauge to 1/8"), an overcut of 0.030" to 0.050" (0.75mm to 1.2mm) is usually sufficient. For thicker plate metal, increase this to 0.100" (2.5mm) . 2. Optimize Lead-Outs If you have optimized your SheetCam G-code and
Dropping the feed rate to 60–80% for the last 5mm of the cut allows the arc to stabilize and the "trail" of the plasma flame to catch up to the torch head, ensuring a cleaner severance. 2. The "Overcut" Technique Under your Jet Operation settings: Overcut: Set this to 2mm–5mm.
I can provide specific adjustments to help reduce the heat-affected zone. How to Install, Setup & Configure SheetCam For Avid CNC If you cut the part free from the
Plasma cutting is an incredibly efficient method for slicing through metal, but it comes with a formidable challenge: heat. When you run a super-heated plasma arc over a steel plate, the intense thermal energy doesn't just cut—it warps, stresses, and sometimes even cracks the material. In the world of CNC plasma fabrication, "hot crack" and "thermal distortion" are the persistent enemies of precision. This comprehensive article explores the primary causes of this issue and, more importantly, how to leverage the powerful features within software to control heat, optimize cut sequences, and produce crack-free, perfectly flat parts.
If you are cutting parts that drop out of the sheet (freeing themselves), they lose structural support. Cracks form as they fall.
Using a curved exit rather than a straight stop keeps the plasma stream moving away from the finished edge as it shuts down, moving the "crater" into the scrap material rather than the part. Professional Tips for Thick Plate