A hot crack is a structural defect that occurs during the solidification of metal. It typically happens when the supply of liquid metal is insufficient to fill the spaces between solidifying grains, which are being pulled apart by thermal shrinkage and tensile stress.
Cutting too slowly causes heat to bleed into the surrounding metal ahead of the torch. Ensure your feed rates match the manufacturer's charts for your specific plasma or laser power supply. Utilize Path Rules for Corners
SheetCam's Ramp Piercing capability solves this. Instead of piercing at a fixed height, the torch starts higher up, fires the arc, and begins moving forward while simultaneously descending to the cut height. sheetcam hot crack
He zoomed in on the "Cut Rules" tab. There it was: A 90-degree lead-in into a 1/4" hole meant the torch was plunging straight down, then dragging the arc sideways while the steel was still liquid. The arc force was literally tearing the puddle apart.
Key innovations
SheetCam is excellent at handling these thermal dynamics, but you have to know which settings to toggle. Here is your toolkit for preventing overheating.
He re-posted. Ran the cut on a scrap piece. A hot crack is a structural defect that
In SheetCam, adding a small (typically 1mm to 3mm, depending on material thickness) ensures that the metal is severed cleanly.
Create a custom in SheetCam to handle the end of the cut. For example, you can create a rule that triggers "Output Air/Gas Only" or reduces current right before the end of the toolpath. Alternatively, use a rule that accelerates the torch slightly as it approaches the lead-out to thin out the heat input. Material-Specific Considerations Ensure your feed rates match the manufacturer's charts
Use the SheetCam tool settings to set the lowest functional pierce delay for your material thickness, reducing heat accumulation at the start point. 3. Implement Proper Lead-Ins/Lead-Outs
