SheetCam does not physically cut the metal, but it dictates exactly how the heat source interacts with it. Improper lead-ins, incorrect feed rates, and poor path planning in SheetCam can cause the torch to linger, overheat, or stress vulnerable areas of the part.
An overcut tells the torch to continue moving past the starting point of the cut loop before shutting off.
SheetCam provides several powerful parameters to control how heat is distributed across your material. Use these software fixes to eliminate hot cracking. Optimize Lead-Ins and Lead-Outs
A hot crack is a small fracture that develops as the molten metal pool rapidly cools and solidifies at the end of a cut. sheetcam hot crack
If your SheetCam toolpath commands the torch to stop moving at the exact same time it commands the torch to turn off, the torch will dwell in place while the arc fades. This injects excess heat into a stationary point, creating a larger molten pool and a higher risk of hot cracking.
While SheetCam itself does not physically melt metal or cause thermal fracturing, the CAD/CAM settings you configure within SheetCam directly dictate the torch path, dwell times, and gas transitions. If these settings are misconfigured, they create the exact thermal and mechanical conditions required for hot cracking to occur.
He overrode the safety. Manually set the cut speed for the hole to 60% of the main speed. Added a 0.2 second "dwell" at the pierce to let the arc stabilize. Then he added a —a dummy move where the torch would jump to an offcut, fire for 0.1 seconds, and dump the thermal load before cutting the next feature. SheetCam does not physically cut the metal, but
Implement Path Rules in SheetCam to slow the torch down or shut the air/plasma off a fraction of a second early (the "End of Cut" rule).
What are your current and pierce delay times in SheetCam?
If you still get a small crater even with an overcut, your plasma arc might be staying on too long after the motion stops. This is controlled by your post processor. SheetCam provides several powerful parameters to control how
to configure "Path Rules" and tool settings that mitigate the thermal stresses leading to cracks and poor edge quality: Reduce Cutting Speed:
When setting up your operation, ensure your toolpath is configured to cut all internal contours (holes and slots) before tackling the external profile. While SheetCam's thermal distortion mode generally handles this well, you may need to manually adjust if you are working with extremely thin gauge metals or very detailed parts. Sometimes, breaking the operation into separate layers (one for holes, one for the outline) gives you ultimate control over this sequence.
Essentially, your toolpath is "cracking" the integrity of the part because the physics of the cut weren't accounted for in the CAM software.
When a torch finishes a closed loop (like a circle), it often leaves a small "divot" or a localized hot spot where the start and end meet. This is a prime location for a crack to propagate.