Understanding the relationship between your SheetCam toolpath parameters and the metallurgy of plasma cutting is essential for producing clean, structurally sound parts. What is a Hot Crack?
SheetCam features a powerful system. You should create a rule that triggers when approaching tight corners or small radii.
Improperly configured CAM strategies can lead to localized overheating, rapid quenching, and excessive mechanical stress—the exact ingredients required for hot cracking. This article explores the root causes of hot cracking in thermal cutting, how SheetCam settings impact this phenomenon, and actionable strategies to eliminate the defect from your production line. What is Hot Cracking in Thermal Cutting? sheetcam hot crack
The finish of a cut is almost entirely dictated by the lead-in and lead-out strategy. A straight line plunge often leaves a noticeable divot or "dross nipple" because the arc takes a second to stabilize and turn off.
Use SheetCam to create longer, curved lead-ins . This allows the pierce (the hottest part of the process) to happen further away from the finished edge. You should create a rule that triggers when
If you notice microscopic hairline cracks or visible fractures along your cut edges, systematically check the following parameters: Potential Cause SheetCam / Machine Fix Cracks initiating at the pierce point Severe thermal shock from direct pierce Switch to an with a longer radius. Cracks at the final corner of the part Heat accumulation from torch deceleration
You can edit your specific post processor in SheetCam to include a brief pause or to command the torch off slightly before the motion stops. Alternatively, check your CNC control software (like Mach3, Mach4, or FireControl) for settings related to Torch Off Delay and ensure it is set to 0 seconds so the software doesn't force an artificial dwell at the end of the cut. Recommended SheetCam Settings Quick-Reference Material Thickness Recommended Overcut Lead-Out Type Lead-Out Length Thin (under 1/8" / 3mm) 0.040" (1.0mm) 0.050" (1.2mm) Medium (1/8" to 1/4") 0.080" (2.0mm) Arc or Line 0.080" (2.0mm) Thick (Over 1/4" / 6mm) 0.120" (3.0mm) 0.120" (3.0mm) Conclusion What is Hot Cracking in Thermal Cutting
In SheetCam, apply a (an arc or line away from the part scrap).
If you have optimized your SheetCam settings and are still experiencing hot cracking, the issue may stem from your physical setup: