CNC Plasma Cutting Operations
CNC plasma cutting tables use a computer-controlled gantry system to move a plasma torch precisely over a cutting table, cutting complex profiles from flat steel plate based on DXF (Drawing Exchange Format) or other CAD file inputs. Plasma cutting uses an electrically conductive ionized gas (plasma) at 20,000–50,000°F to melt and blow through the workpiece — far faster and more economical than oxyfuel cutting on most plate thicknesses, with superior edge quality for CNC applications. Setup procedure for CNC plasma: 1) Nest the DXF part files using nesting software (SigmaNEST, ProNest, or similar) to arrange parts on the sheet with minimum material waste. Typical nesting efficiency for complex parts: 70–85% material utilization. 2) Set pierce parameters in the CNC controller: pierce height (the torch height for initial material penetration, typically 2× the cut height), lead-in distance (the path from the pierce point to the cut profile, ensuring the pierce kerf is outside the finished part), and lead-out. 3) Set cut height, amperage, and cut speed based on material type and thickness. A Hypertherm 85A plasma at 65A cuts 1/4" mild steel at approximately 100 IPM with a kerf of approximately 0.070". 4) Set the material down on the cutting table (water table or dry cutting table), index the home position, and run the cut. Post-cut operations: plasma-cut edges typically have a slight bevel (the cutting arc produces a slightly angled edge) and dross (solidified slag) on the bottom edge that must be removed. For weld preparation, plasma edges used as groove faces typically require grinding to remove the hardened plasma-cut edge layer and the dross, achieving the clean fusion surface required for quality welds.