Burr and dross form when assist gas does not fully expel molten metal; taper results from changes in focus, energy density and gas flow through thickness. Power, speed, focus, nozzle standoff/coaxiality, gas purity/pressure, surface condition and material lot interact.
Values in this article support engineering screening during design review, RFQ and prototyping. They do not replace formal calculations, material data sheets, qualified procedures or contractual standards.
READ THE DEFECT FIRST
- Fine hard burr at the bottom: often excessive speed, insufficient energy or incorrect focus. - Large removable dross: possibly low speed, excessive heat or unstable melt ejection. - Dross on one side: first inspect nozzle damage, beam/nozzle misalignment, optic contamination and sheet warp. - Burned/non-round small holes: hole diameter near sheet thickness, excessive piercing energy or poor lead-in; drill critical small holes later.
BUILD A PROCESS WINDOW
Do not tune only by eye. Run a small DOE on one material lot: low/medium/high speed and negative/zero/positive focus while holding other parameters; record kerf, top/bottom dimensions, burr height and roughness. Then optimize gas pressure and nozzle. Retain an approved parameter set and first-off images for each material-thickness-gas combination. Define a maximum burr where needed—e.g., 0.1 mm on an assembly edge—and specify edge break for handling safety, not just “deburr.”
PROJECT CHECKLIST
Material/thickness; gas and purity; nozzle/coaxiality; focus; speed; pierce strategy; small-hole ratio; burr/cut acceptance; subsequent bend direction.