Laser-induced plasma micro deburring: Time-resolved observation and workpiece characterization

Micro deburring (i.e., removing microscale burrs from microscale workpiece features) is often challenging. A previous paper reported preliminary research on laser-induced plasma deburring (LPD), a novel process utilizing laser-induced plasma to remove burrs, which shows that LPD can potentially avoid or greatly reduce the drawbacks of many current deburring methods. An ideal deburring technology should leave no or small residual effects on the workpiece except burr removal. However, the residual effects induced by LPD on workpieces have not been well studied. This paper reports experimental work on LPD of a micro-channel on an aluminum alloy workpiece, with the emphasis on studying LPD-induced residual effects on the workpiece. In the LPD processes investigated, plasma is induced by laser ablation of a graphite, copper or titanium sacrifice plate (not a portion of the workpiece) in the air or argon environment. Under the studied conditions, the LPD using all three types of sacrifice plates can effectively remove most of the targeted burrs on the workpiece. On the other hand, it has been found that LPD using laser-induced plasma from the graphite sacrifice plate in air produces the smallest residual effect. The LPD process induces no or a very small change in the surface elemental composition, roughness, hardness and grain size of the micro-channel sidewall on the aluminum workpiece. The related fundamental mechanisms have been analyzed.