Reutilization of a reflected laser beam as an effective approach for machining metallic materials with low laser absorptivity.

Laser micromachining technology is a method of precision manufacturing that is experiencing growth with wide applications. Due to the increasingly tense energy situation, it is an appropriate time to consider the efficiency and economic issues of growth in precision manufacturing. The reutilization of a reflected laser beam (RRLB) for modifying metallic materials with low laser absorption is proposed in this article to reduce the energy and time consumption of the laser micromachining process. The novel laser machining approach, using an RRLB, which combined a nanosecond laser with an RRLB optical system of fiber laser, was applied on 6061 aluminum to validate its superior characteristics. The characteristics of the RRLB were clarified by the experiment on 6061 aluminum. Compared with normal laser machining (NLM), the processing efficiency of the RRLB can be greatly improved. Owing to the reutilization of the reflected laser beam energy without a thermal relaxation time, a higher-intensity laser-metal interaction can be realized for the RRLB; thus, the incoming energy can be utilized more effectively by ablating more material instead of diffusing it into the sample. Moreover, practical examples by using the RRLB, such as surface darkening on 6061 aluminum, surface polishing on additive manufactured Al alloy, and surface colorization on titanium and stainless steel, also demonstrated the excellent versatility and superiority of the RRLB approach.