Laser-Assisted Machining of Ti-6Al-4V Fabricated by DED Additive Manufacturing

Recently, the commercialization of hybrid machine tools that combine directed energy deposition (DED) additive manufacturing (AM) technology and subtractive manufacturing (SM) has rapidly progressed. This technology trend has been developed to meet the market demand for processing quality (precision) and productivity, and to produce products such as lightweight parts, and complex and special functional parts, as well as to facilitate mold production and part repair. Compared to SM technology, metal AM technology has limitations in terms of surface quality and shape accuracy. Therefore, post-processing is necessary for the AM output. Laser-assisted machining (LAM) is an innovative hybrid technique in which surface quality and productivity can be improved by enhancing the machinability of difficult-to-cut materials. LAM studies have mainly been performed on titanium alloys, nickel based alloys and ceramic materials. However, except for ceramics, no high-strength material studies have been conducted to analyze the LAM process machining characteristics of workpieces fabricated by AM process. Therefore, in this study, LAM is applied to post-processing of output fabricated by AM of Ti-6Al-4V. DED device was developed using metal powder feeder and a laser. The Ti-6Al-4V workpieces were successfully fabricated through many tests. The cutting depth for LAM was selected through thermal analysis for LAM of the fabricated workpiece. Compared to the case of traditional machining without preheating, machining characteristics in LAM experiments were analyzed and property testing was performed.