A study of micro-channel size and spatter dispersion for laser beam micro-milling

During micromachining the accuracy of micro-feature is always a major concern. Using laser beam micro-milling (LBMM) the produced size is generally larger than the input design size. Another important drawback of LBMM is the formation of melt spatter around the feature geometry. The spatter adheres within the premises of the machined feature and influences the machining results, especially the geometry of previously machined features by adhering inside or around the feature. Determination of spatter size is very important when the objective is to produce an array of micro-features such as micro-channels. Thus, the minimum distance between two consecutive micro-features is necessary to be known in order to achieve safe geometry for which the size of spatter plays a significant role. The knowledge of spatter scattering and pre-calculated distance of dispersing spatter could certainly assist the machinist in estimating the safe distance between adjacent micro-channels. In this study, the micro-channel size and average spatter size are studied during the micro-milling of Ti-6AL-4V by Nd:YAG laser beam machining (LBM). Response surface methodology (RSM) has been utilized to plan a set of experiments and mathematical models are proposed to pre-calculate the channel size and spatter dispersion. Finally, the models are validated through confirmatory tests showing an acceptable range of error.