Analysis of the machining performance and surface integrity in laser milling of polycrystalline diamonds

The increasing use of diamond cutting tools necessitates the development of compatible fabrication technologies for the diamond tools, especially for three-dimensional surfaces with micron scale accuracy and good surface quality. In this article, the formation mechanism of surfaces milled using a nanosecond pulsed laser on polycrystalline diamond and the effect of process parameters on the milling performance such as material removal rate and surface integrity are investigated based on a statistically designed experiment. It is shown that laser milling is a viable technology for three-dimensional processing of polycrystalline diamonds with good machining rates and acceptable surface quality. A microscopy analysis indicates that diamond graphitization can occur on the milled surfaces, and laser pulse energy and pulse overlap have a significant effect on the milled surface morphology. Characterization of the machined surface/subsurface is conducted using Raman spectroscopy, and the relationships between damaged surface layer thickness and process parameters are discussed. It is found that an optimum pulse overlap together with moderate pulse energy may be used, while the scan overlap should be selected in the vicinity of its optimum value at around 50% for a good surface quality while maintaining a high material removal rate.