Executive Summary : | Ductile mode machining is used to process hard and brittle materials to enhance surface integrity as the component’s performance is directly related to the surface and sub-surface features. But, the changes induced by ultra hard ceramics (UHC) machining are very critical due to safety and sustainability concerns. In this aspect, ductile mode machining is not well established in UHC materials whose hardness is greater than 2100 VHN such as Al₂O₃, SiC, WC, B₄C, etc. With their extensive properties, the surface generation with ultimate structural integrity i.e. mirror finish is in great demand for space, military and electronics applications. However, the surface generation in the bare surface of UHC materials does not meet the machinability and surface finish as per the requirements through conventional machining due to its less dense and fracture toughness. Also, the current practices involved random material removal and are limited to fully dense and applications. Therefore, ductile mode machining by single point diamond turning (SPDT) was approached for processing ceramics. However, due to the higher hardness, brittleness and microstructure defects of UHC, the phase transition, surface form and finish were limited. In addition to this, the occurrence of grain dislodgement and fracture causes higher tool wear and lower yield. To enhance the ductile regime during machining UHC, micro laser assisted machining (µ-LAM) with SPDT technique can be proposed in this work in which SiC can be taken as a target material to prove the machinability of the proposed technique. This ultraprecision machining at a nanometric cutting scale can produce crack-free surfaces & reduced tool wear, and also achieve a high precision surface & a surface finish of a few nanometres. However, the studies i.e., machinability, and development i.e., surface generation are still scarce on UHC like SiC due to the lack of clarity on the combined effect of pressure and temperature over material removal. At this effect, the laser power, tool geometry and materials microstructure are highly substantial for improving ductile regime cutting. Therefore, much attention is required to establish fundamental research on the combined effect of pressure and temperature on material removal mechanisms and structural phase transformations of SiC with different microstructures. Based on this, the high precision surface can be generated without significant defects by using the µ-LAM with SPDT. Therefore, PI will examine the insights of ductile mode machining and demonstrate the achievable surface finish on SiC by using µ-LAM with SPDT for the purpose of producing surface generation for wide optical applications. For this study, advanced characterization tools will be used to investigate the material removal, phase transition, chip thickness, tool wear and surface. And, the optimization can also be done for the enhancement of surface features and machinability. |