This paper presents the feasibility study of potential application of recently developed surface defect machining (SDM) method in the fabrication of silicon and similar hard and brittle materials using smooth particle hydrodynamics (SPH) simulation approach. Simulation study of inverse parametric analysis was carried out to determine the DruckerPrager (DP) constitutive model parameters of silicon by analysing the deformed material response behaviour using various DP model parameters. Indentation test simulations were carried out to perform inverse parametric study. SPH approach was exploited to machine silicon using conventional and surface defect machining method. To this end, we delve into opportunities of exploiting SDM through optimised machining quality, reduced machining time and lowering cost. The results of the conventional simulation were compared with the results of experimental diamond turning of silicon. In the SPH simulations, various types of surface defects were introduced on the workpiece prior to machining. Surface defects were equally distributed on the top face of the workpiece. The simulation study encompasses the investigation of chip formation, resultant machining forces, stresses and hydrostatic pressure with and without SDM. The study reveals the SDM process is an effective technique to manufacture hard and brittle materials as well as facilitate increased tool life. The study also divulges the importance of SPH evading the mesh distortion problem and offer natural chip formation during machining of hard and brittle materials.

Single point diamond turning (SPDT) of large functional surfaces on silicon remains a challenge owing to severe diamond tool wear. Recently, tremendous efforts have been made in understanding the machining mechanics, especially wear mechanism of diamond tools in SPDT of silicon. However, the localized transition of machining mode from ductile to brittle as a result of progressive tool wear has not been well understood yet. In this paper both experimental and numerical simulation studies of SPDT were performed in an effort to reveal the underlying phenomenon of ductile to brittle transition (DBT) as a consequence of diamond tool wear. Series of facing and plunging cuts were performed and the profile of machined surface was evaluated together with the progression of tool wear. The transition stages from ductile to brittle were identified by analysing the surface profiles of plunging cuts using a scanning electron microscope (SEM) and a 2D contact profilometer and a white light interferometer. The progressive degradation of the cutting edge of diamond tool and its wear mechanism was determined using Least Square (LS) arc analysis and SEM. The study reveals that at initial tool wear stage, the ductile to brittle transition initiates with the formation of lateral cracks which are transformed into brittle pitting damage with further tool edge degradation. Numerical simulation investigation using smoothed particle hydrodynamics (SPH) was also conducted in this paper in order to gain further insight of variation of stress on the cutting edge due to tool wear and its influence on brittle to ductile transition. A significant variation in frictional resistance to shear deformation as well as position shift of the maximum stress values was observed for the worn tools. The magnitude and distribution of hydrostatic stress were also found to change significantly along the cutting edge of new and worn diamond tool