Ultra-precision machining of brittle materials - Material micro-structural perspective and cutting edge radius effect

Mechanical Engineering
Project type: 
Sponsored Projects
2019 - 2021
Principal Investigator: 
Dr. Afzaal Ahmed
Project Number: 
Sponsoring Agency: 
SERB - Start-up Research Grant (SRG)
Total Budget: 

Machining is the process of removing unwanted material from the blank to obtain the final product of desired shape, size and surface integrity. Most of the components goes through machining at some point during their production cycle. Machining of brittle materials such as glass, ceramics and tungsten carbide (WC) is often difficult because of their high tendency towards the characteristic brittle fracture. The most critical challenge in machining such brittle materials is to attain the material removal by plastic deformation rather than the brittle fracture. The promising technology used to machine these brittle materials is ductile-mode machining. In ductile-mode machining, the material is removed in the form of chip to generate a crack free finished surface. Ultra- precision machining (UPM) technology has been rapidly growing in emerging fields like biomedical, electro-mechanical and optical for producing miniature components with superior surface finish and dimensional accuracy. UPM is capable of machining components with tolerances less than 1 m and surface finish in nano-metric scale. During material removal at ultra-precision level, the undeformed chip thickness is in the order of few microns and might as well reach nano-levels. At this scale, factors like material microstructure, crystallographic anisotropy, subs-urface characteristics and cutting edge radius of the tool becomes highly significant. Therefore, much attention is needed to establish the fundamentals of machining at ultra-precision level considering the aforementioned effects for machining brittle materials. This project aims at performing the ductile-mode machining of brittle materials by ultra-precision orthogonal turning with and without laser heat assistance. The laser assisted machining is proposed to impart slight ductility to enhance the plastic deformation behaviour of brittle materials. Experimental investigations will be conducted to establish the underlying material removal mechanism for brittle materials in ultra-precision turning and the influence of machining parameters on the removal mechanism. In addition, a mathematical model to find the critical undeformed chip thickness for ductile-brittle transition. A significant contribution will be expected both in terms of theoretical and experimental research work to the current state of machining brittle materials at ultra-precision level.