An Investigation Into Non-Conventional Machining of Metal Matrix Composites

Introduction

It is through the employment of machining processes that the final shape of the product is achieved through the removal of unwanted material from the main workpiece (Pramanik et al., 2009). The mechanism of material removal in case of traditional machining process involves the removal in the form of chips owing to the plastic deformation resulting because of the force being exerted by the sharp cutting tools (Pramanik et al., 2013). The tool life in machining of metal matrix composites (MMCs) is shortened because of the abrasive nature of the reinforcements (Pramanik et al., 2006). The surface finish is also worse due to the tool-particle-machined surface interactions. The aforementioned limitations put hindrance to the use of MMCs (Pramanik et al., 2007). It becomes impossible for the conventional machining processes to machine MMCs with high percentage of reinforcing particles. Therefore, certain non conventional machining processes such as laser-beam, abrasive water jet, electro-discharge and electro-chemical have been developed for machining of such materials (Hihara et al., 2000). The last few decades have seen dominance of studies on traditional machining methods of MMCs over the non-traditional machining process such as electro-discharge machining (EDM), laser-beam, electro-chemical (ECM), abrasive water jet machining (AWJM) and photo-chemical machining (PCM). EDM process is one of the widely explored non-traditional machining process for particle reinforced metal matrix composites (PRMMCs) while PCM is the least explored of all. Thus it is obvious that a greater understanding is still required on machining of MMCs using non-traditional machining. A clear understanding of the different non-traditional methods used for machining of MMCs will aid in exploring the potential advantages of non-traditional methods over the traditional ones which then can then be applied in practical field. The present work therefore is an attempt to investigate the less explored non-traditional methods with focus on the mechanism of material removal, material removal rate, surface finish and the machining speed. The above parameters considered for the study will aid in assessing the recent developments, efficiency and the performance of the non-traditional methods. A better understanding on the mechanism of material removal rate leads to a proper visualization of the specific method and also the associated problems relating to the methods are revealed. The efficiency of machining process is reflected in its cutting speed which delineates the fact that how quickly the material removal takes place. The performance of a machining process is revealed by the level of surface finish and dimensional accuracy achieved. The performance of a machining process is considered worst if it gives rise to poor surface finish or poor dimensional accuracy. In the backdrop of the above discussion, the present work provides a brief overview of the non-traditional machining of MMCs by considering contributions from past researchers.

The rest of the chapter has been organized into: Laser beam machining, abrasive water jet machining, electro-chemical machining and electrochemical spark machining. The subsections in each of these sections describes in detail the material removal mechanism, major output response parameter and surface finish and dimensional accuracy for each of the aforementioned process. the chapter finally ends with the concluding remarks consisting of future directions.