In the modern years, natural fibre composites have been converted into significant materials in many industries such as automotive, aerospace and and so on. Several types of natural fibre composites, particularly plant-based fibre composites, have been developed and tested. However, their mixed nature, engineer’s requirement of experience, an understanding of machinability databases, limit setting and trouble in manufacturing are barriers to extensive use of composites. The final shape of the natural fibre–reinforced composites (NFRCs) are obtained by conventional and unconventional machining. Machining of these composites generates confront due to the heterogeneous and anisotropic nature. Different methodologies and tools are intended to overcome the machining defects. In this article, a wide range of literature review on machining of NFRCs is examined with focus on conventional and unconventional machining operation. This article also discusses the influences of machining parameters and optimum conditions for machining of NFRCs.

Particle-filled polymer composites have become attractive because of their wide applications and low cost. Carbon fiber reinforced polymer (CFRP) is well known as a difficult-to-cut material, which has very strong physical and mechanical characteristics. Machining of carbon fiber reinforced composites is essential to have functional upshots, out of which drilling is the key operation needed for fabrication. In this paper Taguchi L₂₇ experimental design is coupled with grey relational analysis (GRA) to optimize the multiple performance characteristics in the drilling of fly ash-filled carbon fiber reinforced composites. Experiments were conducted on a vertical machining center, and Taguchi L₂₇ experimental design was chosen for the experiments. The drilling parameters, namely spindle speed, feed rate, drill diameter and wt% of fly ash, have been optimized based on the multiple performance characteristics including thrust force, surface roughness, and delamination. The GRA with multiple performance characteristics indicates that the wt% of fly ash and drill diameter are the most significant factors that affect the performance. Experimental results have shown that the performance in the drilling process can be improved effectively by using this approach.