Surface Roughness and Morphology Studies on Machining Hybrid Composite Material Using Abrasive Water Jet Cutting Process

Abstract

The accelerated demands of engineered products with superior properties have inspired researchers to investigate the substitutes of the manmade fibre-based composites and explore the utilization of natural fibre based polymer matrix composites (PMC). Although manmade fibres have many benefits, but their decreasing usage in decade has been due to high primary cost, non-bio degradability, non-renewability, high energy ingestion in engineering process and unfavourable eco-friendly effects. Bio fibres still compensate for their deprived compatibility with the matrix, naturally high moisture absorption rate with their positive aspects like low cost, nonabrasive nature, low density, good thermal characterise, superior energy recovery and bio degradability. Hemp is an important fibre used for manufacture a variety of automobile parts, rope, yarn, household application etc. Therefore, researchers are investigating new zones for utilization of hemp fiber as in reinforcement polymer matrix composite (PMC). Kevlar fibre is used for hybridization purpose. NaOH treatment is used for improve the adhesion strength between the matrix and hemp fibre. The natural filler (palm and coconut shell powder 75–150 µ) materials are being added to increase the mechanical interlocking property and also the bonding strength between matrix and fibre. In this research, the hybrid natural fibre composite was developed by Hemp/Kevlar/filler. Four types of specimens were developed in various different combinations (i.e. 0, 5, 7.5, and 10%) of filler. The size of the filler material and fibre was measured using scanning electron microscope. The trimming (machining) of the composite is very challenging to attempt using conventional machining processes. Therefore, non-traditional machining process i.e. abrasive water jet cutting was attempted. For trimming (machining) of polymer composites, Abrasive Water Jet Machining (AWJM) is widely employed in manufacturing industries. In the current research, kerf tapper, surface roughness (Ra) and the material removal rate (MRR) were examined under the influence of input factors such as Jet Pressure, nozzle Speed and Stand of Distance (SOD). Taguchi L9 orthogonal array based experimental study conducted. From the analysis, the nozzle speed was found the most significant factor. But, the jet pressure was always influenced by kerf wall inclination. The SEM image has been shown fibre pull out, filler distribution in a matrix and helps to understand the surface morphology of the fractured surface during trimming (machining).