Drillability study of pultruded and sheet moulding compound thick polymeric composites

Abstract

This article discusses the effects of process parameters (feed and spindle speed) on quality characteristics (thrust force, torque, surface roughness and ovality) for standard and special geometric design of a drill body in dry drilling of pultruded and sheet moulding compound thick composites. Pultruded (non-laminated) and sheet moulding compound (laminated) thick glass fibre–reinforced plastic composites with a higher percentage of fibre weight fraction are extensively used in construction of bridges, prefabricated platforms, ballistic applications, structural applications, instrument bases and automotive load floors, and therefore, prediction of better performance drill helps the fabrication industry in making good quality holes. The drilling experiments using coated tungsten carbide drills, twist drill (standard geometry) and ratio drill (special geometry) of diameter of 10 mm were conducted using response surface methodology. Analysis of variance of the experimental results reveals that for both twist drill and ratio drill, feed is more significant in influencing the quality characteristics. The experimental values obtained for quality characteristics are empirically related to process parameters by developing response surface models using Design-Expert software. Analysis of the experimental results reveals that ratio drill performs better in pultruded composites and twist drill performs better in sheet moulding compound composites. The optimal process parameter levels within the selected range for minimizing all the quality characteristics together were determined.