Effect of workpiece vibration on drilling of GFRP laminates

Effect of workpiece vibration on drilling of glass/epoxy (GFRP) laminates using three types of drill, e.g. tipped WC, 2-flute solid carbide and 3-flute solid carbide has been studied. A UD-GFRP laminate of 4 mm thickness was prepared and drilling was carried out using a vertical drilling machine. First, an optimum speed, feed and frequency combination for which thrust, power and tool wear are minimum was arrived at by drilling the specimen using varying speed, feed and frequency. The thrust force was measured using strain-gauge type dynamometer. Tool wear (flank wear) was measured using a Tool Maker’s microscope. The workpiece was subjected to vibration using a variable frequency generator close to the hole being drilled. Frequency used was 220 Hz and amplitude of vibration was 10–15 μm. Thrust, tool wear, temperature, power and AE (RMS value) were measured. It was observed that by vibrating the workpiece during drilling all these five parameters are very much reduced. Also, among the three types of drills performance of 3-flute solid carbide was found to be the best.