Drilling of Glass Filled Resin Bonded Materials

Abstract

[Master of Philosophy thesis]. Glass Reinforced Plastic (G.R.P.) laminated sheets have been in use for a number of years and can be drilled using H.S.S. drills although drill wear takes place at a high rate giving an inferior hole quality and delamination of the sheet at the exit side of the hole and, under certain conditions, at the entry side of the hole also. The object of this project was to investigate the drilling of G.R.P. laminated sheet and to make recommendations for good drilling practice when using H.S.S. twist drills. Although of a nominally specified amount, the glass content was found to vary considerably between the sheets used. The sheet with the lower glass content (60.78%) was used to determine the effect of variation in drill penetration rate using standard drills while the sheet with the higher glass content (74.32%) presented much more severe drilling problems through early discolouration of the hole and was used therefore to study the effects of variation in drill geometry on cutting performance. The tests carried out have been quantified in terms of drill quality through the measureable parameters of torque, thrust and drill wear with the establishment of empirical torque and material removal factor (M.R.F.) values and hole quality through the measurable parameters of change in size, shape and surface finish.