A study of the surface texture of composite drilled holes

Abstract An investigation of the surface texture of composite drilled holes was conducted by drilling experiments at constant speed with two different PCD tipped drill geometries at varying feed rates. Surface profilometry was used to measure the surface roughness profiles of machined graphite/epoxy holes and roughness characteristics were evaluated using average roughness heights, statistical methods, and random process methods. It was found that the width of damage in a composite material is a function of the drill geometry and the feed rate. All the surfaces studied were found to be non-Gaussian, negatively skewed, leptokurtic, and produced a good bearing surface. The use of maximal roughness height parameters, power spectral density function, and cumulative height density plotted on a probit scale allows characterization of the texture of the surfaces of the drilled holes.