Recurrence Analysis and Feed Force in Drilling of Polymer Composites

This study relates to drilling of polymer composites. Composite drilling results from the impossibility of making precise holes in the first stage of composite production, i.e. in the molds. Making holes is associated with the problem of delamination, i.e. the fracture of the fiber reinforcement at the tool exit. A drill with a TiAlN coating applied by the PVD technique was used in the study. The paper presents the results of feed force measurement made in the drilling of polymer composites with glass, carbon and aramid fibers. The results showed that the highest feed force values occurred in the drilling of aramid fiber-reinforced plastics (820 N), while the lowest ones when drilling glass fiber-reinforced plastics (130 N). It was found that feed per revolution had the most significant impact on the feed force values. Each type of fiber of composite cause the feed force to increase, but the increase is most observed for drilling aramid fiber reinforced plastics. For composites reinforced with glass fibers, the feed force values are in the range of 130-400 N, with carbon fibers 420-650 N, with aramid fibers 480820 N. The measured feed force values were also used to determine recurrence quantifications sensitive to changes in the technological parameters of drilling. An analysis of the drilling process by the recurrencemethod showed that determinism, longest diagonal line, entropy and laminarity were the most sensitive to variations in the drilling parameters. These indicators would change their values (decrease or increase) with changes in the values of feed per revolution and cutting speed.