Innovative drills for composite machining at Aero Engineering

Composites are set to become the predominant material used in aircraft manufacture over the next three to five years. They are, however, more brittle than metals, and their machining has brought new challenges. David Goulbourne, development manager for drills at Dormer, explains: "Machining of composite materials can cause problems such as delamination between layers at a hole entry or exit, fraying, hole erosion and splintering. The new drill, developed in cooperation with the University of Sheffield Advanced Manufacturing Research Centre with Boeing in the UK, addresses these issues, providing the perfect solution for the market." Designed for use in Polymer Matrix Composites (PMCs), also known as Fibre Reinforced Polymers (FRPs), the drills work equally as well in Carbon Fibre Reinforced Polymers (CFRPs) and Glass Fibre Reinforced Polymers (GFRPs). The range features a unique, patented point design which reduces thrust and torque requirements. This improves cutting efficiency and significantly reduces splintering and delamination at exit. There is an internal coolant option for wet machining and a diamond coated option to further enhance tool life. The range is available from 2.38 mm to 20 mm diameter and with overall lengths up to 310 mm as a special order, allowing the end user to specify their own requirements, including sizes, applications and cutting conditions.