Influence of cooling air direction on tool wear and hole quality in CFRP drilling

In the drilling of carbon fibre reinforced plastic (CFRP) components, the cooling process is usually adopted to prolong the tool life and improve the machining quality. Among them, air cooling technology is widely used in actual processing because of its convenience. However, there is a lack of research about air cooling direction on tool wear and machining quality. In this paper, by controlling the flow direction of cooling air, an experimental study of drilling CFRP materials was carried out under dry drilling, forward jet cooling and reverse suction cooling. Meanwhile the change regulation of tool wear on the secondary cutting edge of the double apex angle drill tool was acquired. It is found that gas cooling can effectively restrain tool wear. Under the similar influence of exit temperature by gas cooling, the reverse suction cooling can better effectively restrain the tool wear than forward jet cooling. Furthermore, the inhibition effect of cooling conditions on drilling export damage was analysed, it is found that the tear of hole exit is less restrained by cooling and cooling ways. The height of burrs, however, is restrained obviously by the cooling ways. The reverse suction cooling can effectively reduce the height of burrs. It can be a suitable cooling process in drilling CFRP.