Minimum quantity dry lubrication in machining of CFRP

In the context of high tool wear concerning machining of carbon fiber reinforced plastic (CFRP), it is desirable to study new processes and techniques which are able to lower the wear and thus induced costs. Therefore, this article presents a novel minimum quantity dry lubrication (MQDL)-process. It delivers minimal amounts of graphite powder, using compressed air as a conveying medium to its operating area between the tool and workpiece. For this purpose a prototypical fluidisation device for conditioning, dosing and conveying the graphite powder was built. The investigations have shown that the constructed prototype is already able to deliver tiniest amounts of graphite mass flows (less than 3 g/h) reliably. Furthermore, first results of drilling tests with internal MQDL-supply are presented. The cutting edge radius of the solid carbide drilling tools has been chosen as the wear measuring quantity. With the use of MQDL at drilling CFRP, a clear reduction in wear is shown, in comparison to pure compressed air. Finally the article shows further research and application areas of this new MQDL-technology.