Mueller-Hummel, P., Atarsia, A., and Wiemann, A., "One Shot - Dry - Drilling of Composites / Aluminium Hybrid Stacked Materials in IT8 Quality," SAE Technical Paper 2013-01-2337, 2013, doi:10.4271/2013-01-2337.
This article describes the physical background and the experience in the drilling of carbon fiber and aluminum-carbon fiber stacks. Low temperatures and intelligent chip removal technologies are the most important requirements for dry drilling or to avoid the MQL (minimum quantity lubrication). The drilling in one shot and in IT8 quality is mandatory.In case of machining metal, like aluminum or titanium, a lot of heat is generated by the tools and the cutting process. Machining of composites, the material and the tool should remain as cold as possible even by drilling without external or internal coolant. A new drill design is now developed, qualified and patented by MAPAL that allows the dry drilling of metals at very low temperatures also. We are now able to drill, all batches (composite / aluminum) without MMS. The high drilling feed and due to that, the shorter contact length between the tool and the material stack also gives us approximately twice the tool life. The new tool has already been qualified for drilling stacks in the wing box assembly, without MMS and a CPK value of 2.4. This gives us a new economic method for one-up-and-clean drilling in the assembly. There are lots of criteria to fulfill, that permits the dry drilling at low temperature. The paper points that out. Most of the tools on the market generate a lot of heat. This tools are working perfectly in cutting metal, but they destroy the integrity of the composite surface and create a lot of burrs.