Effect of coatings and tool geometry on the dry milling of wrought aluminium alloys

The work presented here is focused on the elimination of coolants in the high speed milling of wrought aluminium alloys. This is a very interesting issue from the point of view of the high costs of the coolant life cycle and for environment preservation. The main factor to be considered is the estimation of temperature at the tool/chip interface, since it acts directly on the tool degradation mechanism: the previous diffusion and the later adhesion of aluminium on the rake and clearance faces, the well-known BUL (built up layer) effect. Two techniques are discussed to keep the temperature below the diffusion threshold, the tool geometry optimisation making use of the simulation of the removal process using the finite element method and the measurement of the tool edge temperature with an infrared L device. Five different types of hard metal tools have been tested under the same conditions.