Cutting conditions and tool optimization in the high-speed milling of aluminium alloys

Abstract

The high-speed milling (HSM) of aluminium alloys was one of the first fields of application of this technology. It might be thought that this is the field where the technology has been most commonly used, with the largest number of users, and is therefore best known. However, the continuous improvements in modern machine tools on the one hand, together with the development of new tool materials and tool geometries on the other, have produced a constant increase in the cutting conditions (i.e. speed and feed rate). During the past 5 years the use of high-silicon (12–21 per cent) castings has grown considerably owing to the fact that a high silicon content results in excellent properties, mainly wear and high-temperature resistance. However, the machinability of the material becomes too poor on account of its abrasiveness. Aluminium alloys for structural elements in the aeronautical industry are nowadays high-speed milled (HSMed) at very high removal rates, which makes possible the use of monolithic structures instead of sheet metal formed structures. Complete removal of coolant fluids has not been possible so far, but their use can be effectively minimized if techniques such as micropulverization are applied. In this paper, the problems in the machining of the previously mentioned alloys are analysed, along with the possibilities of the so-called minimum quantity of lubricant (MQL) technique.