In process temperature and tool wear for the machining of aeronautic aluminum under different lubrication conditions

Abstract

The use of aluminum-lithium alloys in aeronautics is an efficient solution for lightweight structures, but its machinability can cause increased tool wear. The cutting temperature is one of the most important parameters controlling the tool wear and the quality of machined surfaces. Therefore, its measurement is of great interest to analyze the heat generation during the cut and then being able to limit it in the cutting edge. This article presents an original experimental study of the cutting temperature of two aluminum alloys (7000 series and Li-containing 2000 series), for dry, MQL: Minimum Quantity of Lubrication and wet machining conditions. The interactions between tool wear and cutting temperature are also investigated. To be able to observe tool wear, the milling of very large volumes of aluminum alloys has been necessary since the tool lifetime is several hours when machining this kind of material. To measure temperature as close as possible the cutting zone, an original set-up with machinable thermocouples was used, enabling measurements on a large frequency bandwidth. Complementary investigations by Second Ion Mass Spectroscopy revealed a diffusion of lithium in the cutting insert, which can reduce its lifetime (divided by 8, with the Li-containing 2000 series compared to the 7000 series).