Surface Integrity in Machining Solution-Treated and Aged 2024-Aluminum Alloy, Using Natural and Controlled Contact Length Tools. Part I—Unlubricated Conditions

Abstract

The effects of cutting speed, chip-tool contact length and tool surface finish on the surface integrity of a solution-treated and aged 2024-Aluminum alloy, that is machined under dry, orthogonal conditions are investigated. The surface region of machined workpieces is examined using a wide variety of diagnostic techniques. In addition, tool forces are measured and both the cutting geometry and cutting temperatures are calculated. The results of the investigation show that a wide variety of geometrical surface features are generated that contribute to the natural surface roughness. The results also show that a plastically deformed surface region is generated that contains variations in hardness, microstructure and residual strain. The results of the investigation are interpreted in terms of the type of chip produced, formation of the built-up edge, the mechanics and thermodynamics of the cutting process and the interaction between the tool nose region and freshly machined workpiece surface.