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

Abstract

The effects of cutting speed, chip-tool contact length, and tool surface finish on the surface integrity of solution-treated and aged 2024-aluminum alloy, that is machined under lubricated orthogonal conditions are investigated. The surface region of machined workpieces is examined using a variety of diagnostic techniques. In addition, tool forces are measured and the cutting geometry is determined. The results show that a variety of geometrical surface features are generated that contribute to the natural surface roughness, and that a plastically deformed surface region is generated that contains variations in hardness, microstructure, and residual plastic strain. The results are interpreted in terms of the type of chip produced, the mechanics and thermodynamics of the cutting process and the lubricating action of cutting fluids. When the results of the investigation are compared with similar results derived under nonlubricated conditions, it is found that at low cutting speeds application of a lubricant produces a reduction in tool forces, power consumption, surface roughness, surface defects, and subsurface deformation, whereas at high cutting speeds application of a lubricant has little influence on the cutting process.