A Novel Method to Assess Aluminium Alloy Machinability Using Shear Cracks in Chips Formed During Machining

Demand for aluminium (Al) products has increased due to their low density, high strength-to-weight ratio, thermal and electrical conductivity, and corrosion resistance. Reliable machinability assessment is important for selecting suitable alloys for manufacturing applications. However, conventional methods based on chip counting and weighing may not adequately distinguish alloys with similar chemical compositions. This study proposes an alternative method for assessing aluminium alloy machinability by quantifying the Shear Crack Initiation Layer (SCIL) in machining chips. Aluminium alloys were machined using a lathe under consistent machining parameters, and chip cross-sections were examined to quantify shear crack features and investigate differences between inner and outer chip layers. Conventional chip counting and weighing produced similar machinability values for two chemically similar alloys and showed negligible differences between the inner and outer layers of each alloy. In contrast, SCIL-based assessment revealed clear machinability differences between the inner and outer layers within each alloy and between the two chemically similar alloys. These findings demonstrate the potential of SCIL quantification to provide a more sensitive assessment of aluminium alloy machinability than conventional chip counting and weighing methods.