Performance Evaluation of Cryogenic LN2 Coolant on Surface finish and Chip morphology in Machining 7075 Aluminium alloy

This paper presents experimental investigations on surface finish and chip morphology
during the machining of a 7075 aluminium alloy bar, comparing the use of Cryogenic Liquid
Nitrogen (LN2) against a conventional coolant in turning operations. The analysis of chip
thickness, form, and morphology, alongside surface roughness measurements, revealed that
employing cryogenic coolant significantly improved the process outcomes. Specifically, the
thickness of the metal chips was reduced by 6 to 20%, and the surface finish was enhanced by
15 to 23% under cryogenic machining conditions compared to those using a conventional
coolant.
Keywords: 7075 aluminium alloy; LN2 cooling; chip thickness; surface roughness