Abstract
This study investigates the comparison between wet and dry machining conditions during the conventional turning of Nitinol Shape Memory Alloy SMA, with a focus on optimizing surface roughness (Ra) and material removal rate (MRR). Nitinol, which is recognized for its unique mechanical properties and growing demand, posed significant challenges during traditional turning processes. Its high hardness and tendency to work hard leads to excessive friction and heat build-up in the machining zone, particularly under dry conditions. To analyse critical relations and variations of input parameters (spindle speed, feed rate and depth of cut) to the responses (surface roughness, MRR and tool wear), a Taguchi L9 orthogonal array approach is used. Cutting parameters under both wet and dry machining conditions are modelled for 3 factors at 3 levels, with two 50 mm diameter Nitinol bar work pieces, one for dry and one for wet conditions, used over a constant length of 150 mm. The effects of cutting speed, feed rate, and depth of cut on Ra, MRR and Tool wear (Vb) are evaluated and analysed to establish the optimal parameters. Results showed that wet machining provides an overall average superiority in surface roughness, reduced tool wear and moderate MRR when compared to that of dry machining. Furthermore, the Taguchi method and experimental results revealed the most significant parameters influencing Ra and MRR, providing valuable insights for improving the efficiency and longevity of tool inserts in conventional turning processes when machining Nitinol SMA. This study contributes to enhancing the understanding of the machining behaviour of Nitinol SMA and offers practical recommendations for the optimization of machining conditions.