Hitesh Mhatre, Amrut Mulay
Polycarbonate is tough and impact-resistant polymer widely used in optical, automotive, and medical applications. This study examines the effect of lubricant type, forming temperature, and step depth on the formability of polycarbonate sheets during Single Point Incremental Forming (SPIF), with a focus on forming depth, surface roughness ( R a ), and angular deviation. Experiments were conducted using three lubricants, 5W30 oil, coconut oil, and liquid soap over a temperature range of 30–180 °C and step depths of 0.2–0.6 mm. The Analysis of variance revealed that temperature was the most influential parameter, contributing 60.38% to forming depth, 91.43% to surface roughness, and 39.11% to angular deviation, followed by lubricant type. Step depth showed a negligible effect within the investigated range. A significant interaction between lubricant and temperature was observed for surface roughness and angular deviation, confirming the dominance of thermo-tribological mechanisms. Among the lubricants, 5W30 oil demonstrated superior formability, achieving a maximum forming depth of 21.4 mm and the lowest surface roughness ( R a ) of 0.218 µm at 30 o C and 180 °C, respectively. Coconut oil produced a minimum angular deviation of 1.15° with an acceptable surface finish. However, it reduced the forming depth, making it suitable for precision-oriented applications. Overall, the results confirm that the SPIF of polycarbonate was primarily governed by thermal and tribological effects, providing quantitative guidance for comparative process evaluation.