Fundamentals of cooling/lubrication effect in grinding of Inconel 718 employing an inverse thermo-mechanical model

Cutting fluids are essential in grinding to control the intense heat generated at the wheel–workpiece interface. This study investigates the cooling/lubrication effect using an inverse thermo-mechanical model to support the understanding and optimization of sustainable cooling strategies. A hybrid analytical–experimental method is developed for determining the heat partition ratio and the convective heat transfer coefficient (h), which are critical to understanding thermal behavior in grinding. The inverse modeling approach considers the thermal behaviour of coolants and workpiece materials under elevated temperatures, where their thermo-physical properties differ significantly from those at room temperature. It further incorporates the effects of grinding parameters, wheel-workpiece contact length, and coolant supply conditions. Additionally, chemical reactions in the grinding zone, which can either absorb or release heat, are accounted for, further influencing heat transfer dynamics. The model is applied to evaluate several eco-friendly cooling/lubrication techniques, including cryogenic liquid nitrogen, carbon dioxide, minimum quantity lubrication (MQL), and their hybrid combinations, and compared to conventional flood and dry grinding. Key performance indicators such as grinding forces, temperature, surface finish, and elemental composition are analyzed. A generalized formula for the heat partition ratio is proposed based on the inverse method, enabling consistent evaluation of thermal effects across different cooling conditions. This integrated modeling approach enhances the understanding of coolant behavior in realistic grinding environments and supports the transition toward sustainable, high-efficiency manufacturing by guiding the selection and optimization of environmentally friendly cooling/lubrication methods.