javad makarian

Nowadays, steel hardening has received much attention from researchers due to its frequent use in industries, especially is widely used in energy equipment, aerospace, and petrochemical industries. Low capability in chip removal of hardened steel has always been a significant machining issue. Mounted point grinding is a machining method to improve surface finish and remove burrs on the workpiece walls and hard-to-reach areas. This process is usually used without preparing the grinding wheel before and during the grinding operation, which reduces the proper performance of the process. Environmental contamination, surface integrity, coolant-lubricant-related diseases that affect workers' health, and machining costs heavily depend on the appropriate dressing and proper coolant-lubricant usage. In this study, the effect of dressing conditions (depth of dressing and dressing feed) and the workpiece feed rate during the mounted point grinding of a Mo40 hardened steel in two traditional wet and Minimum Quantity Lubrication (MQL) environments has been investigated. Surface roughness and wheel loading are two significant outputs in every grinding operation. The experimental result of this study reveals an improvement in enhancing the surface roughness in a soft dressing condition. Moreover, this study aimed to achieve proper surface roughness by implementing MQL technique to significantly reduce total cutting fluid usage compared to traditional wet machining. This study observed a higher wheel loading in MQL technique than in the conventional wet grinding.

In grinding operation, wheel topography influences the workpiece surface quality, grinding forces, abrasive grain wear and wheel loading. The difficulties associated with grinding nickel-base superalloys are mainly attributed to the high strength and low thermal diffusivity of these materials. Their high strength leads to high removal energy. The application of green machining techniques for sustainable manufacturing becomes more and more attractive nowadays to reduce the consumption of energy and cutting tools and cut fluids and consequently decrease the production costs and environmental effects. In this study, the effect of dressing parameters and wheel topography on Minimum Quantity Lubrication-MQL grinding performance of Nickel-base superalloy-Inconel 738 is investigated. In other words, to generate different grinding wheel topographies, depth of dressing and dressing speed has been changed during dressing and conditioning of vitrified Al2O3 wheels using a single point diamond dresser. After dressing grinding wheels, machining tests have been conducted to study the influence of the wheel topography and coolant-lubricant types on the performance of grinding operation (workpiece surface quality and wheel loading). The tests have been performed in the presence of fluid as well as MQL with compressed air. The results show that applying MQL technique with the optimized dressing conditions improves the grinding performance of Inconel 738. Minimum quantity lubrication implemented in the grinding process is one of the realistic alternatives that can rise the abrasive processes on a sustainable level.

Wheel loading in the grinding process is inevitable due to the chips arrangement separated from the surface of the workpiece in the gap between the grains. The amount of this loading depends on the factors such as workpiece material, grinding parameters, coolant-lubricant conditions and wheel surface topography. Determining the time to remove the chips from the wheel surface is one of the important variables in the grinding process, preventing the chips from sticking to the surface of the wheel and thus increasing the roughness of the surface. There are several methods for analyzing and monitoring the condition of wheel surface. In this study the influence of dressing condition and coolant-lubricant environments on the wheel surface loading has been investigated using image processing in python software. Using the examination of wheel surface images in pre and post grinding process of Inconel 738 under various condition of coolant-lubricant, optimal conditions for grinding wheel surface topography as well as workpiece feed rate are provided to prevent excessive loading.