Improvements in grinding of commonly used steels by minimum quantity lubricants(MQL)

Abstract

Grinding is one of the most rigorous machining processes where material is removed from a surface with constant friction and rubbing of abrasive grits attached to a cylindrical grinding wheel. High temperature is generated at the workpiece-wheel interface due to this rubbing and friction. This high temperature generated in the grinding zone adversely affects the physical properties of the ground surface in terms of induced surface and sub surface residual stress, surface roughness, micro cracks and dimensional deviation. So the control over this temperature is a matter of great interest of researchers in the recent years. Conventional sulfur based cutting fluid has several detrimental effect on environment like soil contamination and disposal of toxic gases in the atmosphere. They also have severe impact on the human health of who perform machining in the wet condition. So the application of alternate cooling environment like Cryogenic cooling (Liquid N2), High pressure coolant (HPC), Minimum Quantity Lubrication (MQL), Compressed Cold Air are studied by many researcher and their performance is evaluated with process parameters like Tangential and normal grinding forces, residual stress, surface roughness, surface bum and wheel loading. The application of MQL in grinding operation has both economical and environmental advantages over the. other cooling techniques. The performance of MQL in respect of grinding temperature, surface roughness, residual stress and other performance parameters are studied by researchers for different wheel-work combinations but not in extensive way. Still there are scopes to investigate new combinations to assess the performance of MQL cooling environment in plane surface grinding. Numerical modeling of cutting temperature under MQL condition is still in developing stage. This research mainly focuses on the numerical and predictive modeling of grinding zone temperature and surface roughness for grinding medium carbon XVI steel at industrial speed and feed under MQL cooling condition with two different type of wheel. The experimental result indicates that grinding AISI 1045 steel under MQL condition is more effective and generates much lower grinding zone temperature compared to grinding under dry condition. Again for both dry and MQL environment CBN wheel results lower grinding zone temperature than Alumina wheel. A finite element model is developed by ABACUS/CAE to numerically predict the temperature distribution of the grinding zone along the contact length In MQL environment. The model is validated by comparing with the result obtained from traditional heat transfer model and found to be satisfactory. Based on the experimental result of Surface roughness for grinding AISI 1045 steel under MQL condition a predictive Response Surface model is developed. Three process parameters are considered for surface roughness prediction such as, Wheel speed, work speed and infeed. Strong interaction is found between the listed parameters and their main effect is also found prominent to predict desired surface roughness value. The model is then checked and validated by comparing with experimental data and found reasonably accurate with slight variation which is the general consequence of any natural process.