Study on the behavior of the minimum quantity lubricant - MQL technique under different lubricating and cooling conditions when grinding ABNT 4340 steel

Abstract

Energy consumption, air pollution and industrial waste have received special attention from public authorities in recent years. The environment has become one of the most important subjects in the context of modern life, for its deterioration impacts the quality of life populations. Driven by pressure from environmental agencies, politicians have drawn up ever stricter laws aimed at protecting the environment and preserving energy resources. All these factors have led industry, research centers and universities to focus their efforts on researching alternative production processes, creating technologies to minimize or avoid the production of environmentally aggressive residues. Up to a few years ago, the main objective of manufacturing plants was to produce goods aimed at satisfying technological and economic aspects. Green, or "dry" machining and Minimum Quantity Lubricant (MQL) machining have caught the attention of researchers and technicians in the area of machining as an alternative to traditional fluids. Thus, this work proposes to explore the MQL concept in the grinding operation. Although its advantages allow one to predict a growing range of applications for MQL, the variables of influence to be considered and the effects on the results of the process have so far been little studied. Grinding involves several input parameters but, to date, little attention has been focused on the form and quantity of cutting fluid applied to the process. The condition and rate of cutting fluid applied directly influences some of the process's output variables. This work, therefore, analyzes the behavior of the MQL technique under different lubrication and cooling conditions, developing an optimized fluid application methodology based on the creation of a special nozzle through which a minimum amount of oil is pulverized in a compressed air stream. The evaluation of the technical performance of MQL in grinding, using aluminum oxide and superabrasive CBN (cubic boron nitride) grinding wheels, consisted of an experimental analysis of the behavior of the tangential cutting force, G ratio, roughness and residual stress. The results presented herein allowed us to evaluate the behavior of the MQL technique in the grinding process, thus contributing toward an environmentally friendly technology

Minimum Quantity Lubrication Assisted Turning - An Overview

“…Air in the aerosol provides the cooling function and chip removal, whereas oil provides lubrication and cooling by droplet evaporation. The flow of lubricant in MQL process varies from 10 to 100 ml/h and air pressure varies from 4 to 6.5 Kgf/cm 2 (Silva et al, 2005). Different ranges for flow rate were also reported in literature such as 50 to 500 ml/h (Dhar et al, 2006a) and 2 to 300 ml/h (Zhong et al, 2010).…”

Optimization of Ceramics Grinding

“…Some researchers investigated the effects of grinding parameters on AISI 4340 steel grinding using conventional lubrication and MQL. They found that the surface roughness, diametric wear, grinding forces and residual stress improved when using the latter, due to optimum lubrication of the grinding zone, providing rather grain slipping at www.intechopen.com the contact zone (Silva et al, 2005;Silva et al, 2007). Brunner showed that the MQL grinding with a 4 ml/min ester oil (comparing to 11 ml/min mineral oil), when machining 16MnCr5 (SAE-5115) steel with microcrystalline aluminum oxide reduced the process normal and tangential forces to one third, however increasing the surface roughness by 50% (Tawakoli et al, 2009).…”

“…Hafenbraedl and Malkin found that MQL provides efficient lubrication, reduces the grinding power and the specific energy to a level of performance comparable or superior to that obtained from conventional soluble oil (at a 5% concentration and a 5.3 l/min flow), while at the same time it significantly reduces the grinding wheel wear. However, it presented slightly higher surface roughness values (Ra) (Hafenbraedl & Malkin, 2001;Silva et al, 2005;Silva et al, 2007). The performance was also assessed when applying dry grinding.…”

FEM Simulation and Analysis of Temperature Field of Environmental Friendly MQL Grinding

“…Experimental study on grinding of cast iron by using various nanofluid lubricating mixtures gives positive improvement in surface finish, and G ratio. [4]. Cong Mao et al had reported MQL grinding is more environmental friendly and economic for AISI 52100 steel [5].…”