DEVELOPMENT OF MINIMUM QUANTITY LUBRICANT DEVICE FOR TURNING PROCESS

Abstract

Minimum quantity lubrication (MQL) uses a very small lubricant flow (ml/h instead of l/min) and directly sprayed the lubricant on the cutting zone which guarantee a good level of lubrication and the chip removal mechanism; besides the economic benefits, one other important advantage is being environmentally friendly. This study developed an 80 % local content MQL device and carried out a performance evaluation by investigating the effect of flow characteristics, cutting velocity, feed rate and machining time on surface finishing for turning AISI 1018 mild steels. The developed MQL device was adapted with Harrison M400 lathe for the turning operation in which high speed steel (HSS) was used as the cutting tool and groundnut oil (vegetable oil) was used as the cutting fluid. Different ratios of air to oil (A/O) were used within the range of 1 to 5 bar. The result showed that the surface roughness Ra, progressively decreases with increase in A/O ratio at relatively low A/O value but this phenomenon ceased at a critical value of A/O of 1.5 and an increase in A/O resulted to an increase in Ra. Thus, A/O ratio of 1.5 (air compressor fixed at 3 bar and micropump at 2 bar) achieved the best surface finish having Ra of 0.95 µm and taken as optimum A/O value for MQL turning operation for mild steel. Further findings showed that the surface roughness, Ra increases with the increase in feed rate and decreases with the increase in cutting velocity Vc. Also, surface roughness gradually increases with the machining time. Therefore, A/O ratio of 1.50 is recommended as an optimum value for MQL turning operation for mild steel.