Influence of Minimum Quantity Lubrication Using Vegetable-Based Cutting Fluids on Surface Topography and Cutting Forces in Finish Turning of Ti-6Al-4V

Titanium alloys are included in the group of difficult-to-cut materials. The use of different methods to reduce the temperature of the machining zone is one of the factors influencing the performance of the machining. The most commonly used method is flood cooling. On the basis of recent research, the conventionally used cutting fluids can cause some health problems for machine operators. Moreover, it was found that they can cause some problems for the environment during storage and disposal. Therefore, in recent years, the aspects of the use of biodegradable fluids and the reduction of the number of metalworking fluids used in machining processes have received much more attention. In this study, the effect of the application of three different vegetable oil-based cutting fluids was evaluated for minimum quantity lubrication (MQL) in finishing the Ti-6Al-4V titanium alloy on surface topography and cutting force components. The same tests were conducted for dry cutting conditions and the results were compared with those after machining with MQL. It was found that the best surface roughness was obtained with the use of the mixture of 50% vegetable oil and 50% diester (1PR20) under all the cutting parameters considered. The biggest differences in the values of the Sa and Sz parameters can be noticed for the lowest feed rate. For the feed rate f = 0.1 mm/rev, the Sa parameter values were approximately 32% and 24% lower for MQL with 1PR20 compared to MQL to LB2000 and dry cutting conditions, respectively. In terms of cutting force components, the lowest values were obtained for the MQL with 1PR20 machining. The values of the main cutting force were about 15% lower compared to the MQL with LB2000 cutting conditions for all the cutting parameters considered.