A multicriteria model for cutting fluid evaluation

This paper describes the results of a comprehensive evaluation programme for cutting fluid efficiency, when machining the aerospace 'superalloy', Inconel 718. The machining methods used were milling, drilling, tapping and VIPER grinding. Results from three cutting fluids were evaluated: a water-based semi-synthetic, a water-based synthetic and a high-oil emulsion fluid. Cutting forces, torque and spindle power were acquired during machining, while geometrical accuracy, surface texture and surface integrity of the workpiece were analysed afterwards. The experimental results demonstrate the difficulty of identifying the 'best' cutting fluid, especially when several different machining methods are to be employed on the same machine tool. It is unlikely that a single fluid will show the best performance on all machining trials and output measures. Therefore, prioritization of the output measures and specification of the relative importance of each machining operation becomes essential, in order to evaluate and rank the cutting fluid efficiencies. A flexible multicriteria model for the evaluation of cutting fluid efficiency, relative to the performance of a benchmark fluid, is proposed and described. The advantage of the model consists in its flexibility and capability to compare the efficiency of cutting fluids across different machining methods and output criteria. An application of the evaluation model is provided, using results from the tested cutting fluids.