Abstract:
Traditionally, metal cutting fluid or lubricant is used in finishing operations of die and mould manufacture to reduce the rate of tool wear, which in turn improves surface quality. However, metal cutting fluid has negative effects on the environment, and also increases the total production cost. The minimum quantity lubrication (MQL) technique is considered to provide the same level of performance as the flood coolant method, and offers financial benefits by saving coolant direct and associated costs. It has therefore grown to be an increasingly popular alternative lubrication method in certain HSM applications. In this study, the effects of Near-Dry and MQL machining on surface roughness, tool wear, dimensional accuracy and machining time were compared using the Design of Experiments (DOE) technique. In terms of surface roughness and tool wear, there were no significant differences. Nevertheless, MQL machining produced more accurate results than Near-Dry machining in dimensional deviation. The regression models show that feed-rate has a larger effect on surface roughness and machining time than step-over, while depth of cut has no significant effect on surface roughness. Based on the test piece shape, an optimal machining time of 3.55 hours and a good surface finish of 0.28 µm can be achieved by using a small feed-rate (0.03 mm/tooth), a large step-over (0.1 mm) and a large depth of cut (0.2 mm). When combining the MQL technique with the right cutting conditions in modern die and mould manufacturing, machining time and polishing time can be reduced, which leads to an overall saving in production cost. Using the Near-Dry and MQL techniques for different finish machining situations can therefore be a good economical solution.