Influence of cutting fluid application frequency on the surface quality of micromilled slots on Inconel 718 alloy

Micromilling is a machining process defined by its low dimensions. In general, it is defined by the cutting tool diameter that must vary between 1 µm and 1000 µm. This process is used mostly in molds, medical applications and Micro-Electromechanical Systems (MEMS), where high quality parts are required in terms of geometry, which are absent of defects and possess smooth surfaces. However, there exist hurdles that need to be crossed in order to achieve these high-quality parts, most frequently surface roughness and the presence of burrs. For such phenomena, one common solution is the appliance of cutting fluids. To this end, some research studies have been developed, these have placed their focus upon the different composition of cutting fluid, which is applied with different pressures and at different rates. The application of cutting fluid can be made through pulses, as this is a common configuration for the MQL fluid supplier. The frequency of pulses defines the volume of cutting fluid applied and consequently affects the results. In this sense, this study aims to evaluate the influence of the frequency of cutting fluid application over the final part of the cutting process. The results demonstrated that for the difficult to cut Inconel 718, if a low frequency of fluid, delivered by MQL, is applied, the final piece will not be homogeneous, as well as leaving parts with a low surface quality and higher burr formation.