Investigation of vibration in micromilling with minimum quantity lubrication: Parameter selection

Micromilling using minimum quantity lubrication (MQL) is proven to reduce the cutting temperature and improve the cutting tool life. However, vibration remains as one of the critical issues. Thus, the objective of this research is to analyse the vibration produced during the process of micromilling with MQL. A high-precision CNC milling machine DT110 (Mikrotools Inc, Singapore) was used to machine microchannels with end milling tool (500 µm diameter, flat end, two flutes, 5 µm edge radius) on a C1100 copper alloy workpiece. The machining process was lubricated using MQL system (Bluebe FK, Fuji BC, Japan) with biodegradable vegetable-based oil. The parameters were the oil flow rate, nozzle air pressure, nozzle direction, spindle speed and depth of cut. Responses parameters were the spindle speed frequency (SSF) amplitudes and SSF chatter amplitudes. The accelerometer was attached onto the high-speed air bearing spindle (ABS-400, Nakanishi, Japan) installed onto the CNC machine DT110. The measured vibration data was recorded by the DAQ system and analysed using Graphtec GL-7000. This research showed that spindle speed, depth of cut, oil flow rate, nozzle pressure and nozzle direction are found to be influential in generating vibration in micromilling. Whereas, feed rate, tool overhang and nozzle distance are found to be not significant in generation vibration.