Performance evaluation of vegetable oil as an alternative cutting lubricant when end milling stainless steel using tiain coated carbide tools

Abstract

This paper reports the experimental investigations on the use of various cutting fluids when end milling AISI 420 hardened stainless steel using TiAIN coated carbide tool. The cooling techniques include dry, minimum quantity lubrication (MQL), and flood coolant with tool life and surface roughness as the main responses. Particular observation was emphasized on the use of vegetable oil as the coolant in MQL compared to the common fatty alcohol. Machining trials were performed at cutting speed of 100 m/min and feed of 0.03 mm/tooth. The radial and axial depths of cut were maintained at 12 mm and 0.6 mm, respectively. Results showed that both the cooling techniques and the type of cutting fluid used significantly affect the tool life and surface finish of the machined workpiece. MQL technique, especially when using vegetable oil based cutting fluid, outperformed other cooling techniques in terms of tool life. Flood coolant recorded the shortest tool life. Average flank wear was the dominant tool failure mode for all cooling techniques tested, except for flood coolant whereby average flank wear and chippings were the limiting factor for the tool failure. Dry cutting recorded the lowest surface roughness on the machined surface as compared to other cooling techniques. At the selected cutting parameters, particularly when the cutting tool was still sharp, the end milling produced surface finish of finer than 0.8 µm in arithmetical surface roughness (Ra).