Use of castor oil as cutting fluid in machining of hardened stainless steel with minimum quantity of lubricant

Abstract

Use of cutting fluids in machining processes can reduce the cutting temperature and provides lubrication to tool and workpiece. These translate to longer tool life and improved surface quality. Due to the issues of using fluids in machining related to environment, health, and manufacturing cost that need to be solved, options to reduce their use. A technique called minimal quantity lubrication (MQL), which sprays small amount of cutting fluid (in the range of approximately 10 – 100 ml/h) to the cutting zone area with the aid of compressed air, was developed to merge the advantages of both dry cutting and flood cooling. For the type of cutting fluids, vegetable oils are common cutting fluids used in MQL because of its superior lubrication and high-pressure performance. This study evaluates the performance of MQL using castor oil as cutting fluid. The workpiece is hardened stainless steel 48 HRC. Results are compared with dry cutting. It was found that using small amount of lubricant of 50 ml/h during the particular turning process produces better results compared to dry cutting, in terms of longer tool life. Surface roughness and cutting forces were also enhanced albeit slightly. From the results, MQL can be a good technique for turning hardened stainless steel using coated carbide cutting tools for cutting parameters of up to 170 m/min cutting speed and 0.24 mm/rev feed.