With the development of new harder materials and new products, and advancement of manufacturing technology, fine surface finish is in great demand. New materials have qualities like high temperature resistance, light weight and high corrosive resistance and are used in high-tech industries like aerospace and electronics. The machining of complicated shapes and new materials with conventional-edged tools is uneconomical, and also the degree of surface finish obtained is poor. A relatively new finishing method, Magnetic Abrasive Machining (MAM), can be used to efficiently produce good quality surface finish of new materials and complicated shapes. The magnetic abrasives play a vital role in MAM, and only a few studies are available regarding the use of lubricants in MAM. In the present study, the performance of dry magnetic abrasives was compared with wet magnetic abrasives when used for the internal finishing of brass tubes. To make the magnetic abrasives wet, high speed diesel (20% by weight) was used as the lubricant. It has been found that the improvement in surface finish and Material Removal Rate (MRR) was more in the case of wet magnetic abrasives, as compared to the dry magnetic abrasives. The maximum improvement in surface finish with dry magnetic abrasives was around 55%, while in the case of the wet magnetic abrasives, it was up to 70%. The improvement in MRR with wet magnetic abrasives was remarkable (around 100%).

Magnetic abrasive processes are more efficient and produce a better surface finish than the conventional methods of finishing operations (super finishing, belt grinding, polishing and honing), as confirmed by the experimental investigations and industrial use. The processes are suitable for different applications due to small chip size and self-sharpening of the tool. The machining of hard and Difficult-To-Machine (DTM) materials is also possible by these processes (Insaki et al., 1993). After rough turning operation, a workpiece can be directly finished with these processes without using any intermediate machining processes, such as grinding, honing and lapping (Kremen et al., 1996). Finishing of flat and cylindrical surfaces (internal and external) and balls is possible with acceptable range of surface characteristics.

The magnetic abrasives used in Magnetic Abrasive Finishing (MAF) processes have been prepared earlier by different techniques like sintering of iron and abrasive particles, plasma powder melting technique, bonding of iron and abrasive particles with glue (Chang et al., 2002), mixed magnetic abrasives and unbonded/loosely bonded magnetic abrasives (Shinmura and Yamaguchi, 1995; Feygin et al., 1998; Yamaguchi and Shinmura, 2000; and Yamaguchi and Handa, 2008).

Shinmura and Aizawa (1989a) used 15 wt.% straight oil type grinding fluid for internal finishing of stainless steel tubes and found that MAF is capable of surface finishing without affecting the shape of the workpiece. Shinmura and Aizawa (1989b) used 20 wt.% of straight oil type grinding fluid and magnetic aluminum oxide abrasives for finishing a plane surface. Shinmura and Yamaguchi (1995), using 7 wt.% of the straight oil type grinding fluid and mixed-type magnetic abrasives for internal finishing of the tube and clean gas bomb, achieved 0.2 mm Rmax surface finish. Some researchers used the lubricating oil to bind abrasives and iron particles and found that low or excessive quantity of the oil results in, respectively, poor surface finish or less stock removal, as the lubricating oil forms a film between brush of the magnetic abrasives and the workpiece (Jain et al., 2001; Chang et al., 2002; and Yamaguchi and Shinmura, 2004). A few studies are available in which Magnetic Abrasive Machining (MAM) was carried out in dry and wet conditions using bonded magnetic abrasives. In the present study, the machining was carried out using bonded magnetic abrasives in dry and wet conditions, and the performance of the process was compared for a brass component. High speed diesel (20 wt.%) was used as the lubricant. Experiments were carried out to compare the performance at various machining conditions.

Mechanical Engineering Journal, Internal Surface Finishing, Brass Tubes, Wet Magnetic Abrasives, Magnetic Abrasive Machining, Non-Ferromagnetic Tubes, Magnetic Flux Density, Dry Machining, Vibration Modes, Manufacturing Technologies, Material Removal Rate.