Wear and cost issues in magnetic fluid grinding

• Published in: Wear Vol. 249; no. 5; pp. 509 - 516
• Main Authors: Childs, T.H.C., Moss, D.J.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01-06-2001; Amsterdam Elsevier Science; New York, NY
• Subjects: Abrasive wear; Applied sciences; Ceramic ball-grinding; Contact of materials. Friction. Wear; Exact sciences and technology; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Resin-bonded diamond; Abrasive wear; Ceramic ball-grinding; Resin-bonded diamond; Non metal; Ball mill; Diamond tool; Silicon nitride; Machining; Magnetic fluid; Experimental study; Grinding; Rolling bearing; Concentrated load; Ball bearing; Grinding wheel; Non viscous fluid; Ore grinding; Shaft; Cutting fluid; Ceramic materials; Surface grinding
• ISSN: 0043-1648; 1873-2577
• DOI: 10.1016/S0043-1648(01)00584-1

The grinding surface in magnetic fluid grinding (MFG) was originally created by embedding initially loose grits into a metal grinding shaft. Developments have included replacing the magnetic fluid by a cheaper, viscous, non-magnetic fluid, and loose grit/metal shafts by pre-manufactured resin-bonded or electro-plated diamond grinding surfaces. This paper reports grinding rates and grinding ratios, and diamond consumables process costs, for both the original and the resin-bonded or electro-plated grinding surface processes, for finish-grinding silicon nitride ceramic ball bearings. Grinding rate is reported as ball diameter reduction per unit time. Grinding ratio is the ratio of volume lost from the ground surface to volume lost from the grinding surface.
In no case has a grinding ratio greater than 10 been achieved. In other tests, surface grinding the same grade of silicon nitride with peripheral grinding wheels of the same resin-bond, diamond type, size and concentration as in MFG, in conditions that cause similar grit loads as in MFG, grinding ratios have been achieved greater than 100.
The 10-fold lower grinding ratio in MFG may be due to point-contact conditions whereby load may be carried directly on the matrix or bond between the grits of a grinding surface, thus, creating more damage than in the plane contact conditions of surface grinding. Alternatively, it may be due to a greater number of impacts between the ground surface and grits, per volume removed, caused by the inherently short abrasive scratch length in MFG; or it may result from erosion of the bond by MFG’s inherently viscous process fluid.