Interaction Between Ferroabrasive Medium and Surfaces of Parts During Magnetic Abrasive Finishing in Large Ring-Shaped Working Gaps

Abstract

Experimental studies were conducted to examine the drag forces in the finishing of ferromagnetic and paramagnetic samples shaped as bars with square and equilateral triangular cross-sections, having a side length of 16 mm. Variations in the total drag forces exerted by the magnetic abrasive tool (MAT), composed of magnetic abrasive powders of various types and particle sizes, on the movement of samples within large ring-shaped working gaps were analyzed to determine the percentage contributions of the drag force components. The drag forces most significantly depended on the midship section of the parts and were determined by the magnetic forces and the degree of powder compaction between the side surfaces of the samples and the pole tips. The drag forces associated with the midship section during magnetic abrasive finishing (MAF) constituted up to 60–65% of the total drag forces from the MAT side for ferromagnetic samples and 80–85% for paramagnetic samples. The contribution of friction forces unrelated to the action of magnetic forces did not exceed 10–15%. A significant share of the drag forces on the MAT side, reaching 25%, was attributed to the magnetic pressing of powder particle groups against the surfaces of ferromagnetic samples near the pole tips within the working area. The features peculiar to the movement of MAT particles in the finishing of ferromagnetic and paramagnetic parts were established. These features define the prevailing friction mechanisms in the finished surface–MAT contact areas, occurring between the side surfaces of the parts and the pole tips. Thus, sliding friction forces prevail in the finishing of ferromagnetic parts, whereas rolling forces dominate for paramagnetic parts, determining the conditions for forming finished surfaces through predominant microcutting or microplastic deformation.