Uniformity Challenges in Conventional Magnetorheological Polishing

Magnetorheological polishing controls the rheological behavior of a magnetorheological polishing fluid through an external magnetic field. The fluid forms a compliant polishing zone with sufficient stiffness and stability to produce controlled material removal from optical surfaces. In conventional configurations, however, repetitive polishing patterns and nonuniform removal may lead to inconsistent surface quality across the workpiece.**Nonuniform magnetic-field distribution is a major contributor to this problem.** Variations in field strength and spatial distribution change the local stiffness and working behavior of the magnetorheological fluid. As a result, polishing pressure, abrasive interaction, and material removal may differ from one area to another. Optimizing the magnetic-field generator is therefore essential for improving process consistency.

Magnetic-Field Optimization with a Curved Permanent Magnet

To address the limitations of conventional magnetic structures, a **curved magnetic-field generator** was developed. By modifying the pole geometry, the curved permanent magnet provides a means of regulating the magnetic field across the polishing zone. This design is intended to improve field uniformity while strengthening the effective magnetic action required to maintain a stable polishing region.The magnetic-field generator was integrated into a reciprocating cluster-type magnetorheological polishing system with computer-controlled motion. Reciprocation varies the polishing trajectory and reduces localized differences caused by repeated single-direction patterns, while the clustered polishing arrangement expands the effective processing area. The coordinated use of curved magnetic-field control, reciprocating motion, and clustered polishing supports more stable fluid behavior and more consistent material removal.

Experimental Validation on K9 Optical Glass

Planar polishing tests were conducted on K9 optical glass using the reciprocating cluster-type magnetorheological polishing system. The experiments confirmed the feasibility of the curved magnetic-field generator. **The curved permanent-magnet design improved magnetic-field uniformity, resulting in more uniform material removal and better surface quality.**These findings demonstrate that magnetorheological polishing performance is influenced not only by the polishing fluid, abrasive media, and motion parameters, but also by the geometry of the magnetic-field generator. Combining a more uniform magnetic field with controlled reciprocating motion provides a practical approach to reducing localized removal variations and improving the consistency of precision optical-glass polishing