Shear Stress in Magnetorheological FInishing for Glasses

Journal Article · Tue Apr 28 00:00:00 EDT 2009 · Applied Optics

DOI:https://doi.org/10.1364/AO.48.002585· OSTI ID:951624

Miao, C ^[1]; Shafrir, S N; Lambropoulos, J C; Mici, J; Jacobs, S D

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1. Laboratory for Laser Energetics, University of Rochester, Rochester, NY

We report in situ, simultaneous measurements of both drag and normal forces in magnetorheological finishing (MRF) for what is believed to be the first time, using a spot taking machine (STM) as a test bed to take MRF spots on stationary parts. The measurements are carried out over the entire area where material is being removed, i.e., the projected area of the MRF removal function/spot on the part surface, using a dual force sensor. This approach experimentally addresses the mechanisms governing material removal in MRF for optical glasses in terms of the hydrodynamic pressure and shear stress, applied by the hydrodynamic flow of magnetorheological fluid at the gap between the part surface and the STM wheel. This work demonstrates that the volumetric removal rate shows a positive linear dependence on shear stress. Shear stress exhibits a positive linear dependence on a material figure of merit that depends upon Young’s modulus, fracture toughness, and hardness. A modified Preston’s equation is proposed that better estimates MRF material removal rate for optical glasses by incorporating mechanical properties, shear stress, and velocity.

• Research Organization: Laboratory for Laser Energetics, University of Rochester
• Sponsoring Organization: USDOE
• DOE Contract Number: FC52-08NA28302
• OSTI ID: 951624
• Report Number(s): DOE/NA/28302-887; 2008-178; 1866
• Journal Information: Applied Optics, Journal Name: Applied Optics Journal Issue: 13 Vol. 48; ISSN 0003-6935
• Country of Publication: United States
• Language: English