Removal rate model for magnetorheological finishing of glass

Abstract

Magnetorheological finishing (MRF) is a deterministic subaperture polishing process. The process uses a magnetorheological (MR) fluid that consists of micrometer-sized, spherical, magnetic carbonyl iron (CI) particles, nonmagnetic polishing abrasives, water, and stabilizers. Material removal occurs when the CI and nonmagnetic polishing abrasives shear material off the surface being polished. We introduce a new MRF material removal rate model for glass. This model contains terms for the near surface mechanical properties of glass, drag force, polishing abrasive size and concentration, chemical durability of the glass, MR fluid pH, and the glass composition. We introduce quantitative chemical predictors for the first time, to the best of our knowledge, into an MRF removal rate model. We validate individual terms in our model separately and then combine all of the terms to show the whole MRF material removal model compared with experimental data. All of our experimental data were obtained using nanodiamond MR fluids and a set of six optical glasses.

Polishing characteristics and mechanism in magnetorheological planarization using a permanent magnetic yoke with translational movement

“…9. Our result that the tangential force has made primary contribution to the material removal is consistent with the work of DeGroote, Shorey and Miao [20,21,24]. Although the tangential force played a dominant role in material removal in this work, the normal force also helped engage abrasive grits with the work material.…”

“…Magnetorheological (MR) finishing has been widely used for polishing mirror surfaces [13][14][15][16][17][18][19][20][21] with promising removal efficiency. In our previous work, we developed a MR planarization process which uses a permanent magnetic (PM) yoke with a straight air gap [22].…”

Tribological Properties of a Magnetorheological (MR) Fluid in a Finishing Process

“…Defining the effective friction coefficient µ that satisfies τ w ≡ µP, [6] µ can be obtained through the comparison of Eq. [3] with Eq. [6], which results in…”

“…In this study, however, we do not attempt to do so and only the two most fundamental terms (µ s and µ l in Eq. [7]) are retained.…”

“…They also showed that this MRR model is well matched with the experimental data within the ranges of R 2 = 0.7-0.86, where R 2 is the regression coefficient of determination. DeGroote, et al (7) further developed this model through the inclusion of the near surface mechanical properties, abrasive size and concentration, glass chemical durability, and glass average single bond strength and quantified the effect of each term on the MRR by performing various experiments. Schinhaerl, et al (8), (9) performed a mathematical modeling study that takes into account process parameters, such as the wheel speed, the magnetic field strength, and the fluid flow rate, to predict the shape and size of the influence function that contains the information about the material removal characteristic of the polishing tool on high-quality optical lenses, and they experimentally verified the effectiveness of their model.…”