Polishing characteristics of optical glass using PMMA-coated carbonyl-iron-based magnetorheological fluid

Abstract

Soft magnetic carbonyl iron (CI) particles for magnetorheological (MR) polishing encounter corrosion problems as a result of their oxidation, leading to unpredictable polishing results. To overcome this issue, CI particles have been coated with either polymer or inorganic materials for improved MR polishing. In this study, CI particles were coated with poly(methyl methacrylate) to achieve improved MR polishing and anti-corrosion protection. In addition to an analysis of their rheological properties, a series of MR polishing experiments were performed to investigate the material removal rate and surface roughness for BK7 optical glass by changing experimental parameters, such as the wheel rotating speed and magnetic field intensity. A very fine surface roughness (Ra = 0.86 nm for PMMA coated CI/Ra = 0.92 nm for pristine CI) was obtained at a wheel speed of 1256 mm s −1 and a magnetic field intensity of 15.92 kA m −1 .

Systematic Review on the Effects, Roles and Methods of Magnetic Particle Coatings in Magnetorheological Materials

“…A reasonably smooth coating with some surface irregularities was produced, while the sedimentation stability of the MRF was enhanced. A similar work of grafting a PMMA coating onto CIP via dispersion polymerization has also been accomplished by Lee et al (2015) [ 57 ], but with further characterization on the performance of the coated CIP in MRF for the application of optical polishing. It was reported that the sedimentation ratio and anti-corrosion property of the coated material had increased, although the yield shear stress of the coated material in a magnetic field was lower than that of uncoated material.…”

“…In other work conducted by Lee et al (2015) [ 57 ], the CIP was coated with PMMA to be applied in their own MR polishing fluid system. They discovered that by using PMMA-coated CIP in their MRF, the material removal depth of the BK7 glass workpiece was lower while exhibiting lower surface roughness than that of the uncoated one with an optimum rotating wheel speed of 1884 mm/s.…”

“…The effects of corrosion in MR materials have also been discussed in detail by Plachy et al (2018) [ 17 ] and Burhannuddin et al (2020) [ 63 ] in separate works around MRF and MRE, respectively. Furthermore, rougher surfaces of oxidized particles may lead to irregular polishing performance as well as reducing the lifetime of the vessels that contain the MR materials, because rougher surfaces can cause unnecessary friction between the particles and the wall of the vessels after a long operational period [ 57 , 58 , 64 ]. These problems can be minimized by developing coatings that act as a barrier to the oxidation species.…”

Investigation of Polishing Characteristics for Aspherical Lenses Manufacturing

“…Cerium oxide pellets [8] or soft-magnetic particles with magnetorheological fluid [9] could be used to make the polishing process more effective, yet these technologies can cause trouble in CNC polishing machining. The elastic properties of the pad material change in the polishing time, but they do not have the main influence on the surface quality [10].…”

Experiment Plan for Researches of Polishing Process of Optical Details / Optinių Detalių Poliravimo Proceso Eksperimentinio Tyrimo Planavimas

“…Atlikti tyrimai su polimerais ar kitomis neorganinėmis medžiagomis padengtomis geležies dalelėmis, reguliuojant sukimosi greitį ir magnetinio lauko intensyvumą. Esant didesniam sukimosi greičiui pagreitėja medžiagos pašalinimas iš apdirbimo zonos, paviršiaus šiurkštumas mažesnis esant mažesniam magnetinio lauko intensyvumui (Lee et al 2015 santrauka. Straipsnyje aprašomas optinių detalių poliravimo procesas, naudojamosios technologijos ir medžiagos.…”