Calculation of MRF influence functions

Schinhaerl, Markus; Smith, Gordon; Geiss, Andreas; Smith, Lyndon; Rascher, Rolf; Sperber, Peter; Pitschke, Elmar; Stamp, Richard

doi:10.1117/12.730806

Cited by 8 publications

(5 citation statements)

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“…Abrasive particles indent into the workpiece surface at a given normal force. The calculation of the indentation diameter and depth becomes important to calculate indentation volume There are some assumptions made before using equations ( 13) and (14). Abrasive particles have a spherical shape of average diameter (D g ) and they all have same size, OFHC copper is a perfectly plastic material, there is no velocity parallel to the surface of workpiece, load on each abrasives is assumed to be constant which creates same depth of penetration on the workpiece surface.…”

Section: Resultsmentioning

confidence: 99%

“…Indentation depth increased with volumetric removal rate (VRR), but there was no effect on the VRR on changing the magnetic field strength. Schinhaerl et al [14] developed a software tool for fast determination of MRF influence function. The fluid properties, lens parameters, and magnetic field strength were varied to investigate peak removal and volume of the influence function.…”

Section: Introductionmentioning

confidence: 99%

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Numerical and experimental study of influence function in magnetorheological finishing of oxygen-free high conductivity (OFHC) copper

Dubey

Sidpara

2020

Smart Mater. Struct.

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Study of influence function of finishing process is very important for setting the process parameters. In this article, influence function of magnetorheological finishing (MRF) process is investigated numerically and experimentally by studying the flow behaviour of magnetorheological (MR) fluid. A 3D computational fluid dynamics simulation is performed considering MR fluid as a Herschel-Bulkley fluid. Dynamic pressure and wall shear stress on the workpiece surface are determined for different working gaps and rotational speeds. Variable depth of indentation by abrasive particle on oxygen-free high conductivity copper is calculated numerically and correlated with the experiments. Depth and area of influence function increase with spindle speed and reducing working gap. Dynamic pressure decides the indentation depth which is related to normal force, whereas wall shear stress removes the material up to the indentation depth which is related to the tangential force. Influence function shows two separate regions at the edge of magnet due to variable magnetic flux density. Contact length of MR fluid with workpiece and squeezing of MR fluid play significant role in material removal. Experiments are carried out to study forces acting on the workpiece, indentation depth and validation of simulation results.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Numerical and experimental study of influence function in magnetorheological finishing of oxygen-free high conductivity (OFHC) copper

Dubey

Sidpara

2020

Smart Mater. Struct.

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“…[63][64][65] The model replaces the present trial-and-error method of determining an influence function. The model obviates the need to physically test the material removal on a sample workpiece surface and thus neither a sample workpiece nor a previous and subsequent measurement is required.…”

Section: Mathematical Influence Function Modelmentioning

confidence: 99%

Advanced techniques for computer-controlled polishing

et al. 2008

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Computer-controlled polishing has introduced determinism into the finishing of high-quality surfaces, for example those used as optical interfaces. Computer-controlled polishing may overcome many of the disadvantages of traditional polishing techniques. The polishing procedure is computed in terms of the surface error-profile and the material removal characteristic of the polishing tool, the influence function. Determinism and predictability not only enable more economical manufacture but also facilitate considerably increased processing accuracy. However, there are several disadvantages that serve to limit the capabilities of computer-controlled polishing, many of these are considered to be issues associated with determination of the influence function. Magnetorheological finishing has been investigated and various new techniques and approaches that dramatically enhance the potential as well as the economics of computer-controlled polishing have been developed and verified experimentally. Recent developments and advancements in computer-controlled polishing are discussed. The generic results of this research may be used in a wide variety of alternative applications in which controlled material removal is employed to achieve a desired surface specification, ranging from surface treatment processes in technical disciplines, to manipulation of biological surface textures in medical technologies.

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“…Due to the motion of the polishing tool, the whole workpiece may be polished. High-precision surfaces are achieved by varying the dwell time of the polishing tool on the workpiece surface [5]. The removal capability characteristic of MRF process can be described by a removal function (or "spot", see Figure 2), which is defined as the distribution of the total amount of the material removed per unit time.…”

Section: Principle Of Mrfmentioning

confidence: 99%

Dwell time algorithm based on the optimization theory for magnetorheological finishing

Zhang

Wang

et al. 2010

SPIE Proceedings

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Magnetorheological finishing (MRF) is an advanced polishing technique capable of rapidly converging to the required surface figure. This process can deterministically control the amount of the material removed by varying a time to dwell at each particular position on the workpiece surface. The dwell time algorithm is one of the most important key techniques of the MRF. A dwell time algorithm based on the 1 matrix equation and optimization theory was presented in this paper. The conventional mathematical model of the dwell time was transferred to a matrix equation containing initial surface error, removal function and dwell time function. The dwell time to be calculated was just the solution to the large, sparse matrix equation. A new mathematical model of the dwell time based on the optimization theory was established, which aims to minimize the 2-norm or ∞-norm of the residual surface error. The solution meets almost all the requirements of precise computer numerical control (CNC) without any need for extra data processing, because this optimization model has taken some polishing condition as the constraints. Practical approaches to finding a minimal least-squares solution and a minimal maximum solution are also discussed in this paper. Simulations have shown that the proposed algorithm is numerically robust and reliable. With this algorithm an experiment has been performed on the MRF machine developed by ourselves. After 4.7 minutes' polishing, the figure error of a flat workpiece with a 50 mm diameter is improved by PV from 0.191λ(λ = 632.8 nm) to 0.087λ and RMS 0.041λ to 0.010λ. This algorithm can be constructed to polish workpieces of all shapes including flats, spheres, aspheres, and prisms, and it is capable of improving the polishing figures dramatically.

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Calculation of MRF influence functions

Cited by 8 publications

References 0 publications

Numerical and experimental study of influence function in magnetorheological finishing of oxygen-free high conductivity (OFHC) copper

Numerical and experimental study of influence function in magnetorheological finishing of oxygen-free high conductivity (OFHC) copper

Advanced techniques for computer-controlled polishing

Dwell time algorithm based on the optimization theory for magnetorheological finishing

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