Modeling and simulation of surface roughness in magnetorheological fluid based honing process

Nano-finishing of a material surface is one of the most required properties in industry. There is high need of nano-finishing of diamagnetic materials such as copper and its alloys in electronic industries and electrode of electric discharge machining. Some industries like laser, aerospace, dentistry and metal optics etc. widely use highly finished copper mirrors. As copper is soft and chemically reactive material, its surface finishing at nano level is a difficult tasked. To fulfill this need, a new magnetorheological technique for precise surface finishing of diamagnetic materials has been conceptualized. Two cylindrical permanent magnets along with magnetorheological polishing fluid have been used to finish the diamagnetic copper alloy workpiece. The cylindrical permanent magnets tool with magnetorheological polishing fluid at its tip surface is rotated over the copper alloy workpiece surface and performs finishing by the stiffened magnetorheological polishing fluid. The permanent magnets finishing tool along with magnetorheological polishing fluid at its tip surface and diamagnetic copper workpiece have been modeled as well as simulated in Maxwell Ansoft V13 (student version) software. Distribution of magnetic flux density in the working gap is obtained and analyzed. Experiments are performed on the copper alloy workpiece and least Ra value of 28.8 nm is achieved in finishing time of 7.5 min from its initial value of 273.6 nm. Surface characteristics of both polished and unpolished workpiece are analyzed with the scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results obtained from finite element analysis and experimentation assures that the new design of magnetorheological finishing tool using permanent magnets is capable to nano-finish of diamagnetic materials such as copper alloy etc.

Magnetorheological nano-finishing of diamagnetic material using permanent magnets tool

The need of fine finishing of gears with high shape accuracy increases in various industrial, military and scientific instruments applications for enhancing the working performance, power transmission capability, service life, reliability as well as decreasing noise and vibrations at high speed. The surface asperities, dimensional inaccuracy, rough surface and shape inaccuracy of a gear tooth profile occur because of the high speed of material removal mechanism which leads to undesirable effect such as noise and vibration in the gearbox. Therefore, utilizing the conventional tool for finishing of gears at high material removal rates may increase inaccuracy in gear teeth profile shape due to the transverse grinding lines, burns, fine cracks, uneven stress, and thermal distortion. This paper reports on a novel design of a magnetorheological gear profile finishing (MRGPF) tool and its performance analysis to finish the gear teeth profile with more precisely and accurately. The MRGPF tool is made likely similar to the gear grinding profile wheel tool. To analyze the uniform finishing at the gear tooth profile, the magnetostatic finite element analysis (FEA) is performed to predict the uniform magnetic flux density at the proposed tool surface using Maxwell Ansoft. On the basis of the result obtained of magnetic flux density distribution on its finishing surface, the MRGPF tool is designed and fabricated. Further, the experiments are performed to examine the finishing performance of the newly designed tool on the EN-24 steel spur gear teeth profile. The results attest the significant improvement in finishing of gear teeth profile surface with high shape accuracy (DIN standard). This may result in improvement in scuffing performance, reducing noise and vibrations at high speed, reducing wear rate on gear teeth profile and also provides lower friction and temperature during its functional operation.

A novel magnetorheological gear profile finishing with high shape accuracy

The recent increase in demand for functional and technological requirements of the component results in the development of complex geometrical shapes and that too with close tolerances and fine surface quality. To fulfill the needs for finishing the external cylindrical surfaces such as groove, taper, step surfaces, and threads, an advanced finishing process based on magnetorheological (MR) fluid has been developed. The developed process can finish the external cylindrical surfaces with controlled magnetic field as likely similar to turning operation. Fine finishing of external cylindrical surfaces is a significant requirement in many functional applications. The wide applications of this present process can be valuable in automotive, machine tool production, valves manufacturing, and aerospace. A modified new MR finishing tool with flat and curved tip surface has been made to perform finishing on external cylindrical surfaces. The present cylindrical finished workpiece is useful in macaroni manuf...

Development of magnetorheological finishing process for external cylindrical surfaces

Various plastic products such as bottles’ plastic caps are manufactured through casting using permanent molds. To obtain the smooth surface on plastic caps during manufacturing, the required permanent mold die punch surface should be defect free and its roughness values in nanometer range. Two different magnetorheological (MR) fluid-based finishing processes are used for nano-surface-finishing of die punch. The MR ball end with solid rotating tool core is used to finish the flat surface, and a turning type MR finishing process is used for external circular surface of the present mold die punch. The material of the present permanent mold punch is P20 tool steel with hardness of 431 VHN. The final roughness values of flat and external circular surfaces of the present die punch are obtained as 30 nm and 80 nm from the initial values of 1080 nm and 630 nm in 120 min of finishing. The change in topography of the surface is observed using metallurgical microscope and mirror image test. The reduction in ...

Nano-surface-finishing of permanent mold punch using magnetorheological fluid-based finishing processes

The functional requirement of the components as well as safety and aesthetic compulsion make it necessary to improve the surface characteristics before putting it into the useful applications. Therefore, it is important to achieve superior surface finish very close to dimensional precision. Also, 3D components are being found more useful in today’s industries which lead to an increased demand for nanofinishing. This article mainly emphasizes on the analysis of magnetorheological methods suited for finishing of various surfaces. The surface is mainly finished by the abrasives hold within carbonyl iron particles chains in magnetorheological fluid during operation. The traditional finishing methods are comparatively less valuable in case of 3D surface finish due to lack of better controllable finishing force and constraint in tool movement. Magnetorheological methods were found to have better control over the forces and more flexibility in tool movement over various types of surfaces. Recently, a new...

Magnetorheological methods for nanofinishing – a review

In today’s industries, the internal surface finishing of cylindrical objects is highly demanded to improve their functional performance in various engineering applications. During the traditional honing operation, the finishing forces produced by abrasives on the workpiece surface are not easily controllable and also produce various surface defects. Therefore, to further improve the surface integrity of the traditionally cylindrical honed surface made of ferromagnetic or non-ferromagnetic materials, a new magnetorheological (MR) finishing process has been used with a controlled magnetic field. The experimentation is performed on the honed surface made of gray cast iron, which is generally used as a cylinder liner. The percentage change in surface roughness values, i.e., Ra, Rq and Rz, reduced by 77.44%, 70.16% and 72.16%, respectively, with better improvement in surface after 90 minutes of finishing. The experimental results demonstrated the effectiveness of present process for improving the funct...

A new magnetorheological finishing process for ferromagnetic cylindrical honed surfaces

A magnetorheological fluid-based process is developed for the internal surface finishing of ferromagnetic cylindrical workpiece. The existing finishing processes based on magnetorheological fluid a...

Development of magnetorheological fluid-based process for finishing of ferromagnetic cylindrical workpiece

The spot nanofinishing of surface plays an important role for improving the surface quality of miniature mechanical, electronics, and optics components. The nano-level finishing of these miniature components is highly demanded in today’s industry to fulfill the operational and functional requirement. The principal innovation of the present work is generating uniform magnetic field at the end of a magnetizable rotating core tool for providing a uniform surface roughness on a spot finishing of precision components. To fulfill this requirement, a ball nose magnetorheological nanofinishing process based on solid rotating core tool is developed. The existing ball end magnetorheological finishing (BEMRF) process uses a rotating core with central hole for flow of polishing fluid at the tool end surface. Due to central hole inside the rotating core, a non-uniform magnetic flux density has been experienced at the tool end surface which may result in non-uniform surface roughness in spot finishing, i.e., on a fixed location without any X-Y-axis linear feed rates. The magnetostatic finite element analysis clearly revealed the uniform magnetic flux density at the end surface of the solid rotating core tool than existing BEMRF tool core having central hole. The experimentation has been carried out for spot finishing on ferromagnetic workpiece surface in order to study the variation in surface roughness values. The present ball nose magnetorheological finishing process with solid rotating core tool produced uniform average surface roughness values as 20 nm from 290 nm after 90 min of spot finishing on the ferromagnetic workpiece surface. The experimental results confirmed the effectiveness of generating uniform magnetic field at the end of a magnetizable rotating core tool for a spot uniform nanofinishing of precision components.

Talwinder Singh Bedi

Papers

Magnetorheological methods for nanofinishing – a review

Modeling and simulation of surface roughness in magnetorheological fluid based honing process

A new magnetorheological finishing process for ferromagnetic cylindrical honed surfaces

Development of magnetorheological fluid-based process for finishing of ferromagnetic cylindrical workpiece

Spot nanofinishing using ball nose magnetorheological solid rotating core tool