Anant Kumar Singh

Magnetorheological Ball End Finishing Process

Finishing of three-dimensional (3D) surfaces such as grooves, projections, or complex in depth profiles on workpiece surfaces is a challenging task for the many existing advanced fine finishing processes. The advanced fine finishing processes have been developed to precisely control the abrading forces through external magnetic field. The applications of state-of-art finishing processes are limited to specific geometries only such as concave, convex, flat, and aspherical shapes due to restriction on relative movement of finishing medium and workpiece. Many of these processes are incapable of finishing of 3D intricate shaped surfaces. To overcome this problem, a new finishing process for flat as well as 3D surfaces using ball-end magnetorheological (MR) finishing tool is developed for ferromagnetic as well as non-ferromagnetic materials. The smart behavior of MRP fluid is utilized to precisely control the finishing forces and hence the final surface finish. A computer controlled experimental setup is designed and developed to study the process characteristics and performance. The magnetostatic simulations of flux density in MRP fluid between tool and workpiece has been done to visualize the finishing spot shape and size in contact with the workpiece surface. EN31 magnetic steel and nonmagnetic copper workpieces were finished using developed machine to validate the process concept.

Nanofinishing of Fused Silica Glass Using Ball-End Magnetorheological Finishing Tool

The surface finishing of fused silica in nanometer range and in obtaining defect-free surface is a challenge and in high demand because of its applications for transmitting high energy laser pulses. A novel nanofinishing process using ball-end Magnetorheological (MR) finishing tool was developed for finishing of flat as well as three-dimensional (3D) surfaces of ferromagnetic and non-ferromagnetic materials. In this process, a magnetically controlled ball end of smart MR polishing fluid is generated at the tip of the cylindrical tool, and it is guided to follow the surface to be finished through computer controlled three-axes motion. The process is automated and used for finishing precise components in manufacturing system. The smart behavior of MR-polishing fluid is utilized to precisely control the finishing forces which exhibit change in rheological behavior in the presence of external magnetic field. The finishing of fused silica glass was done using cerium oxide Cerox 1663 abrasive powder. The effect of finishing time on final surface roughness was studied, and the finished surfaces were observed under atomic force microscope. Significant improvement in surface roughness (Ra), root mean square (RMS), and Rmax value has been obtained after 90 min of finishing. Ra as low as 0.146 nm was achieved from initial value of 0.74 nm.

Performance Analysis of Ball End Magnetorheological Finishing Process with MR Polishing Fluid

A ball end magnetorheological finishing (BEMRF) process was developed for finishing a flat as well as 3D workpiece surfaces. The BEMRF process has a wide scope in todays advanced manufacturing systems for finishing 3D complex surfaces. Magnetorheological (MR) polishing fluid is used as finishing medium in BEMRF process. The constituent of MR polishing (MRP) fluid includes ferromagnetic carbonyl iron powder, abrasives, and base fluid medium. The workpiece surface is mainly finished by abrasives contained in MRP fluid. Therefore, the different mesh size from 400 to 1200 and volume percent concentration from 5% to 25% of abrasives in MRP fluid were chosen as factors to study their effects on the developed process performance in terms of percent change in roughness values. Silicon carbide abrasives were chosen in the present experimental investigation. Experiments were performed on the ferromagnetic ground surfaces whose initial roughness values (Ra) were measured in the range of 0.428 to 0.767 µm. The experimental results revealed that the MRP fluid with 15 vol % abrasives of mesh number 400 demonstrated better improvements in surface texture of finished surface as compared to other MRP fluid compositions. The finished surface characteristics and textures were studied at microscopic level using scanning electron microscopy and atomic force microscopy.

Magnetorheological methods for nanofinishing – a review

ABSTRACT 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 finishing method, the ball end magnetorheological finishing was developed and found more suitable method for finishing of 3D surfaces as its tool moves on surface similar to milling cutter tool during machining. The selection of finishing particles in magnetorheological method plays an important role for ultrafine finishing of new engineering materials.

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

ABSTRACT 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 surface roughness at the nanolevel and microscopic improvement on the die punch surface have demonstrated the feasibility of present finishing processes to be useful in industries for manufacturing the smooth surface of bottles’ plastic caps.

Development of magnetorheological finishing process for external cylindrical surfaces

ABSTRACT 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 manufacturing machine. The surface roughness values Ra, Rq, and Rz are reduced to 54.41%, 51.65%, and 40% with flat tool tip surface and 80.88%, 81.32%, and 82.5% with curved tool tip surface in 90 min of finishing time. The overall results reported that the present process with curved tool tip surface is comparatively more useful in finishing the external cylindrical surfaces.

Parametric analysis of an improved ball end magnetorheological finishing process

A novel surface finishing method using an improved ball end magnetorheological finishing tool was developed for nanofinishing of flat, as well as three-dimensional workpiece surfaces. An improved magnetorheological finishing tool is the main part of the present finishing process, which has been made up of the central rotating core and stationary electromagnet coil integrated with a copper cooling coil. A magnetically generated ball end finishing spot of magnetorheological polishing fluid was used as a finishing segment at the tip surface of the rotating core. In this research, detailed study through statistical design of the experiments was conducted for nanofinishing of ferromagnetic workpieces by the proposed ball end magnetorheological finishing process. Response surface methodology has been used to plan and analyze the effect of rotational speed of the tool core, magnetizing current and working gap on percentage change in surface roughness. The experimental results were discussed and the best finishing conditions were identified within the experimental range of variables. Analysis of experimental data showed that the percentage change in surface roughness was highly influenced by the working gap, followed by magnetizing current and rotational speed of the tool core. The best surface finish obtained on the ferromagnetic workpieces was as low as 27.6 nm from the initial value of 142.9 nm in 30 min of finishing time. In order to study the finished surface morphology, scanning electron microscopy and atomic force microscopy were also conducted.

A novel magnetorheological honing process for nano-finishing of variable cylindrical internal surfaces

ABSTRACT A novel magnetorheological honing process is designed and developed for nano-finishing of cylindrical internal surfaces with the help of permanent magnets. The radial movement of magnetic tool surface is adjusted as per the internal diameter of different cylindrical components and make it fixed before start of finishing so that it can maintain constant working gap while perform finishing. The present developed magnetic tool surface always constitutes higher magnetic field than the inner surface of ferromagnetic or non-ferromagnetic cylindrical workpiece. This is an important requirement to finish the internal surface of ferromagnetic or non-ferromagnetic cylindrical components because it ensures MR polishing fluid cannot stick on the workpiece surface while performing the finishing. Hence, present developed process is useful for finishing of ferromagnetic cylindrical molds, dies, hydraulic actuators, etc. for its better functional applications after the conventional honing or grinding process. The internal surface roughness of cylindrical ferromagnetic workpiece is dropped to 90 nm from its initial value of 360 nm in 100 minutes of finishing. Further scanning electron microscopy has also been done to understand the surface characteristics of finished workpiece. The results revealed that the developed magnetorheological honing process is capable to perform nano-finishing of internal surface of the ferromagnetic cylindrical components.

A new magnetorheological finishing process for ferromagnetic cylindrical honed surfaces

ABSTRACT 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 functional applications of ferromagnetic cylindrical honed surface after removing the various surface defects such as deeper grooves, honing grooves with shaper edges, torn and folded metals, and cavities or holes. The applications of new MR finishing process can also be useful in the internal finishing of injection barrel of a molding machine, cylindrical molds and dies, hydraulic cylinder, etc.

Analysis of particles in magnetorheological polishing fluid for finishing of ferromagnetic cylindrical workpiece

ABSTRACT Magnetorheological honing process is developed for nanofinishing of internal surfaces of ferromagnetic and non-ferromagnetic cylindrical objects. The process makes use of smart fluid called magnetorheological (MR) polishing fluid for finishing which has a property to become stiff in the existence of magnetic field. The smart MR polishing fluid is made with the ingredients of carbonyl iron (CI) particles, abrasive particles, and base fluid. Direct current given to the electromagnet coil engenders magnetic field on finishing tool surface. Magnetic force acts on magnetic CI particles which further exert the repulsive force on nonmagnetic silicon carbide (SiC) abrasive particles and performs finishing when tool rotates as well as reciprocates inside the cylindrical workpiece. The CI and SiC particles present in MR polishing fluid are magnetically simulated and analyzed using finite element (FE) analysis. The distribution of magnetic flux density and magnitude of magnetic force acting on CI particles are analyzed through FE analysis. It is found that the CI particles which are available adjacent to the active abrasives are major responsible for indenting the active abrasive particles into workpiece surface. Also, the effect of finishing tool surface areas and particles size on the strength of chains of CI particles in MR polishing fluid have been analyzed.