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

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.     

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

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.     

Development of magnetorheological finishing process for external cylindrical surfaces

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.     

Improved magnetorheological honing process for nanofinishing of variable cylindrical internal surfaces

Improved magnetorheological honing process is developed for nanofinishing of variable cylindrical internal surfaces with better surface integrity. In the present work, finishing performance of existing magnetorheological honing process is enhanced. The present improved process consists magnetorheological honing tool having curved permanent magnet end surfaces. When magnetic field is analyzed using Ansoft Maxwell, the improved magnetorheological honing process results in uniform and higher magnitude of magnetic flux density over its magnetic tool curved end surfaces as compared to the tool having magnetic flat end surfaces. Therefore, an improved magnetorheological honing process has been developed with tool having curved permanent magnet end surfaces. During experimentation, surface roughness values Ra, Rq, and Rz get decreased by 76.28%, 76.67%, and 75.20%, respectively, with improved magnetorheological honing tool having curved end magnetic surfaces, while 47.97%, 46.24%, and 47.08% decreased with tool having flat end magnetic surfaces in same 60 minutes of finishing time. This results in enhancement of finishing performance of the present improved magnetorheological honing process in terms of reduced finishing time and ability to produce good surface integrity. Hence, the present improved magnetorheological honing process performance with tool having curved end magnetic surfaces is found as comparatively better than the finishing tool having flat end permanent magnetic surfaces.     

Numerical analysis and experimental validation of surface roughness and morphology in honing of Inconel 718 nickel-based superalloy

Honing is an important technology for machining onboard system parts. The parts are usually made of difficult-to-machining materials, e.g., Inconel 718 superalloy. Honing can improve the finishing accuracy and surface quality. However, the selection of the honing parameters was primarily based on the results of a large number of experiments. Therefore, the establishment of a reliable model is needed to predict the honed surface roughness and morphology, and offers a theoretical direction for the choice of parameters. In the present study, a numerical simulation model was constructed for analysis of the honing process by Python. The oilstone, workpiece surface morphology and motion trajectory were discretized by Python, and the machined surface was obtained by trajectory interference. Firstly, based on the statistical analysis of the surface topography of oilstone, the shape of grains was simplified and the surface topography of oilstone was built accordingly. Then, the initial surface morphology of the workpiece was constructed and the trajectory of grains on the workpiece surface was analyzed, which showed the distribution of the removed material. Meanwhile, the plastic deformation of material was analyzed in the simulation model. The critical depth of three stages of contact between grains and workpiece was calculated by the theoretical formula: scratching, ploughing and cutting. By analyzing the distribution of bulge, the plastic deformation in ploughing and cutting stage was studied. Further, the simulated results of honed surface roughness and morphology were validated and agreed reasonably well with the honing experiment. Finally, the effects of honing process parameters, including grain size, tangential speed, axial speed, radial speed and abrasive volume percentage, on the surface roughness of the workpiece were analyzed by the simulation model. The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00422-0     

Improved magnetorheological finishing process with rectangular core tip for external cylindrical surfaces

Finishing of the external surface of cylindrical components at nano-level using magnetorheological process has witnessed for rising demand in the manufacturing industries to improve its functional applications. In this paper, the best required shape of the tool core tip surface in the magnetorheological finishing process is attempted to design for improving the efficiency of the process on external cylindrical surfaces. The different shapes of the tool core tip surface are designed, and their performance was analysed with the help of magnetostatic finite element analysis. The design of a rectangular shaped tool core tip surface is found more effective for uniform and higher flux density. The experiments are conducted on the cylindrical external surface using the recently developed rectangular and existing circular shaped tool core tip surfaces. After the magnetorheological finishing with rectangular and circular shaped tool core tip surfaces, the final surface roughness values get reduced to 18 nm and 45 nm from the initial value of 310 nm. Surface waviness, characteristics and mirror images are also found better while magnetorheological finishing performed using the rectangular core tip surface. Hence, the rectangular shaped design of the tool core tip surface is found to be more useful in improving the effectiveness of the present process.     

The Comparative Appraisal of Quality Characteristics of Holes after Different Finishing Methods

Magnetic abrasive machining (MAM) of internal surfaces is a less studied process than machining of external surfaces. The present study contains MAM principles of round internal parts. The finishing method MAM forms optimum physical-mechanical properties of surface layer parts which are most relative to operation. The article contains comparative data of quality characteristics of parts from steel 45 and 12X2H4A after grinding, honing and MAM. It states the peculiarities of roughness formation of surface and its physical-mechanical characteristics after mentioning finishing methods.     

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 today's 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 (R_a) 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.     

多环形槽结构磁流变阻尼器的实验建模

对自行设计的、多环形槽结构磁流变阻尼器进行了理论分析与实验建模.该阻尼器的主要特点是在阻尼活塞周向表面上开有若干个矩形齿状环形槽,并且通过磁路设计,使流经阻尼通道处的磁流变液流动方向与其作用的磁力线方向垂直,用以增大阻尼力和阻尼力变化范围.然后从磁流变液的流变特性、电磁学的角度出发,利用修正了的非牛顿流体宾汉模型、结合实验数据,建立了该阻尼器的力学模型.利用该模型绘制和分析了外加磁场(通过施加电流实现)和阻尼力之间关系曲线,与实验结果较好吻合,从而证明了模型的正确性,为磁流变液阻尼器设计和性能预测提供了参考.     

Magnetorheological finishing of ferromagnetic blind-hole type surfaces

Products having blind-hole type surfaces such as bottle caps are being manufactured in today’s industry and are of great use. Such products are made in permanent blind-hole type mold cavities. At present, these cavities are being finished by internal grinding operations. After grinding, surface defects such as deep-seated groove, cavity, axial scratch, and ploughed material are induced because of uncontrollable finishing forces applied by grinding pins onto the workpiece surface. To obtain a better quality on final-made products, the blind-hole type mold cavities should be made defect-free. In the present process, two different tools based on magnetorheological fluid are developed to finish the lateral and bottom surfaces of cylindrical blind-hole type mold cavities. The workpiece used for finishing is the hardened EN31 die steel. The finite element studies determined the variation in magnetic field within the working gaps. The change in surface roughness (R_a) values of both inner lateral and bottom surfaces reduced by 67.7% and 69.5%, respectively, and found significant improvement in surface characteristics as compared to the initial grind surfaces. The results revealed the usefulness of present process to finish the blind-hole type mold cavities in manufacturing industries for producing a better quality of final-made products.     

Tribological properties of twin wire arc spray coated aluminum cylinder liner

The effects of honing process on the friction and wear behaviors of Twin Wire Arc Spray (TWAS) coated aluminum cylinder liners were investigated using a pin-on-reciprocating type of a tribotester. Two types of coated cylinder liners were prepared for the tests: Type I — smooth honing (SH) with ~ 40° honing angle, and Type II — helical structure honing (HSH) with ~ 140° honing angle. The aluminum cylinder liners were coated with an Fe0.8C wire by the TWAS process. In un-lubricated condition, Type II specimen showed lower coefficient of friction (COF) compared to Type I specimen. This result was due to the fact that the groove of Type II was sufficiently large to trap the wear particles that may otherwise contribute to three body abrasive wear. In lubricated condition, Type I showed lower COF due to its lower roughness in comparison to Type II. The experimental results indicate that TWAS process can be effectively utilized for engine applications in conjunction with optimum honing process for the cylinder liner.     

A rotating core-based magnetorheological nano-finishing process for external cylindrical surfaces

A rotating core-based magnetorheological finishing process has been developed to finish the external cylindrical surfaces at the nano-level more efficiently. The existing MR finishing process based on the stationary curved core tool tip is found to be comparatively less effective than the present process based on a rotating flat core tool tip for finishing the external cylindrical surfaces. This is due to the fact that in the present process both the workpiece and the tool rotating rather than giving rotation to the workpiece alone as in the existing process. The carbonyl iron particle (CIP) chains are rotated along with the rotation of the tool. This results in an increase in the kinetic energy of the active abrasive particles gripped by CIP chains which causes for the better finishing performance. Finishing is done by both the processes and their corresponding results are compared. The R_a, R_q, and R_z values are reduced to 71.62%, 72.53%, and 70.73% with a stationary curved core tool tip, and 94.59%, 94.51%, and 92.68% with a rotating flat core tool tip in 90 minutes of MR finishing. The overall results revealed that the present developed process using the rotating flat tool tip is more useful in finishing the external cylindrical surfaces as compared to the stationary curved tool tip.     

Study of superhydrophobic surface in self-cleaning of magnetorheological fluid

Magnetorheological (MR) fluid is a well-established controllable smart material for fabricating electromagnetic functional components and for magnetorheological finishing. However, the water and labor consumption in cleaning work could seriously reduce its efficiency. Superhydrophobic surface has been widely used in self-cleaning applications owing to its excellent anti-wetting property. In this work, superhydrophobic surface was adopted to prevent the microparticles from adhering to the solid surface, in order to realize the easy washing of MR fluid. The superhydrophobic surface showed water-repellency when MR fluid contact angles exceeded 150°. The bouncing phenomena of the MR fluid were observed even though the carbonyl iron powders concentration was up to 70 vol%. Additionally, the mechanical durability and robustness of prepared surface were satisfactory during the sandpaper polishing process and MR fluid wear tests. Moreover, excellent self-cleaning properties can be obtained by changing micropowders scale from millimeter to nanometer and MR fluid—a complex suspension system. The superhydrophobic surface is expected to be an adaptable and efficient method for reducing human labor and saving water during the cleaning of MR fluid, and may have potential of applications in the precise analysis of complex suspensions.     

Finishing of Hardened Boreholes: Grinding or Hard Cutting?

The finishing processes of parts have been carried out mainly by abrasive grinding techniques. Grinding is a theoretically well-elaborated and widespread machining process. That is why its replacement by another metal removal technique, hard cutting, requires very careful examination. In this article, the possibilities are outlined for finishing internal cylindrical surfaces of hardened steels (i.e., boreholes, by employing hard cutting instead of grinding). The process characteristics, the surface quality, and some economic and ecological features of the process are compared theoretically and experimentally, and discussed.     

Response of acoustic imaging systems using convergent leaky waves to cylindrical flaws

A theoretical study of imaging systems utilizing focused leaky surface acoustic waves (SAWs), and their response to certain kind of defects is presented. In particular, circular cylindrical inhomogeneities with axes perpendicular to the surface are considered. The scattering of the SAW from this cylinder is formulated with some approximations. The surface wave incident on the inhomogeneity is initially found as an angular spectrum of plane waves. However, to apply the boundary conditions at the cylindrical surface, the incident field has to be transformed into a superposition of cylindrical waves. Similarly, the scattered field, which is found in the form of outgoing cylindrical SAWs, is converted back to a plane wave spectrum. A formula is obtained for the transducer output voltage in terms of the position and the radius of the cylinder, and it is suitable for computer evaluation. By considering various locations for the cylinder, the sensitivity of the system around the focal point is studied. By comparing the output voltages for cylinders of different radii, the sensitivity of the system to the size of the inhomogeneity is examined. The numerical results are in agreement with the experimental observations.     

Investigations on the Effect of Ball Burnishing Parameters on Surface Hardness and Wear Resistance of HSLA Dual-Phase Steels

Surface finish has a vital influence on most functional properties of a component like fatigue life, wear resistance, corrosion resistance, etc. This has given birth to processes such as lapping, honing, burnishing, etc. Burnishing is a fine finishing operation involving the cold working plastic deformation of surface layers to enhance the surface integrity and the functional utility of a component. The present study has been carried out to establish the effect of burnishing parameters viz. feed rate, speed, force, ball diameter and lubricant on surface hardness, and wear resistance of HSLA dual-phase steel specimens. The result indicates that burnishing parameters have significant effect on the surface hardness and wear resistance.     

Development of a surface defect inspection system using radiantlight from steel products in a hot rolling line

The steel industry is constantly trying to reduce production cost and improve quality by making the steel manufacturing processes continuous and faster. Currently, the rolling process of steel production is largely automated, while the finishing process is not yet appreciably automated. The finishing processes involve many tasks difficult to automate, such as defect inspection and repairing the detected defects. In recent years, however, many automated and labor-saving systems have been developed for use in the finishing processes. The surface defect inspection of steel products is the largest bottleneck in the finishing process. This paper describes an inspection system of steel surface defects for large sections, such as wide flange beams and I-beams. This system is based on applied radiant light and it senses the temperature deviation caused by defects. The wavelength of the detector is optimized to improve the signal-to-noise ratio. An optical attenuator was developed to compensate for the known temperature distribution across the product immediately after rolling. The image processor takes only 50 ms per image frame. Each time frame has the necessary image information to detect defects     

Magnetorheological nanofinishing of BK7 glass for lens manufacturing

BK7 is a high-quality crown glass which is used where additional benefits such as temperature sensitive applications of fused silica glass are not required. Due to very low inclusion content with extremely low bubbles, BK7 glass can find its application in lens manufacturing. The present work focuses on nanofinishing of the BK7 glass specimen for ratifying its utility in practical application. A programmable logic controlled 3-axis motions are fed to the magnetorheological (MR) rotating tool for finishing the glass specimen. MR polishing fluid used for nanofinishing consists of deionized water, magnetic iron particles, and cerium oxide powder. Under the influence of magnetic field, the stiffened MR polishing fluid is assisted in reducing the surface roughness of glass up to nanolevel range. Optical properties such as transmittance, absorbance, and reflectance of finished BK7 glass are analyzed and found suitable for lens manufacturing. Results of higher surface quality with excellent finishing are obtained by the present MR finishing process. After 90?min of finishing, the surface roughness values R_a and R_q are reduced to 17 and 27?nm from the initial values of 41 and 57?nm, respectively. To study the surface morphology, scanning electron microscopy is performed on BK7 glass.     

Effect of applied voltage and electrolyte parameters on pitch,runout, flank topology,and finishing productivity of the straight bevel gears in PECH process

This paper describes improvements in the considered parameters of micro-geometry: flank surface topology and finishing productivity of 20MnCr5 alloy steel straight bevel gears through their finishing by pulsed electrochemical honing (PECH) process. Effects of three most important parameters of PECH process, namely applied voltage, electrolyte composition, and electrolyte concentration were investigated to identify their optimum values. Pre-identified values of other PECH parameters and an aqueous mixture of NaCl and NaNO₃ as an electrolyte were used in the present work. Errors in pitch (i.e., single pitch error, adjacent pitch error, and cumulative pitch error) and runout were used to evaluate micro-geometry of the straight bevel gears while volumetric material removal rate was used to judge the finishing productivity of the PECH process. Topology of the gear tooth flank surface and microstructure of the best-finished bevel gears were also studied. The results revealed considerable improvements in the micro-geometry, flank surface topology, and microstructure of the bevel gears finished by PECH. Applied voltage of 8?V, electrolyte composition of 75?wt.% NaCl?+?25?wt.% NaNO_3, and electrolyte concentration of 7.5?wt.% were identified as the optimum values to achieve simultaneous improvement in all the considered responses.     

Synthesis of polishing fluid and novel approach for nanofinishing of copper using ball-end magnetorheological finishing process

Ball-end magnetorheological (MR) finishing process utilizes the magnetically controlled stiffened ball of an MR fluid for finishing purposes. Copper is a mechanically soft and chemically reactive material, so it is difficult to finish up to the nanometer-order level by traditional and most of the advanced finishing processes. In this research work, the problems associated with ball-end MR finishing of copper have been explored and a fluid composition suitable for the finishing of copper has been developed. A novel approach using two opposite magnetic poles has been used to enhance the magnetic flux density distribution between the tool tip and the copper workpiece surface. The same has been magnetically simulated and verified experimentally. The effect of fluid composition parameters has been analyzed by the statistical model developed by response surface. After 30 minutes of finishing time, a nano-finished surface with very few shallow scratches was achieved.