Abrasive Concentration Research Articles

Study on rheological properties and polishing performance of viscoelastic material for dilatancy pad

Shear dilatancy polishing (SDP) is an emerging flat polishing method for hard and brittle materials, which can achieve high-efficiency and high-precision polishing of workpieces under high-pressure and high-speed conditions. In our research, a novel viscoelastic material (VM) with non-Newtonian fluid properties was prepared. The dilatancy pad was subsequently obtained based on VM, abrasives, and a polyurethane pad. The effects of abrasive size and abrasive concentration on the rheological properties of VM were analyzed. The mechanism of abrasives in VM was investigated, and the principle of SDP was revealed. VM-30 wt%Diamond (0.5 μm) with excellent shear hardening performance was selected in the polishing experiment to study the effects of polishing time, polishing speed, and polishing pressure on polishing performance, and the optimal polishing parameters of SDP for tungsten were determined. Compared with traditional abrasive free polishing (AFP), SDP can realize a higher material removal rate (MRR increased by 33.4%) and better surface quality (Sa reduced by 32.2%) due to the shear dilatancy effect under high-pressure and high-speed conditions. After 90 min of SDP, the surface roughness (Sa) of tungsten workpiece was reduced from 307.9 nm to 12.1 nm. Results show that SDP is a promising and feasible polishing method for hard and brittle materials.

Study on Wear Mechanism of Helical Gear by Three-Body Abrasive Based on Impact Load.

This study aimed to explore the wear characteristics and evolution mechanisms of large-scale wind power gears under the impact load of particles of the three-body abrasive Al2O3 (0.2 mg/mL) from four aspects: oil analysis, vibration analysis, amount of gear wear, and tooth-surface-wear profile analysis. A magnetic powder brake was used to simulate the actual working conditions. Combined with the abrasive particle monitoring and the morphology analysis of the tooth-surface-wear scar, by setting quantitative hard particles in the lubricating oil, the gears are mainly operated in the abrasive wear state, and wear monitoring and wear degree analysis are carried out for the whole life cycle of the gears. Oil samples were observed and qualitatively analyzed using a particle counter, a single ferrograph, a metallographic microscope, and a scanning electron microscope. The experiments demonstrate that the initial hard particles have a greater impact in the early wear stage of the gears (<20 h), and abrasive particle concentration increases by 30%. This means that Al2O3 particles accelerate the gear wear during the running-in period. The loading method of the impact load on the oblique gear exacerbates the abrasion particle wear and expands the stress concentration, which reduces the surface of large milling particles on the surface, and reduces the width of the tooth (the part above the pitch line is severely worn), which causes the gear to break into failure. The research provides help for analyzing the mechanism of abrasive wear of gears and predicting wear life.

Highest Quality and Repeatability for Single Wafer 150mm SiC CMP Designed for High Volume Manufacturing

Silicon Carbide (SiC) provides excellent characteristics such as superior thermal conductivity, high carrier mobility and extreme chemical stability in comparison with those of Silicon (Si). SiC is already showing significant device performance benefits in power devices, high performance communication, and LED lighting. However, SiC presents many challenges for wafer surface treatment because of its high hardness and remarkable chemical inertness. Today, mechanical polishing techniques on industrial batch CMP tools are the predominant methods for SiC wafer surface treatment, but material removal rate (MRR), surface defects and wafer flatness control are reaching fundamental limits with increasing wafer diameter. Batch processing typically results in a higher amount of surface scratches and defects, higher wafer to wafer variability, and higher wafer breakage rates. A unique single wafer chemical mechanical polishing (CMP) technique on 150mm n-doped, 4° off-axis, single crystal, 4H-SiC wafers was developed to create a virtually defect-free surface. A polishing head has been designed to manipulate polishing pressures at various zones of the wafer. This capability can modulate the removal thickness at each region on the wafer surface, resulting in a highly uniform wafer profile. Additionally, a CMP slurry has been formulated to maximize MRR from 2μm/hr to over 8.5μm/hr. Potassium permanganate has been selected as an oxidant and aluminum oxide particles as the abrasive. The oxidant concentration and abrasive content along with slurry pH level have also been optimized for ideal chemical and mechanical activity. Scratch-free wafer surfaces are observed with atomic force microscopy (AFM) and bright field (BF) and dark field (DF) inspection techniques. Roughness on the Si face is reduced to below 0.08nm. Total length of surface scratches was reduced to 10mm or less. Industrial metrics of wafer flatness, including total thickness variation (TTV) and local thickness variation (LTV) are modulated and improved. A test run completed on 25-wafers shows an overall 31% improvement of TTV post CMP process.

Evaluation of Wear Measurement with Radioactive Isotopes for DLC Coatings Affected by Abrasive Particles

Diamond-like carbon (DLC) coatings protect engine parts from wear and provide low-friction. Unfortunately, the nature of DLC coatings does not allow progressing wear measurement using conventional methods. Therefore, we applied a radioactive isotope-based wear measurement method (RIC method). A tribometer with oscillating contact and one with sliding contact were used to provide different loading conditions. The RIC method was evaluated for DLC coatings, and the DLC wear was investigated regarding the presence of abrasive particles. The results indicate that an increase in abrasive particle concentration leads to an increase of DLC wear rate and a decrease in usage-time until wear-off.

Towards an Understanding of Multiphase Fluid Dynamics of a Microfluid Jet Polishing Process: A Numerical Analysis

The microfluid jet polishing (MFJP) process is a manufacturing technology in which small abrasive particles (such as diamond, alumina, and ceria) are premixed with a carrier fluid (typically water) to form a liquid suspension that is pressurized and expelled through a nozzle for material removal. The resulting microjet beam—with a typical nozzle exit diameter in the range from 0.1 to 1.0 mm—impinges the workpiece surface for material removal by erosion and/or abrasion and produces an ultraprecision surface. This work applies a computational fluid dynamics (CFD) model to analyze the key phenomena in the interaction of the liquid suspension and the workpiece surface. The liquid film characteristics (film height, minimum film height, positions of the minimum film height, and hydraulic jump) obtained from the CFD simulations are compared with the results derived from empirical formulations found in the literature. Subsequently, the numerical results are utilized to investigate the impact velocity, pressure distribution, and shear stress caused by the suspension on the workpiece surface. It is observed that the shear stress strongly depends on the injection pressure of the liquid suspension and is weakly dependent on the abrasive suspension concentration (the liquid suspension with different densities, viscosities, and surface tensions). Additionally, the particle behavior is investigated in order to estimate the impact velocity and to identify the impact and erosion zones of the liquid suspension on the workpiece surface. Numerical results indicate that ~50% of total particles are impinging the workpiece surface almost perpendicularly (with a mean impact angle of ~86 degrees) for the first time in the stagnation region, where they are strongly decelerated by the carrier fluid before they reach the workpiece surface. These particles, however, rebound on the surface and are reaccelerated by the carrier fluid, impinging the workpiece surface further in the radial direction.

Hand and Abrasive Flow Polished Tungsten Carbide Die: Optimization of Surface Roughness, Polishing Time and Comparative Analysis in Wire Drawing.

This research work highlights the benefits of abrasive flow polishing (AFP) applied to tungsten carbide dies compared with conventional hand polishing (HP). An indigenous experimental set-up for AFP was developed. The effect of prominent process parameters viz. extrusion pressure, number of cycles, and abrasive particle concentration on the final surface roughness, percentage improvement in surface roughness, and polishing time was investigated by Taguchi-designed experiments. The multi-objective optimization (MOO) was performed using the Taguchi-TOPSIS-Equal weight approach to find the respective optimized AFP parametric settings. A set of skilled operators performed the conventional HP of dies, and the best hand-polished (HPed) die was selected using the TOPSIS technique. The operational performance of the HPed dies and the abrasive flow polished (AFPed) dies were compared on the three-stage wire drawing operation. The results revealed that AFP’s surface resulted in a better-quality surface than hand polishing with a 27.06% improvement in surface roughness. Furthermore, AFP can reduce the dependency on costly and tricky-to-locate skilled operators, with a reasonable amount of time saving (about 87.05%). Overall, the study’s findings show that abrasive flow polishing of dies is fast and cost-effective.

Multi-Objective Optimization of Material Removal Rate and Tool Wear in Rough Honing Processes

This study focuses on obtaining regression models for material removal rate and tool wear in rough honing processes. For this purpose, experimental tests were carried out according to a central composite design of experiments. Five different parameters were varied: grain size or particle size of abrasive, density of abrasive or abrasive concentration, pressure of the stones against the cylinder internal surface, tangential speed (in this case, corresponding to the rotation speed of the cylinder), and linear speed of the honing head. In addition, multi-objective optimization was carried out with the aim of maximizing the material removal rate and minimizing tool wear. The results show that, within the range studied, the material removal rate depends mainly on tangential speed, followed by grain size and pressure. Tool wear is directly influenced by density of abrasive, followed by pressure, tangential speed, and grain size. According to the multi-objective optimization, if the two responses are given the same importance, it is recommended that high grain size, high density, high tangential speed, and low pressure be selected. Linear speed has less influence on both responses studied. If the material removal rate is considered to be more preponderant than tool wear, then the same values should be considered, except for high pressure. If tool wear is preponderant, then lower grain size of 128 (ISO 6106) should be selected, and lower tangential speed of approximately 166 min−1. The other variables, density and pressure, would not change significantly from the first situation.

Research on quality control of precision machining straight internal gear by abrasive flow based on large eddy simulation

Traditional finishing technology is difficult to realize the precision machining of complex geometric parts. Abrasive flow machining technology solves this problem well. Taking the spur internal gear as the research object, the wall shear force, static pressure, dynamic pressure, and abrasive velocity vector of the internal channel of the straight internal gear under different inlet velocity, abrasive concentration, and abrasive particle size are analyzed by using the large eddy simulation method, and the action law of different parameters on the machining of straight internal gear by solid–liquid two-phase abrasive flow is discussed. At the same time, the orthogonal test was carried out. The results show that the solid–liquid two-phase abrasive flow machining technology can effectively remove the burrs, pits, and bulges on the tooth surface of spur internal gear, reduce the tooth surface roughness, and improve the surface quality. The optimal combination of processing parameters and the primary and secondary order of various factors affecting processing are obtained by range analysis and analysis of variance. The regression equation is constructed by regression analysis to verify the effectiveness and accuracy of the model, which provides theoretical support and data reference for actual processing and production.

Characterization of finished surface through thermal additive centrifugal abrasive flow machining for better surface integrity

Abrasive Flow Machining (AFM) process has been a useful technique for deburring and polishing of the surface and edges through the abrasive laden media. The surface material has been removed in form of micro chips due to abrasion action of sharp cutting edges abrasive particles. A large amount of force and energy has been lost due to frictional forces between the surface and abrasive particles in AFM process. A new hybrid form of AFM process named as thermal additive centrifugal abrasive flow machining (TACAFM) has been discussed in the present investigation, which utilized the spark energy to melt the surface material. A lesser amount of force has been required by the abrasive particles to remove the molten material from the surface and also minimized the energy loss. In the present investigation central composite design response surface methodology has been used to plan and conduct the experiments using Design Expert® 11 software. Experiments have been performed to analyze the effect of input process variables such as current intensity, duty cycle, abrasive concentration, rotational speed of the electrode and extrusion pressure on scatter of surface roughness, micro hardness and % improvement in Ra of the workpiece. Also the finished surface of the brass work piece has been characterized for the microstructure study using SEM and XRD analysis. From the experimental results it has been found that duty cycle has the most significant effect towards Scatter of surface roughness with a contribution of 17.5 % while current has been contributed largest as 85.17 % towards micro hardness. Also it has been observed that current has contributed largest as 21.88% against the % improvement in Ra. The optimum scatter of surface roughness, micro hardness and % improvement in Ra has been observed as 0.15 µm, 345.95 HV and 39.52 % respectively.

Formulations of desensitizing toothpastes for dentin hypersensitivity: a scoping review.

Objective:This study aimed to review evidence from randomized controlled trials (RCTs) to describe: 1) the active ingredients and desensitizing toothpaste brands; 2) the evaluation of these active ingredients over time, and 3) the fluoride and abrasive content in the formulations designed to treat dentin hypersensitivity (DH).Methodology:In total, 138 RCTs and their tested toothpastes were included. Searches were updated up to August 19, 2021. Formulations, reported brands, active ingredients over time, and type of fluoride (ionizable or ionic fluoride) and abrasive (calcium or silica-based) were analyzed (PROSPERO #CRD42018086815).Results:Our trials assessed 368 toothpaste formulations, including 34 placebo (9%), 98 control toothpastes with fluoride (27%), and 236 (64%) with active ingredients to treat DH. We tested the following active ingredients: potassium compounds (n=68, 19%), calcium sodium phosphosilicate (CSP) (n=37, 10%), strontium compounds (n=28, 8%), arginine (n=29, 8%), stannous fluoride (SnF2) (n=21, 6%), hydroxyapatite (n=9, 2%), potassium combined with another active ingredient (n=19, 5%), inorganic salt compounds (n=11, 3%), citrate (n=5, 1%), formaldehyde (n=3, 1%), herbal (n=4, 1%), copolymer (n=1, 0.5%), and trichlorophosphate (TCP) (n=1, 0.5%). The number of toothpaste formulations increased since 1968, with the greatest increment after 2010. Most toothpastes described their type of fluoride as sodium monofluorphosphate (MFP) (n=105, 29%) and NaF (n=82, 22%), with silica-based (n=84, 23%) and calcium-based (n=64, 17%) abrasives.Conclusion:Patients and dentists enjoy an increasing number of brands and active ingredients to decide what desensitizing toothpaste to use. The most common types of fluoride are MFP and NaF.

Optimization of process parameters in ultrasonic machining using integrated AHP-TOPSIS method

The process by virtue of which holes and cavities are formed in a metal work piece with the help of shaped tools, high frequency mechanical motion and abrasive slurry is known as Ultrasonic Machining Process. Its working principle is completely different from the other traditional machining processes such as laser beam machining and electrical discharge devices. This is developed machine removal processes in which the work material is less damaged by the thermal energy and it also introduce significant level of residual stress which is important for survival of the work material. This character of the process makes USM more enhanced and better machine job characteristics. This characteristic is also required for determining the optimal control parameter settings of an USM process’s is a non-traditional machining process in which abrasive content in slurry are driven against work by tool oscillating at low amplitude and high frequency. In this research paper stainless steel is used as tool material in the whole process and zirconia bio ceramic plate is taken as a work piece material. The process parameters are considered as feed rate, slurry concentration, power rating and grit size. Through this work, it is found that responses highly correlated with correlation coefficient, which justifies the application of MCDM as an optimization tool. The optimization studies are carried out on an ultrasonic machining process with multi response characteristics depend on the multi criteria decision making methodology (MCDM), using technique for order preference by similarity to ideal solution (AHP-TOPSIS) approach are described in this paper. The final results of this paper indicate the effectiveness of USM using MCDM method for different USM parameters to produce high quality parts made of zirconia Bio-ceramics with excellent productivity.

Effect of optimum process parameters in rotational-magnetorheological poppet valve polishing

ABSTRACT Poppet valves are commonly used as relief valves, pressure regulators, selectors, and inlet and exhaust valves in automobile internal combustion (IC) engines. Nanofinishing of ridge profiles of the poppet valve is a challenging task due to its narrowness. This article presents the precise finishing of narrow ridge profiles of poppet valves at optimum process parameters in the rotational-magnetorheological fluid-based finishing (R-MRFF) process using a novel magnet fixture. Statistical analysis is used to determine the impact of each process parameter. Further, simulation of finishing forces in the R-MRFF process is performed using software that applies the finite element technique. Investigation of finishing forces assists in controlling the process precisely. An analytical model is formulated for calculating the number of abrasive particles acting on nickel–aluminum–bronze alloy poppet profiles to anticipate final material dislodgement. The significant process parameters for surface roughness are abrasive volume concentration, poppet rpm, poppet vertical feed rate, and carbonyl iron particle (CIP) volume concentration. The minimum obtained surface roughness (Ra) at poppet valve profiles is 23.5 nm. The final finished poppet valve may have a longer service life and improved wear and corrosion resistance at maximum temperature and pressure.

РЕЗУЛЬТАТЫ СТЕНДОВЫХ ИСПЫТАНИЙ ПЛУНЖЕРНЫХ ПАР ВОССТАНОВЛЕНЫХ С ПРИМЕНЕНИЕМ НАНОКОМПОЗИЦИОННОГО ХРОМИРОВАНИЯ

The article presents the results of bench tests of serially manufactured plunger pairs of high-pressure fuel pumps (fuel injection pumps) of YAMZ-238ND3 diesel, restored using existing technology with the use of chromium-based electroplating and restored using the proposed technology with the use of chromium-based nanocomposition electroplating. The studies were conducted according to the OST 23.1-364-81 on mass-produced plunger pairs, plunger pairs restored according to the standard technology of restoration at repair enterprises and plunger pairs restored according to the proposed technology in the laboratory of applying hardening coatings of the Saratov State Agrarian University named after N. I. Vavilov. The method of bench accelerated wear tests implied the addition of abrasive particles to diesel fuel. The abrasive material consisted of quartz particles with dimensions of 3...5 microns at an abrasive concentration of 0.015 g/kg. The tests were carried out using the stand KI-22205-01 GOSNITI at the number of revolutions of the cam shaft 830 min-1. The test time was 130 hours. Every 10 hours, the starting cycle fuel supply was recorded on the reference fuel pump, which did not participate in the testing process. After the tests, the plunger pairs were checked for water tightness using the installation of the KI-759 model. The limiting value limiting the operability of the plunger pairs of the YAMZ-238ND3 injection pump was the starting cyclic fuel supply, which should not be lower than 180 mm3/cycle. As a result of the tests, it was found that all the tested fuel injection pumps did not reach the limit state. At the end of the tests, the cyclic starting supply of plunger pairs restored by nanocomposition galvanic chrome plating decreased by an average of 7.6%; restored by base chrome plating – by an average of 10.5%; serial – by an average of 13.8%. The hydraulic density of plunger pairs restored by nanocomposition galvanic chrome plating averaged 18 s, restored by base galvanic chrome plating – 16 with, serial – 15 s.

Control strategy of machining efficiency and accuracy in weak-chemical-coordinated-thickening polishing (WCCTP) process on spherical curved 9Cr18 components

To improve the machining efficiency and surface accuracy of curved parts, a new approach called Weak-Chemical-Coordinated-Thickening Polishing (WCCTP) concept is proposed for ultraprecision manufacturing of the key work surfaces of a spherical plain bearing in this paper. A specific WCCTP slurry (WCCTPs) is successfully prepared to achieve two capabilities: one is the shear-thickening rheology to form flowing abrasive-polymer-clusters with flexible shearing material removal with tribo-microcutting, the other is weak chemical-coordinated interaction to soften the worksurface with enhancing surface accuracy. High viscosity easily produces an effect on the excessive aggregation of abrasive-polymer-clusters, resulting in blockage called a jamming phenomenon. The peaks of each surface in the contacting zone are polished from the work substrate during these shearing actions of the “flowing abrasive tool”. In view of the principle of liquid thickening dynamics and chemical mechanism, a predictive mathematical model of material processing in WCCTP is established to guide the actual production. Under the condition of the verification experiment, the maximum deviation of this predicting equation can be controlled at about 8.03%, which demonstrates the effectiveness of our proposed WCCTP process. The effects of shearing velocity, abrasive concentration, abrasive size, weak chemical-coordinated interaction, polishing temperature, and gap depth are investigated in detail to illustrate the application of WCCTP on machining efficiency and surface accuracy. Moreover, the optimization applied to the actual experiment result indicates that our proposed WCCTP approach can implement the ultraprecision polishing for the spherical plain bearing of Sϕ 56.6 mm, and develop an ultra-smooth mirror with the roughness of Ra 25 nm, the roundness error of 4.0 μm, and high shape accuracy (=PV 1.16 μm). This work indicates that the WCCTP approach is a progressing ultraprecision machining on spherical curved 9Cr18 parts.

Preparation and processing properties of magnetically controlled abrasive solidification orientation—solid-phase Fenton reaction lapping-polishing plate for single-crystal 4H-SiC

To improve the ultraprecision processing efficiency and surface quality of single-crystal 4H-SiC substrates, a lapping-polishing plate combining magnetically controlled abrasive solidification orientation and a solid-phase Fenton reaction was prepared. Furthermore, the effects of the concentration ratio of abrasive to Fe3O4 and abrasive types on the physical properties of the lapping-polishing plate and the processing properties for single-crystal 4H-SiC substrates were studied to reveal the lapping-polishing mechanism of magnetically controlled abrasive solidification orientation—solid-phase Fenton reaction. The results show that the concentration ratio of abrasive to Fe3O4 and abrasive types affects the distribution of the magnetic chain string structure and the distribution of abrasive materials, affecting the plate's processing properties. The higher the abrasive concentration is, the higher the material removal rate (MRR), but it affects the abrasive orientation and the solid-phase Fenton reaction. In contrast, the high Fe3O4 concentration strengthens the solid-phase Fenton reaction and weakens the mechanical removal of the abrasive, resulting in low MRR and poor processing quality. When the abrasive and the concentration ratio of abrasive to Fe3O4 are diamond and 1:5, the MRR is the largest (46.5 nm/min), and a smooth surface with a surface roughness Ra of 0.89 nm can be obtained. The magnetically controlled abrasive solidification orientation—solid-phase Fenton reaction lapping-polishing process—is a chemical reaction and mechanical removal process. The chemical reaction can promote MRR and improve the lapping-polishing quality while affecting the lapping-polishing plate's surface microstructure and processing properties. The dynamic equilibrium between the material removal process of SiC substrates and the wear of lapping-polishing plates enable high-efficiency, high-quality and low-damage processing of SiC substrates. This method and plates can be potentially used to achieve the fine lapping and polishing of SiC substrates and other optoelectronic substrates.

Experimental investigation on abrasive flow Machining (AFM) of FDM printed hollow truncated cone parts

Abrasive flow machining (AFM) process is mostly used to finish the complex-shaped products that are difficult to finish by the traditional finishing processes like grinding, lapping honing, etc. AFM process employed a viscoelastic polymer-based finishing media, which is the suspension of viscoelastic polymer, abrasive particles, liquid synthesizer, and additives to finish the complex parts. It is used in various engineering applications such as trim die, automotive, aerospace, bio-medical implants. The Fused deposition modeling (FDM) process is one of the commercial 3D printing processes used for manufacturing prototypes for investment casting applications and end-use products. The stair-stepping effect is the most common surface defect that occurs during the FDM printing process. AFM process is an excellent solution to improve the surface quality of FDM printed parts. In this paper, AFM finishing media was developed using a natural waste polymer as base materials which carry SiC powder as abrasive particles, waste vegetable oil as the liquid synthesizer, and glycerine as additives. The viscosity of AFM media optimized using Taguchi's orthogonal array L9 based experimental design. In the current study, the hollow truncated cone shape of ABS (acrylonitrile–butadienestyrene) material was fabricated by the FDM process and then finished using a one-way AFM process. This paper examined the parametric dependencies of AFM process parameters on the internal finishing of FDM truncated cone parts. The improved surface roughness of the FDM printed hollow truncated cone has been investigated relating to the AFM process parameters. The maximum surface roughness has been achieved by 94.26%. The process parameters, i.e., the percentage of abrasive concentration, abrasive mesh size, layer thickness, and finishing time, were identified for the improved surface quality of FDM printed hollow truncated cone parts.

Role of Slurry Additives on Chemical Mechanical Planarization of Silicon Dioxide Film in Colloidal Silica Based Slurry

Chemical mechanical planarization (CMP) is a critical process for smoothing and polishing the surfaces of various material layers in semiconductor device fabrication. The applications of silicon dioxide films are shallow trench isolation, an inter-layer dielectric, and emerging technologies such as CMOS Image Sensor. In this study, the effect of various chemical additives on the removal rate of silicon dioxide film using colloidal silica abrasive during CMP was investigated. The polishing results show that the removal rate of silicon dioxide film first increased and then decreased with an increasing concentration of K+, pH, and abrasive size. The removal rate of silicon dioxide film increased linearly as the abrasive concentration increased. The influence mechanisms of various additives on the removal rate of silicon dioxide film were investigated by constructing simple models and scanning electron microscopy. Further, the stable performance of the slurry was achieved due to the COO- chains generated by poly(acrylamide) hydrolysis weaken the attraction between abrasives. High-quality wafer surfaces with low surface roughness were also thus achieved. The desirable and simple ingredient slurry investigated in this study can effectively enhance the planarization performance, for example, material removal rates and wafer surface roughness.

Quality prediction of polygonal helical curved tube by abrasive flow precision machining

The polygonal helical curved tube is the main form of rifling barrel, which surface quality determines the shooting accuracy of the gun. Abrasive flow machining (AFM) technology can significantly improve its inner surface quality. In order to study the influence of AFM technical parameters on the inner surface quality of polygonal helical curved tube, orthogonal experimental design (OED) was used as the research method in this paper. Through the analysis of variance (ANOVA) of experimental data, the degree of influence of inlet pressure, abrasive concentration, abrasive particle size, and machining time on the inner surface quality of polygonal helical curved tube was determined, and the optimal combination of process parameters was obtained. Under the optimal process parameters, the surface roughness Ra value in the inlet area of the polygonal helical curved tube was reduced to 0.080μm. The surface quality was significantly improved. Based on the regression analysis of experimental data, the quality prediction model of polygonal helical curved tube roughness by AFM was established to realize the effective prediction of surface quality after machining. The fitting value calculated by the model with optimal process parameters is close to the experimental value, which proves the accuracy and validity of the prediction model.

Modeling of forces and material removal rate in ultrasound assisted magnetorheological polishing (UAMP) of sapphire

In order to fully investigate the polishing performance of the Fe 3 O 4 /SiO 2 core-shell abrasive for sapphire material, it is necessary to conduct a comprehensive study into polishing forces and establish corresponding mathematical models. In this paper, based on the bonding strength of core-shell abrasive chains and the motion analysis of ultrasonic vibration in UAMP process, the mathematical models of shear force F τ and normal force F N generated on sapphire surface are established. Experiments were implemented to verify the reliability of the F τ and F N models under varying parameters, including the volume concentration of core-shell abrasives, excitation gap and working gap. The values and the variation trends of theoretical results are well in agreement with those of experimental results. Then, on the basis of the F τ and F N models and Preston equation, we proposed a modified material removal rate (MRR) model, in which the contributions of F N and F τ are all taken into consideration. Through the comparative analysis with the experimental results, the modified MRR model exhibits higher prediction accuracy than those models involving only F τ or F N . The high-precision MRR model will facilitate the deterministic removal of sapphire surface material in UAMP process. • Mathematical models of shear force and normal force in sapphire UAMP are established. • The reliability of the force models is verified by targeted experiments. • A modified MRR model based on the synergy of shear and normal force is developed. • The modified MRR model exhibits higher prediction accuracy than general MRR models.

Influence of process variables in the abrasive mixed electrical discharge machining of Ti–6Al–4V

In this present work, we investigate the Influence on process variables in abrasive mixed electrical discharge machining (AMEDM) of Ti–6Al–4V. Each processing variable has its own effect on the performance of AMEDM method. Polarity type, electrode type, current on time, duty cycle, gap voltage, flushing pressure and abrasive concentration are taken as input variables. Taguchi approach has been implemented to optimize the production of variables like Material removal rate (MRR), Tool wear rate (TWR), Wear ratio (WR) and Surface roughness (SR). It has been observed that the value of MRR is increased and the value of TWR decreases with the increase in the concentration of abrasive in kerosene oil. The mathematical outcome of ANOVA test, i.e., Polarity, current, duty cycle and flushing pressure has been presented in the manuscript. It has been observed that Current, flushing pressure and Polarity are the more influencing factors for TWR. Similarly, input variables like polarity, electrode type, on time and flushing pressure are, the more influencing factors for WR.