Free Abrasives Research Articles

Design Method for Finishing by Free Abrasive

Design Method for Finishing by Free Abrasive

Method for design of finishing processing with free abrasive

The dependences of changes in the Ra parameter of surface roughness during finishing processing with free abrasive when using different abrasive materials are analyzed. A method for designing such a technological operation as flow barrel polishing is proposed. An example of determining of the optimal sequence of using of abrasive materials during finishing is shown. Keywords:finishing, free abrasive, technological operation, surface roughness parameter, design, optimization aka111996@mail.ru, al.goncharow@yandex.ru, maxim.albom@yandex.ru, ilya32zog@gmail.com

Finishing Characteristics with Free Abrasive Grains and Cooling Performance of Internal Channels with Different Cross-Sectional Geometries

This study investigates the finishing characteristics of internal channels with different cross-sectional geometries using free abrasive grains and evaluates the cooling performance of these channels before and after finishing. Three types of channels with circular, triangular, and hexagram cross-sections were designed and fabricated using laser powder bed fusion (L-PBF). A fluid flow in the channel was evaluated using computational fluid dynamics simulations, and the finishing characteristics and cooling performances of the channels were experimentally investigated. The results indicated that the use of free abrasive grains enabled the improvement in the surface quality as well as the cooling performance of the channel. The cross-section of the channel affected the fluid flow in the channel and finishing progress. The initial surface roughness varied with the cross-section of the channel owing to the limitations of L-PBF, and the triangular section had a relatively uniform surface quality throughout the channel compared with the other cross-sections. The cooling time decreased with the surface area of the channel. To obtain the uniform surface quality, the application of a suitable cross-section is needed for the finishing process. The outcomes of this study demonstrate that a triangular-section channel is suitable for improving both surface quality and cooling performance.

АНАЛИЗ МЕТОДОВ ПРАВКИ КОЛЬЦЕВЫХ АЛМАЗНЫХ СВЕРЛ НА МЕТАЛЛИЧЕСКОЙ СВЯЗКЕ

The study objective is to analyze the existing methods to dress annular diamond drills of metal bonds and to develop new schemes of dressing used for diamond grinding tools.
 The paper is devoted to solving the problem, which consists in comparing different dressing methods, analyzing their disadvantages and advantages.
 Research methods are theoretical studies of various methods of annular diamond drill dressing.
 Novelty of the work: schemes for dressing annular diamond drills of metal bonds with free abrasive are developed.
 Research results: the existing methods and schemes for dressing annular diamond drills of metal bonds are analyzed, their main disadvantages and advantages are found. Dressing schemes for the free abrasive method are developed.
 Conclusions: when drilling hard non-metallic materials with annular diamond drills, the tool loses its functionality, glares and needs forced dressing. During the analysis, existing methods and possible dressing options are considered.

MODERN MATHEMATICAL MODELS OF PROCESSING WITH A FREE ABRASIVE

The paper presents the results of the analysis of modern mathematical models for processing with a free abrasive. The features of mathematical models for some methods of processing with a free abrasive are revealed. The requirements for a mathematical model for processing with a free abrasive by the stream finishing method are presented.

Effect of elastohydrodynamic characteristics on surface roughness in cylindrical shear thickening polishing process

The shear thickening fluid exhibits a non-Newtonian characteristic, i.e. the viscosity follows a power law with the increasing shear rate. The shear thickening polishing technology has been proposed and developed to realize the precision finishing, utilizing the slurry with free abrasives prepared by the shear thickening fluid. In this paper, the formation mechanism and evolution of surface roughness in the cylindrical shear thickening polishing process is investigated in the elastohydrodynamics theoretically and experimentally. The elastohydrodynamic properties and the surface roughness are modeled by a novel solution method, based on the integration of polishing pad’s elastic deformation and slurry’s hydrodynamics. The Taguchi orthogonal tests of polishing the cylindrical AISI 52100 steel with the foam polyurethane pad were conducted, and the experimental surface roughness Ra of 9.689 nm was achieved under conditions of loading force 10 N, α-Al2O3 powder with grain size 1 μm and concentration 20 wt%, starch powder with concentration 25 wt%. According to the comprehensive analysis of variance and level average response, it is revealed that the slurry’s viscosity has a great influence on the surface roughness. The effecting mechanisms of processing factors on the surface roughness are interpreted from the perspective of effects transition in aspects of viscosity, pressure distribution and single grain’s cutting depth, interestingly exhibiting significant differences from that of traditional polishing methods.

Surface Creation Using Free Abrasives Controlled by AC Electric Field

Surface Creation Using Free Abrasives Controlled by AC Electric Field

Study on the temperature field in the cutting zone for machining monocrystalline silicon wafer using free abrasive multi-wire saw

With increasing applications of integrated circuits, the requirements for the quality of the corresponding substrate silicon wafers have become more stringent. Slicing is a key step in the manufacturing of silicon wafers. At present, free-abrasive multi-wire saw (MWS) technology is commonly employed for substrate silicon wafer processing. However, the actual temperature field in the cutting zone is unclear because of the narrow cutting zone in multi-wire sawing. Although a simulation method was adopted in this study, the distribution of the slurry in the cutting zone remains ambiguous, causing a large difference between the simulation results. The temperature field is an important cause of warpage, which significantly affects wafer quality. In this study, an experiment and simulation of the temperature field in the cutting zone of a MWS of monocrystalline silicon with free abrasives were performed. First, an experiment was designed to measure the temperatures at different positions in the cutting zone. Then, based on the experimental data of the fluid pressure distribution and the temperature field in the cutting zone, after obtaining the heat source model, a simulation analysis was conducted, and the results are consistent with the experimental results. Finally, based on the heat flux model, the temperature field distribution in the cutting zone under different cutting conditions was simulated and analyzed. Temperatures of 36.7, 39.4, 40.7, and 42.8 °C were obtained at 22.5, 62.5, 137.5, and 177.5 mm, respectively, from the slurry entrance in the cutting zone. According to the heat source model based on the pressure distribution data of slurry in the cutting zone, the temperature values obtained via simulation at 22.5, 62.5, 137.5, and 177.5 mm from the slurry inlet were 35.4, 37.4, 41.5, and 43.1 °C, respectively. The maximum temperature difference is 1.8K°C, and the average temperature difference is 0.2K°C. Thus, the validity of the heat source model was verified. Further, based on the heat source model, the maximum temperature for cutting a 300-mm monocrystalline silicon wafer was predicted as 48.4 °C. Moreover, the wire speed was found to greatly influence the maximum temperature in the cutting zone. Tension also affects the temperature of the cutting zone, but to a lesser extent than the wire speed.

Theoretical model design for processing internal surfaces of machine parts with free abrasives that ensures the reliability of technological processes in digital manufacturing

The paper presents the research results of vibroabrasive processing of variously located part surfaces. An analysis of technological possibilities of processing with free abrasives in digital manufacturing was made. The dependability issue of technological processing is considered. Refined dependences were obtained to determine the mass of metal removed during processing and the steady-state roughness of the internal surface. The processing features of internal surfaces are revealed, taking into account the different ratio of length to the size of the cross section. In the course of experi-mental studies, the adequacy of the proposed dependencies was confirmed. A dependability as-sessment of the designed technological process at the stage of technological preparation was made, taking into account the possible spread of technological parameters. The results obtained make it possible to design highly efficient technological processes for processing parts with free abrasives and carry out technological preparation of digital production in an automated mode.

The Effect of Hydrogen Peroxide on Composite Lapping of Titanium Alloy (TC4) by Free Abrasive Assisted Fixed Abrasive

The Effect of Hydrogen Peroxide on Composite Lapping of Titanium Alloy (TC4) by Free Abrasive Assisted Fixed Abrasive

Modeling of material removal based on multi-scale contact in cylindrical polishing

In this paper, the material removal and the surface roughness in the cylindrical polishing with a soft pad and free abrasives are investigated theoretically and experimentally. Existing our studies have suggested that there is different contact deformation at dimension scales of millimeter, micrometer and nanometer. On that basis, the material removal model is proposed by integrating the contact at different scales in accordance with the Hertz contact, the Greenwood and Williamson's model (G-W model) of rough contact and the single grain's cutting depth. Furthermore, a model of surface roughness is built based on the idea that more materials are removed at the peak on the workpiece's surface, whereas few materials are removed at the valley. The polishing experiments and simulation of cylindrical AISI 52100 steel using the polyurethane polishing pad and the free abrasives of aluminum oxide powder were performed through the Taguchi orthogonal tests, which indicated that the simulation results were well consistent with the experimental results. Under the optimal conditions, the material removal rate (MRR) of 0.40 μm/min was achieved, and the surface roughness Ra was reduced from 104.90 to 20.22 nm after the polishing for 12 min. The contributions of the loading force, the abrasives concentration and the grain size on the MRR and the surface roughness are investigated in accordance with the variance and the level average response, and their reasons are discussed at different scales. It is revealed that the influences of loading force and grain size are significantly different at multi-scale. Furthermore, the parameters related to the contact (e.g., nominal contact area, average contact gap and single grain's cutting depth) under different conditions are studied.

MAIN TECHNOLOGICAL FACTORS DETERMINING THE EFFICIENCY AND QUALITY OF THE VIBRATION PROCESS

The factors that determine the efficiency and quality of vibration treatment are indicated. Characteristic cases of interaction of abrasive granules with the processed surface are noted. The influence of the hardness of the processed part material and the shape of its surface, as well as the influence of chemically active solutions on the efficiency and quality of vibration processing, is substantiated. The characteristics of abrasive granules and their volume ratio with the processed parts are given. It is indicated that the underestimation of the possibilities of vibration processing technologies is explained by their insufficient studies. It has been established that vibration processing, depending on the characteristics and composition of the processing medium, is a mechanical or mechanochemical removal of the smallest particles of metal or its oxides and plastic deformation of microroughness due to mutual collisions of the medium granules with the processed surface, caused by vibrations of the reservoir in which the processing medium and, the processed parts are placed. It is noted that, according to the classification, vibration treatment refers to mechanical processing methods and, in particular, to the group of mechanical-chemical processing methods or to combined methods when chemically active solutions are introduced into the working medium, It is also noted that vibration treatment refers to dynamic, and for technological purposes – to dimensionless processing methods, according to the type of tool used - to the group of processing methods with a free abrasive. It has been established that the efficiency of vibration processing depends on the oscillation modes of the vibrating machine, the mass of the processed parts and abrasive granules, the hardness of the parts material and the shape of their treated surfaces, the characteristics of the abrasive medium, the volume ratio of the parts and abrasive granules, as well as on the composition of the chemically active solution. The characteristic cases of interaction of abrasive granules with the processed surface are given. The situations of the highest processing productivity for performing the operations of vibration grinding, vibration polishing, washing and descaling have been established. It is noted how the hardness of the processed part and the shape of their surface affects the performance and quality of vibration processing operations. The characteristics of the working medium, which affects the efficiency and quality of vibration treatment, are given, including the influence of grain size and hardness of the material of abrasive granules. The volume ratios of abrasive and processed parts are considered. The types of actions on the vibration treatment processes are given.

Composition Optimization of Slurry for Polishing TA31 Titanium Alloy with Free Abrasive

Composition Optimization of Slurry for Polishing TA31 Titanium Alloy with Free Abrasive

Investigation of the effectiveness of the method of finishing the inner cylindrical surfaces of machine parts with a free abrasive using the effect of vibration cavitation

Finishing of high-precision machine parts is one of the most labor-intensive operations in the technological process. This process becomes especially difficult when it is necessary to ensure a high-quality surface in hard-to-reach places for parts made of materials with special physical and mechanical properties. In such cases, the solution to the problem may be the use of methods of processing with free abrasive particles. Based on the foregoing, it can be concluded that improving the efficiency of methods for processing parts with a free abrasive is the most important task for researchers in the field of mechanical engineering technology.The authors of the article carried out a series of experiments on finishing the inner cylindrical surfaces of machine parts of the “sleeve” type with a free abrasive using the effect of vibration cavitation. The study is of an applied nature - according to the design documentation for the product, it is necessary to achieve a roughness in the inner surface of Ra 0.80.

Modeling, simulation, and experimental verification on material removal and rounding process of centerless cylindrical finishing with free abrasives and soft pad

In this paper, the centerless finishing process using free abrasives and soft pad was developed and applied in fine machining the bearing cylindrical roller of AISI 52100 steel on self-made machine, improving roundness and its deviation on roller’s circular profile. A novel modeling and simulation method of material removal and rounding process for cylindrical workpiece was proposed in three-body abrasive wear pattern, combining geometry, kinematics, elastic contact, and single grain’s micro-cutting. The equivalent elastic modulus of roller and pad in contact is a key parameter for simulation, and its value was obtained through loading experiment and data processing. The finishing simulation and experiments were carried out under different loading forces. Their diameter’s results are in good agreement, and roundness’s results are in considerable agreement with error of less than 7%, demonstrating the validity of modeling and simulation method. Through data processing and analysis, it is indicated that the roundness is improved obviously; but with a slight material removal rate, the effect of loading force on roundness is greater than that of material removal. The reasons for above results are analyzed and discussed, taking into account three-body elastic contact, contact area and depth, and number of abrasive grains in finishing region.

Hydrodynamic action in slicing PV polysilicon with a novel fixed and free abrasive combined wire sawing

This paper presents a novel fixed and free abrasive combined wire sawing which uses the diamond wire with surface abrasive-groups interval distribution and combines with free SiC abrasives slurry to obtain sliced surface that can be textured by acid etching. During the sawing process, the ability that the free abrasives lapping the sawn surface has a positive correlation with the elasto-hydrodynamic (EHD) pressure, and the appropriate size of the free abrasives is related to the minimum film thickness of the cutting coolant. In this paper, the EHD action during the FFACWS is analyzed, and the film thickness equation and Reynolds equation of the sawing area are deduced. The influences of feed speed, wire speed, wire tensioning force, cutting coolant viscosity, core wire diameter, and surface structure parameters on EHD pressure and film thickness are analyzed, which provides theoretical reference for selection of the free abrasives diameter and analysis of their lapping effect on the slice surface. The research results show that the EHD pressure changes periodically in the direction of the wire axis in the entire sawing area. The change period is the same as a structural change period of the abrasive area (AA) and the bare wire area (BWA) on the wire surface. In one period, there are two EHD pressure peaks. The size range of free abrasives should be greater than the protruding height of the fixed abrasives on the diamond wire and less than the minimum film thickness in BWA, so that the free abrasives can be constrained in BWA to lap the slice surface.

Experimental Study of the Impact of a Vibrating Wire on Free Abrasive Machining as Correlated to the Modeling of Vibration Subject to an Oscillating Boundary Condition

Abstract In this paper, we study experimentally the impact of a vibrating wire on the free abrasive machining (FAM) process in removing material from the surface of brittle materials, such as silicon. An experimental setup was designed to study the FAM process on silicon substrate surface by using a slurry-fed wire with a periodic excitation. An analytical solution of a wire moving axially, subject to an oscillating boundary condition with damping from abrasive slurry, was derived based on the partial differential equation of motion. Experiments were conducted on the apparatus using a wire with an oscillating boundary. It was found that the amplitudes of vibration were larger at the side of the oscillatory boundary, which caused more FAM interaction near the edge of the oscillatory boundary with larger material removal that was measured and validated. Furthermore, experiments were conducted to elucidate the effectiveness of brittle material removal using FAM with abrasive grits: (i) under dry condition, (ii) with water, and (iii) with abrasive slurry. Experimental results showed that the vibration of wire resulted in plastic deformation on the surface of silicon wafer. The abrasive grits in slurry driven by a vibrating wire generated material removal through observable grooves and fractures on the surface of silicon due to FAM in just a few minutes. The grooves from FAM process is an outcome of brittle machining through fracture formation and concatenation, generated by the indentation of abrasive grits on the silicon surface.

Slicing Ceramics on Material Removed by a Single Abrasive Particle.

Multi-wire saw machining (MWSM) used for slicing hard-brittle materials in the semiconductor and photovoltaic industries is an important and efficient material removal process that uses free abrasives. The cutting model of single-wire saw machining (SWSM) is the basis of MWSM. The material removal mechanism of SWSM is more easily understood than MWSM. A mathematical model (includes brittle fracture and plastic deformation) is presented in this paper for SWSM ceramic with abrasives. This paper determines the effect of various machining parameters on the removal of hard-brittle materials. For brittle fracture of SWSM ceramics, the minimum strain energy density is used as a fracture criterion. For plastic deformation of SWSM ceramics, the material removal is calculated using equations of motion. Actual wire-sawing experiments are conducted to verify the results of the developed mathematical model. The theoretical results agree with experimental data and practical experience. From the developed mathematical model, brittle fracture plays a major role in material removal of SWSM ceramics. Wire speed (S) and working load (P) are positively correlated with material removal of SWSM ceramics. The coefficient of friction is low, a lateral crack, which propagates almost parallel to the working surface, leads to more brittle fracture and material removal is increased.

Surface Machining of Corundum-Ceramic Components by Free Abrasive

The surface machining of corundum-ceramic components by free abrasive is discussed. The influence of the following factors on the final surface roughness is determined: the type of machining (tumbling or vibrational tumbling), the shape of the abrasive bodies, the presence or absence of machining fluid, the machining time, and the drum speed in tumbling. On that basis, recommendations are presented.

Advances in fabrication of ceramic corundum abrasives based on sol–gel process

Corundum abrasives with good chemical stability can be fabricated into various free abrasives and bonded abrasive tools that are widely used in the precision machining of various parts. However, these abrasives cannot satisfy the machining requirements of difficult-to-machine materials with high hardness, high strength, and strong wearing resistance. Although superhard abrasives can machine the above-mentioned materials, their dressing and manufacturing costs are high. By contrast, ceramic corundum abrasives fabricated by sol–gel method is a cost-effective product between conventional and superhard abrasives. Ceramic corundum abrasives exhibit self-sharpening and high toughness. In this review, the optimization methods of ceramic corundum abrasive properties are introduced from three aspects: precursor synthesis, particle shaping, and sintering. Firstly, the functional mechanism of seeds and additives on the microstructural and mechanical properties of abrasives is analyzed. Specifically, seeds can reduce the phase transition temperature and improve fracture toughness. The grain size and uniformly dense structure can be controlled by applying an appropriate amount of multicomponent additives. Then, the urgent need of engineering application and machinability of special shape ceramic corundum abrasives is reviewed, and three methods of abrasive shaping are summarized. The micromold replication technique is highly advanced and can be used to prepare functional abrasives. Additionally, the influence of a new sintering method, namely, two-step sintering technique, on the microstructural and mechanical performance of ceramic corundum abrasives is summarized. Finally, the challenge and developmental trend of the optimization of ceramic corundum abrasives are prospected.