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In order to enhance the efficiency of stone sculpture machining while reducing natural stone waste and environmental pollution, a method for the efficient and green sawing of natural stone sculptures using industrial robots is proposed. The model contour is used as the directrix of the ruled surface to construct a ruled surface model that minimizes volume. The contour curve corresponding to this minimized-volume ruled surface model serves as the machining path for an integrated robotic diamond wire cutting system. A ruled surface model of Stanford Bunny was obtained by sawing a marble block using the robotic diamond wire cutting system. The experimental results show that the material removal rate of the robotic diamond wire cutting is 1.37 times that of saw blade cutting and 2.30 times that of grinding. The volume of stone powder generated during the processing was 0.16×10⁷mm³, accounting for only 1.47% of the total stone powder produced during the grinding process. In summary, the proposed method not only enhances processing efficiency but also reduces natural stone waste and mitigates environmental pollution. [ABSTRACT FROM AUTHOR]

Sapphire crystal with excellent properties is widely used as substrate materials for optoelectronics and microelectronics industries. Subsurface crack damage (SSD) will occur in the diamond wire saw slicing process of the sapphire wafer, which is related to the quality of the as-sawn wafer and the cost of subsequent processing. Therefore, rapid and effective detection of SSD is required in production. However, current detection methods are time-consuming and labor-intensive, thus requiring a fast, effective, and low-carbon evaluation method. In this paper, based on the current diamond wire saw slicing process parameters range of sapphire crystal in actual production, sawing experiments were carried out to study the surface and subsurface crack damage morphology characteristics, evolution law of surface roughness (Rz), and SSD. Furthermore, the mapping relationship between Rz and SSD was established by the numerical fitting method. The results show that, in the range of processing parameters for practical industrial applications, the surface of the as-sawn wafer was mainly formed by material brittleness removal, the subsurface presented a small number of micro-cracks and brittle fracture damage, and the median crack propagation direction was shifted. Within the range of process parameters used in this study, the maximum SSD value of the sapphire wafer is 20.07 µm, the minimum value is 11.67 µm, and the corresponding Rz values are 11.13 µm and 8.12 µm, respectively. Both SSD and Rz decreased with the increase in saw wire speed and the decrease in specimen feed speed. There is a nonlinear relationship of monotone increase between the two, which is SSD = 0.15Rz3 − 4.87Rz2 + 55.49Rz − 195.23. The research results can be used to evaluate SSD quickly and effectively by measuring as-sawn sapphire wafer Rz that can provide an experimental reference for wire-sliced SSD evaluation, wafer quality improvement, and processing parameter optimization. [ABSTRACT FROM AUTHOR]

In this paper, based on the principle of wire saw cutting, the simulation model of scribing of monocrystalline silicon (100) planes has been established. The stress field distribution is obtained by applying loads, and the depth of crack damage is calculated. This enables the influence of different process parameters on the crack damage of silicon wafers to be analyzed. Furthermore, the effect of process parameters on crack damage is verified by observing the surface morphology of silicon wafers through cutting experiments.​The results indicate that as the particle half angle increases, the stress region under single-crystal silicon decreases and the stress value increases. The material crack length decreases with increasing wire speed and particle density and increases with increasing feed speed. The trend is approximately linear. The findings of this study are of value in optimizing the cutting process of brittle materials, such as monocrystalline silicon, and in reducing material damage. [ABSTRACT FROM AUTHOR]

NdFeB is the highest output value permanent magnet material at present, which has extremely high magnetic properties and is widely used. In the production process of NdFeB, cutting is an indispensable process, and high precision as-cut surface characteristics can reduce the cost of subsequent processes. In this paper, the single factor sawing experiment of NdFeB was carried out by using the range of processing parameters in industrial production. The effects of workpiece feed speed, saw wire speed, workpiece processing size and diamond saw wire wear on sawing surface morphology, surface material brittleness removal ratio, roughness and waviness were studied. The research shows that the surface characteristics of the workpiece sawed in the stable wear stage of the diamond saw wire are the best. In all service stages of the saw wire, reducing the feed speed and workpiece processing size, and increasing the wire speed will reduce the surface roughness and waviness, reduce the number and size of pits, and reduce the proportion of brittle removal areas. The research results provide an experimental reference for the optimization of diamond wire saw cutting parameters of NdFeB. • Influence of wire wear on surface characteristics in NdFeB sawing is analyzed. • Cut surface characteristics in early service stage of saw wire are relatively poor. • Better surface characteristics are achieved in stable service stage of the saw wire. • Abrasives on saw wire surface are worn flat and fall off in its later service stage. • Increasing wire speed, decreasing ingot feed speed and size can improve the surface characteristics. [ABSTRACT FROM AUTHOR]

Ceramic materials are widely used in national defense, military industry, information technology and other fields, are a typical hard and brittle material. Microstructure and mechanical properties not only affect the overall performance of ceramic parts, but also affect their machining performance. The diamond wire sawing technology has the characteristics of high machining efficiency, small crack damage, low cutting loss, and green environmental protection, and is widely used in the cutting of hard and brittle materials. Therefore, exploring the influence of ceramic microstructure on diamond wire sawing has theoretical significance and practical value. This article first prepares high-performance alumina ceramics with different grain sizes to provide preliminary material preparation for diamond wire sawing; Then, characterization experiments such as microstructure, mechanical properties, fracture and indentation morphology, and indentation depth were conducted to provide technical methods for in-depth research on material removal in diamond wire sawing; Finally, the removal form, chips, roughness, and removal rate of diamond wire sawing were studied to obtain the influence of different microstructures of alumina ceramics on diamond wire sawing, providing a certain theoretical and technical basis for efficient machining of high-performance ceramics by diamond wire saw. [ABSTRACT FROM AUTHOR]

Electroplated diamond wire sawing is widely used as a processing method to cut hard and brittle difficult-to-machine materials. Currently, obtaining the sawing capability of diamond wire saw through the wire bow is still difficult. In this paper, a method for calculating the sawing capability of diamond wire saw in real-time based on the wire bow is proposed. The influence of the renewed length per round trip, crystal orientation of sapphire, wire speed, and feed rate on the wire sawing capability has been revealed via slicing experiments. The results indicate that renewing the diamond wire saw, and reducing the wire speed and feed rate can delay the reduction in sawing capability. Furthermore, controlling the value of renewed length per round trip can make the diamond wire saw enter a stable cutting state, in which the capability of the wire saw no longer decreases. The sawing capability of diamond wire saw cutting in the A-plane of the sapphire is smaller than that of the C-plane, and a suitable feed rate or wire speed within the range of sawing parameters studied in this study can avoid a rapid decrease in the sawing capability of the wire saw during the cutting process. The knowledge obtained in this study provides a theoretical basis for monitoring the performance of the wire saw, and guidance for the wire cutting process in semiconductor manufacturing. In the future, it may even be possible to provide real-time performance parameters of diamond wire saw for the digital twin model of wire sawing. [ABSTRACT FROM AUTHOR]

In diamond wire saw cutting monocrystalline silicon (mono-Si), the material brittleness removal can cause microcrack damage in the subsurface of the as-sawn silicon wafer, which has a significant impact on the mechanical properties and subsequent processing steps of the wafers. In order to quickly and non-destructively obtain the subsurface microcrack damage depth (SSD) of as-sawn silicon wafers, this paper conducted research on the SSD prediction model for diamond wire saw cutting of mono-Si, and established the relationship between the SSD and the as-sawn surface roughness value (SR) by comprehensively considering the effect of tangential force and the influence of the elastic stress field and residual stress field below the abrasive on the propagation of median cracks. Furthermore, the theoretical relationship model between SR and SSD has been improved by adding a coefficient considering the influence of material ductile regime removal on SR values based on experiments sawing mono-Si along the (111) crystal plane, making the theoretical prediction value of SSD more accurate. The research results indicate that a decrease in wire speed and an increase in feed speed result in an increase in SR and SSD in silicon wafers. There is a non-linear increasing relationship between silicon wafer SSD and SR, with SSD = 21.179 Ra4/3. The larger the SR, the deeper the SSD, and the smaller the relative error of SSD between the theoretical predicted and experimental measurements. The research results provide a theoretical and experimental basis for predicting silicon wafer SSD in diamond wire sawing and optimizing the process. [ABSTRACT FROM AUTHOR]

Diamond wire saws are indispensable machines for the extraction and processing of dimension stones. The cutting speed, energy consumption and wear rate of the diamond beads are the most important factors in assessing the efficiency of a diamond wire saw. The parameters that influence the efficiency of the diamond wire saw can be divided into controlled and uncontrolled parameters. Uncontrolled parameters cannot be influenced directly and are related to the rock types and their properties such as strength, hardness and abrasiveness. Controlled parameters are related to the operating parameters and technical characteristics of the machine. The energy consumption and the service life of the diamond wire are directly related to the characteristics of the machine and the design of the diamond wire, such as the power of the drive motor, the diameter of the drive wheel, diamond grit size and the diameter of the wire. The operating parameters of the diamond wire saw, such as cutting speed, cutting surface, cutting angle, wire tension and cooling water flow, also have a significant influence. Based on previous studies, the influence of the above parameters on the consumption of energy and wear rate of diamond beads in the operation of a diamond wire saw was analyzed.

Cutting rate in diamond wire method is one of the most important criteria in evaluation process of this method. In this research, using numerical modeling and PFC3D software, the effect of controllable parameters on the cutting rate have been investigated, the optimal values of these parameters have been determined, and finally an empirical relationship between these parameters and the cutting rate of diamond wire has been developed. These parameters include the diamond wire peripheral speed, number of beads per unit length of the wire, cutting machine pullback amperage and beads diameter. Numerical simulation and its validation are based on experiments performed on a granite stone sample. Numerical modeling results show that the wire peripheral speed and pullback amperage are directly related to the cutting rate. Optimal values for these parameters are the highest possible value. In other words, by technology advancement and ability to increase values of these parameters in wire cutting machines, higher cutting rates can be achieved. Evaluation of the number of beads per unit length of wire shows that by increasing it to 36 beads, the cutting rate increases, but with further increasing, cutting rate remains almost constant. Therefore, 36 beads per length unit of wire is the optimal value. Evaluation of the effect of the bead diameter on the cutting rate shows that the maximum cutting rate occurs when the bead diameter is equal to 1 cm. By further increasing of this parameter, cutting rate decreases. Therefore, optimal value of bead diameter is 1 cm. By comparing the effects of the mentioned parameters on the cutting rate, machine pullback amperage can be expressed as the most effective parameter. Finally, using multivariate regression, an experimental relation between the cutting rate and the mentioned parameters with a correlation coefficient of 0.98 has been achieved. This relation can be used to predict and improve the performance of diamond wire saw in granite stones' cutting. Highlights: The diamond wire cutting process is modeled with the aim of investigating and improving of its performance using PFC3D software. TBy adjusting and properly selecting each of controllable parameters, an appropriate economic diamond wire saw machine with low energy consumption and high production rate can be achieved. For granitic rock, the optimal values for the wire peripheral speed and pullback amperage are the highest possible value, the optimal number of beads per length unit of wire is 36 and the optimal bead diameter is one centimeter. The machine pullback amperage can be expressed as the most effective parameter on the cutting rate. The empirical equation between the cutting rate and four controllable parameters is presented that it is significant in terms of the multiplicity of parameters involved in optimization. [ABSTRACT FROM AUTHOR]

The structured groove surface is one of the important surfaces in the field of reducing fluid drag or contact friction. The research on the manufacturing technology of the structured groove drag or friction reduction surface has important theoretical significance and practical value for the engineering application of the theoretical research results of the drag or friction reduction of the surface. In order to grind structured groove surface, a new topological mapping grinding strategy for structured groove surfaces is innovated based on topology. In order to verify the feasibility of this strategy, the topological features of the structured groove surface were firstly analyzed and modeled, and the topological feature parameters were extracted. Based on the feature parameters, the homeomorphic mapping equation of the grinding process is established, and according to the established equation, a circular arc-shaped helical structure grinding wheel with convex properties is designed, and the effect of grinding parameters on the structured groove surface is simulated and analyzed. Finally, a wire-wound structured grinding wheel with a diamond wire saw as the abrasive carrier was manufactured, and the experimental investigation of grinding structured groove surface was carried out. The results show that the innovative topology grinding strategy is feasible; the grinding wheel designed based on the topological features of the structured groove surface can realize the topological mapping grinding of the structured groove surface; the change of grinding parameters can lead to the change of the geometric size of the groove, but the topological properties remain unchanged. [ABSTRACT FROM AUTHOR]

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The diamond wire sawing technology has been widely used in cutting sapphire crystal, and the surface roughness and morphology of as-sawn sapphire wafers are important indexes of the cutting quality. With the development of diamond wire saw cutting technology to high wire speed, this paper conducted diamond wire sawing sapphire crystal experiments within the industrial high saw wire speed of 1000–1600 m/min, and the effect of cutting parameters on the as-sawn wafers surface roughness and morphology was analyzed. Furthermore, a diamond wire saw cutting numerical calculation model was established based on the wire sawing mechanism and sapphire crystal material removal mechanism, and the model was verified by sawing experiments. The influences of abrasive density and size on the surface roughness of the as-sawn wafers were predicted using the sawing model which provides a theoretical reference for the rationally adopting saw wire parameters to improve the cutting quality of sapphire crystal under industrial cutting parameters. The results show that within the range of parameters studied in this paper, the sapphire crystal material is mainly removed in brittle mode. Increasing saw wire speed from 1000 to 1400 m/min and decreasing specimen feed speed from 0.5 to 0.05 mm/min, increasing the abrasive density, and decreasing the abrasive size are all beneficial to decrease the as-sawn wafers surface roughness. Increasing the saw wire speed and decreasing the feed speed are beneficial to reduce the number of brittle pits and saw marks, the period of waviness on the as-sawn wafer surface, and improve the as-sawn wafer surface morphology. [ABSTRACT FROM AUTHOR]

Diamond multi-wire slicing technology is the main method for producing the solar cell substrate based on monocrystalline silicon. To reduce the production cost and increase the production efficiency during the sawing process, the diameter of the diamond saw wire is becoming thinner, and the sawing speed is getting faster, which leads to an increasingly prominent problem of saw wire breakage during the slicing process. To understand the breaking characteristics of diamond saw wire and evaluate the reliability of the saw wire during the sawing process, the tensile testing of saw wires was carried out in this paper. And based on the Weibull function, the breaking force was analyzed statistically. A maximum tension force model for the saw wire during the sawing process was established. And based on the maximum tension force model and Weibull reliability function, the influence of various process parameters on the reliability of the wire web was analyzed. The results indicated that as the usage time of the saw wire increases, the breaking force gradually decreases and stabilizes. Compared to the fresh saw wire, the reliability of the used saw wires is significantly reduced. As the abrasive distribution density and the wire speed increases, the reliability of the wire web gradually increases. Conversely, as the feed speed and the pretension of the saw wire increase, the reliability of the wire web gradually decrease. The results of this paper provide a theoretical approach for assessing the reliability of diamond saw wire web during the sawing process. It also provides guidance for optimizing process parameters to enhance the reliability of the wire web. • Tensile test of diamond saw wires with different wear level was conducted. • Reliability of different worn saw wires is analyzed based on Weibull function. • Maximum tension model of the saw wire is established during the processing. • Influence of various parameters on the wire web reliability is studied. [ABSTRACT FROM AUTHOR]

• Obtained the fracture strength of mono-Si wafers by bending tests and simulation. • The fracture strength of mono-Si wafers exhibits strong anisotropy. • The anisotropy of fracture strength is due to different load-bearing cracks. • Relationship between roughness, saw marks with the fracture strength is revealed. Diamond wire slicing technology is the main method to manufacture the substrate of the monocrystalline silicon-based solar cells. With the development of technology, the size and thickness of monocrystalline silicon wafer are respectively getting larger and thinner, which cause an increase in silicon wafer fracture probability during wafer processing and post-processing. And the change of the sawing speed, saw wire diameter and abrasive size also affect the wafer's surface characteristics, thereby affect its fracture strength. In this paper, monocrystalline silicon wafer with large size of 210 mm × 210 mm was taken as the research object, 4-point bending test was carried out on each series of silicon wafers. The load–displacement curves during bending test were collected, and the fracture stress values were calculated by finite element method. The characteristic fracture strength and Weibull modulus of each series of silicon wafers were obtained through the statistical analysis of the data using Weibull distribution function. The effect of the silicon wafer thickness, the position of the silicon wafer in the silicon brick (usage time of the saw wire varies), and the bending test direction on the fracture characteristics was analyzed. The results showed that the increase of thickness increase the characteristic fracture strength of silicon wafer. The characteristic fracture strength of the front wafers (sawn by the fresh wire) is the smallest, while the characteristic fracture strength of the middle wafers and the rear wafers (sawn by the worn wire) are similar. The characteristic fracture strength of bending in the direction of perpendicular to the saw marks is 2–3 times that of bending in the direction of parallel to the saw marks. The reason of the difference of characteristic fracture strength was analyzed based on the surface morphology, roughness, and the saw marks of silicon wafer. In this paper, the fracture characteristics of large size monocrystalline silicon wafer are studied to provide fracture data support for industry production. The mechanism and main effect factors of silicon wafer fracture are revealed, which provides directions for improving the sawing quality and reducing the fracture probability during wafer production process and post-processing. [ABSTRACT FROM AUTHOR]

[Display omitted] • An analytical model for the initiation and deflection of the surface radial crack is proposed. • Driving forces for the initiation and deflection of radial cracks are analyzed. • Effects of 4H-SiC anisotropy on cracking behavior and mechanical properties are investigated. Cracking behavior caused by the anisotropy of single-crystal silicon carbide (SiC) brings challenges to the quality of the diamond wire sawing and grinding process. In this study, the effects of SiC anisotropy on machanical properties is analyzed based on Griffith's theory. The results indicate that the fracture toughness and the fracture strength exhibit anisotropy. At the same time, an analytical model for the initiation and deflection of the surface radial crack is proposed based on the scratching stress field. On the basis of these results, the anisotropic machanism of the surface radial crack initiation, deflection, the surface radial crack initiation (SRCI) depth, and the residual scratching depth are investigated in combination with the single abrasive scratching experiment. The shear stress and the maximum principal stress are the primary driving forces for the initiation and deflection of surface radial crack, respectively. The direction of the minimum shear strength and the fracture strength determines the anisotropy of cracking behavior. Meanwhile, the anisotropy of the SRCI depth and the residual scratching depth is caused by the fracture strength anisotropy. This research offers fundamental insights into the anisotropic cracking behavior of SiC, thereby contributing to the precise control of crack damage and improve the quality of the SiC diamond wire sawing and the as-cut wafers grinding process. [ABSTRACT FROM AUTHOR]

Silicon-based solar photovoltaics cells are an important way to utilize solar energy. Diamond wire slicing technology is the main method for producing solar photovoltaics cell substrates. In order to reduce production costs and improve the production efficiency, the solar photovoltaics cell substrates silicon wafers are developing in the direction of large size and ultra-thin, and the diamond wire slicing technology is developing in the direction of high wire speed and fine wire diameter. These aspects cause an increase in the fracture probability of silicon wafer during the processing and increase costs. In this paper, a comprehensive review has been conducted on silicon wafer fracture with the latest research. Firstly, the strength characteristics of ideal crystalline silicon are summarized and discussed. The ideal crystalline silicon has a large mechanical strength, and the tensile strength in the non-dissociation direction is more than 10 GPa, while the fracture strength of silicon wafers is only 100 MPa–500 MPa. This is because there is subsurface damage on the wafers during slicing processing. Then the testing methods and statistical methods of silicon wafer fracture strength are introduced. The testing methods mainly include 3-point bending test, 4-point bending test, and biaxial bending test. Collecting load-displacement data during bending test can further calculate the fracture stress of silicon wafers through linear stress analytical formulas and finite element methods. Then, the Weibull function is used for statistical analysis to obtain the fracture strength of the silicon wafer. Finally, the research literatures on the theoretical modeling of silicon wafer fracture strength and the calculation model of silicon wafer fracture probability under different load conditions are introduced. This review contributes to a comprehensive understanding of the mechanical strength degradation and fracture mechanism of silicon wafers, and provides critical insights for future research interests. [ABSTRACT FROM AUTHOR]

The slicing of silicon ingots using electroplated diamond wires is a fundamental process in the creation of semiconductor devices such as chips and photovoltaic cells. Composite electroplating, a process that uses nickel (Ni) plating to fix diamond particles onto a steel wire, is a critical step in the manufacturing of these diamond wires. In this work, chromium (Cr)-coated diamond was used to achieve rapid and high-quality composite electroplating, thereby aiding the production of high-performance diamond wire saws. The Cr-coated diamond micro-powder was prepared utilizing vacuum slow evaporation technology at a temperature of 850 °C. This resulted in a uniform and firm Cr coating that was firmly bonded to the diamond surface via Cr 3 C 2. Subsequent electrochemical tests were conducted in the composite electroplating bath. Linear scanning voltammetric curves revealed that the Cr-coated diamond was capable of inducing a more positive shift in the overpotential of Ni deposition, thus enhancing the reaction beyond that of uncoated diamond micro-powder. Additionally, the electrochemical impedance spectra indicated a decrease in charge transfer resistance during composite electroplating, attributable to the conductivity of the Cr-coated diamond. Electroplated diamond wires incorporating Cr-coated diamond demonstrated a greater abrasive density per unit length. SEM results showed that Ni was able to deposit on the Cr-coated diamond surface, resulting in the abrasives being completely covered by the Ni plating. The Cr-coated diamond wire exhibits a stronger resistance to abrasive detachment after cutting, which could increase the diamond-protrusion of the wire. The utilization of Cr-coated diamond micro-powder as an abrasive is anticipated to enhance the manufacturing efficiency of diamond wires and improve product quality, thereby promoting advancements in hard and brittle material processing technology. [ABSTRACT FROM AUTHOR]

The electroplated diamond wire saw has been widely used in the production of semiconductors, photovoltaic devices, etc. Composite electroplating is an important process in the production of electroplated diamond wire saws. The utilization of nickel (Ni)-coated diamonds is a widely adopted approach to enhance the efficiency of the composite electroplating process employed in the manufacturing of wire saws. However, the pristine diamond does not chemically react with Ni, and the interfacial bonding strength between the Ni coating and the diamond is relatively weak. This frequently results in the detachment of diamonds from the Ni coating during the cutting process. To solve this problem, titanium (Ti)-coated diamonds were used in the preparation of wire saws. We had specially developed a vacuum slow evaporation technology to produce diamond micro-powder (8 μm) with uniform conductive Ti coatings that were firmly bonded with diamond through the interfacial product TiC. A series of electrochemical test results were used to demonstrate the effect of Ti coating on the composite electroplating process. The linear scanning voltammetry curves showed that the addition of Ti-coated diamond shifted the overpotential of composite electroplating in a positive direction, so it promoted the electrodeposition reaction more than diamond powder. The electrochemical impedance spectroscopy revealed that the conductive Ti-coated diamond reduced the charge transfer resistance during composite electroplating. The Ti-coated diamond micro-powder was completely enveloped by an electroplated Ni layer, and TiC formed between the Ti coating and the diamond provided a stronger interfacial bonding force compared to that of the Ni-coated diamond micro-powder. After cutting, the Ti-coated diamond was found not to fall off the wire saw. The use of Ti-coated diamond micro-powder as an abrasive will significantly improve the product quality of mass-produced electroplating diamond wire saws. [Display omitted] • Ti-coated diamond was prepared by vacuum slow evaporation technology. • Uniform Ti coating was chemically bonded to diamond by interfacial product TiC. • Ti-coated diamond wires exhibited superior resistance to abrasives fall off. [ABSTRACT FROM AUTHOR]

When diamond wire saw is used in machining silicon nitride ceramics (Si 3 N 4 ceramics), the ultra-hardness of Si 3 N 4 causes the saw wire to wear out, which leads to the saw wire cutting performance constantly changing during its life cycle, and thus the machined quality of Si 3 N 4 ceramics is affected. Surface roughness and topography are important indicators of the quality of the machined surface. In this paper, the diamond wire saw cutting experiment of Si 3 N 4 ceramics was carried out, the effect of the evolution of saw wire cutting performance on the surface roughness and topography of Si 3 N 4 ceramics as-sawn slices was investigated based on the analysis of the changes of saw wire wear topography, breaking force, bow angle and kerf loss during the sawing process. The results show that the surface roughness along the saw wire motion direction and the workpiece feed direction tends to decrease and then increase with the evolution of the cutting performance of the saw wire, which accords well with the trend of the as-sawn slices surface morphology. The results of the study can provide experimental reference for the development of high precision diamond wire saw cutting technology for Si 3 N 4 ceramics. [ABSTRACT FROM AUTHOR]

Hard and brittle materials have the characteristics of high hardness and brittleness, wear resistance and good chemical stability. They are widely used in aerospace, mining, metallurgy, information, military and other fields. However, its cutting performance is very poor, which is known as a typical difficult to machine material. In particular, semiconductor materials such as ceramics put forward higher requirements for processing efficiency, processing quality and sawing loss. Diamond wire saw machining technology has the characteristics of high processing efficiency, small crack damage, low sawing loss and green environmental protection. It is widely used in the machining of hard and brittle materials. This paper summarizes the history and current situation, cutting mechanism and cutting technology of diamond wire saw machining hard and brittle materials, and puts forward relevant solutions for the problems existing in diamond wire saw machining hard and brittle materials, which has theoretical reference value and practical significance for the further research of diamond wire saw machining hard and brittle materials. [ABSTRACT FROM AUTHOR]

In this study, the magnetic field-based abrasive grain patterning for the production of electroplating diamond wire saws was studied. During the manufacturing process of the electroplating diamond wire saw, a permanent magnet was used to perform magnetization of the carbon steel wire. In addition, the following two methods were further used to perform partial degaussing on the carbon steel wire. The first method refers to the laser degaussing method, and the second method refers to the electromagnetic degaussing method, followed by performing electroplating on the carbon steel wire that has undergone the degaussing process. The impacts of these two methods on the magnetization characteristics of the carbon steel wire were studied, the magnetic induction strength of the zone of degaussing, range of the zone of degaussing, production speed, etc., in order to reach a conclusion on the methods for degaussing of a carbon steel wire. In this study, a nanosecond laser with a wavelength of 355 nm was used to perform a partial degaussing treatment on the surface of a magnetized carbon steel wire. When the laser fluence is 11.56 J/cm2, the controlled degaussing region of the abrasive grains could be minimized to 83.8 μm. [ABSTRACT FROM AUTHOR]

Using ultra-fine wire saw to cut solar grade silicon wafer is a very precise technology. In the past 20 years, researchers have done a lot of research and made great progress. The cutting method of silicon rod has developed from single line cutting to multi line simultaneous cutting, which greatly improves the production efficiency and the yield of silicon rod. However, the problems of high cutting loss, low cutting efficiency, and large surface damage of silicon wafer need to be solved; The surface of wire saw line has developed from smooth surface to coated diamond abrasive, which greatly improves the service life of wire saw line; The method of coated diamond abrasive on the surface of wire saw line has developed from resin consolidation to electroplating consolidation, which greatly improves the service life of wire saw line it improves the firmness of the coating; The arrangement of wire saw wire has developed from single wire to multi wire stranding, which makes the wire saw wire can cut large-size silicon rod; The minimum thickness of silicon wafer that can be cut is about 100–140 µm according to the perspective of stress analysis, while the excetive value should be located by more research. [ABSTRACT FROM AUTHOR]

Diamond wire saw cutting technology has been widely used in the slicing of sapphire crystal. The ultra-high hardness of sapphire makes the sawing characteristics of diamond saw wire constantly change. At present, there is a lack of in-depth understanding about the influence of sawing characteristics on the quality of sapphire as-sawn wafer, which leads to the unreasonable matching between the process parameters and the sawing characteristics of the saw wire, and reduces the as-sawn wafer quality and the saw wire life. In this paper, the slicing sapphire crystal experiment was carried out with constant process parameters and the variation of saw wire bow angle, nominal diameter and saw kerf loss, surface morphology and surface roughness of the as-sawn wafer during the whole life cycle of the saw wire from initial cutting to breakage was studied. The evolution mechanism of wear and sawing characteristics in the whole life cycle of saw wire was explored, and a reasonable processing scheme which can match the sawing characteristics was put forward. The research results show that in the whole life cycle of the saw wire, the abrasives emerge from the plating layer in turn, then the cutting edge are blunted, and finally the abrasives are greatly flattened and a small amount of falling off. Saw wire has experienced initial wear, stable wear and sever wear, and the proportion of three stages in the whole life cycle is about 0.3: 0.6: 0.1. Compared with the initial stage of wear and the late stage of rapid wear, the saw wire has higher sawing characteristics and better as-sawn wafer quality in the middle stable wear period. The sawing characteristics of new saw wire is relatively weak at the beginning of cutting, so the feed speed of workpiece should be increased gradually from low to high; When most of the abrasives finish sharpening edge, a relatively stable and high feed speed can be adopted; When the abrasives are obviously flattened or fall off, the feed speed should be decreased to accommodate the significantly reduced. cutting performance of diamond saw wire. [ABSTRACT FROM AUTHOR]

Diamond wire sawing has been developed to reduce the cutting loss when cutting silicon wafers from ingots. The surface of silicon solar cells must be flawless in order to achieve the highest possible efficiency. However, the surface is damaged during sawing. The extent of the damage depends primarily on the material removal mode. Under certain conditions, the generally brittle material can be machined in ductile mode, whereby considerably fewer cracks occur in the surface than with brittle material removal. In the presented paper, a numerical model is developed in order to support the optimisation of the machining process regarding the transition between ductile and brittle material removal. The simulations are performed with an GPU-accelerated in-house developed code using mesh-free methods which easily handle large deformations while classic methods like FEM would require intensive remeshing. The Johnson-Cook flow stress model is implemented and used to evaluate the applicability of a model for ductile material behaviour in the transition zone between ductile and brittle removal mode. The simulation results are compared with results obtained from single grain scratch experiments using a real, non-idealised grain geometry as present in the diamond wire sawing process. [ABSTRACT FROM AUTHOR]

Due to their excellent physical and mechanical properties, third-generation super hard semiconductor materials (such as SiC, GaN) are widely used in the field of microelectronics. From the crystal bar to electronic devices, slicing is the first machining procedure that directly affects the subsequent process. Fixed diamond wire saw has been widely used in cutting hard and brittle materials. However, the diamond grits of wire saw are bonded through the binding agent's mechanical embedding that slicing super hard crystal is very difficult and inefficient. In order to improve the slicing efficiency, it is necessary to improve the holding strength and wear resistance of the diamond wire saw. The electro-spark deposition (ESD) process can form metallurgical bonding between metal materials at low heat input. The holding strength and wear resistance of the diamond wire saw can be effectively improved. In this paper, the mechanism of the manufacturing process of ESD diamond wire saw (ESDDWS) is introduced, and the conditions of the manufacturing process of ESDDWS are put forward. A model of the surface heat source of saw wire is established considering the wire shape. The transient thermal analysis of the single discharge of ESDDWS is carried out in ANSYS, and the effect of material compaction on material physical properties is considered. According to the simulation results, the parameter range of the manufacturing process of ESDDWS is predicted. The predictions agreed with experiment observation. [ABSTRACT FROM AUTHOR]

• The microsurface-sphericizing textures were realized on the diamond wire sawn (DWS) multi-crystalline (mc) wafers by the combination of metal-assisted chemical etching and rounding etching process. • The microsurface-sphericizing texture was helpful in reducing surface recombination and improving the electrode filling, thereby improving the electrical performance of the cells and modules. • The values of the open circuit voltage (Voc), the filling factor (FF) and the cell-to-module (CTM) loss of the cells and modules were improved with the microsurface-sphericizing process. The combination processes of metal-assisted chemical etching (AgNO 3 + HF + H 2 O 2) and rounding etching (HNO 3 + HF + H 2 O) were used for the texturization of diamond wire sawn (DWS) multi-crystalline silicon (mc-Si) wafers. The evolution of texture structure on the DWS mc-Si wafers was investigated in detail. The chemically microsurface-sphericizing (CMS) textures, which were nearly smooth spherical structure with a size of approximately 2–3 μm, were fabricated successfully on the DWS mc-Si wafers with the combination processes. Compared with the conventional metal-assisted chemical etching (MACE) textures, the CMS textures were improved on surface recombination and the filling of electrode, thereby boosting the electrical performance of the solar cells and the cell-to-module (CTM) loss at the module end. These CMS textures resulted in an increase in the output power of the photovoltaic module by 0.047 W per cell. The fabrication of these CMS textures may be easily scaled up in the photovoltaic production line. [ABSTRACT FROM AUTHOR]

KDP crystal is an important functional crystal material used in the fields of laser frequency conversion. Slicing is the first process of KDP crystal processing and the KDP crystal is usually sliced by the diamond wire saw. As KDP crystal is an anisotropic material, the properties of KDP contact with different diamond grits on the diamond wire saw during slicing would be different. The anisotropic properties may lead to the deviation of the diamond wire saw in the thickness direction and form the surface shape deviation of slice. The surface shape deviation would affect the amount of material to be removed and the accuracy of crystal positioning. The commonly used crystal planes of KDP crystal are the (001), the double-frequency, and the triple-frequency crystal plane. In this paper, a model of diamond wire saw considering the anisotropy of KDP crystal is established to obtain the sawing forces, while the anisotropic properties of KDP crystal used in slicing are obtained through coordinate changes. The obtained sawing forces are then applied to the diamond wire saw to obtain the surface shape deviation. Besides, the influence of the tension force on the surface shape deviation is also considered. Based on the established model, the variation rule of surface shape deviation with the feed angle of diamond wire saw is obtained. Results in this paper can reduce the surface shape deviation of slice caused by the anisotropic properties of KDP crystal. [ABSTRACT FROM AUTHOR]

• A mathematical model of diamond wire sawing was established. • The numerical calculation of the sawn SSD in slicing silicon wafers was carried out. • The effect of process and saw wire parameters on critical speed ratio was analyzed. • The critical speed ratio was predicted when generating a crack-free wafer surface. At present, diamond wire sawing technology has been widely used in slicing photovoltaic polysilicon. Improving the surface quality of the slices to obtain a sawn surface without microcrack damage can greatly increase the fracture strength of polycsilicon wafers and reduce the cost of wet black silicon texturing, which is beneficial to improve the final photoelectric conversion efficiency of solar cells. In this paper, a mathematical model of diamond wire sawing was established based on the machining mechanism of brittle material removal and surface generation, and the numerical calculation of the sawing process was carried out. The validity of the model was verified by sawing experiments. The critical ratio of workpiece feed speed to saw wire movement speed was obtained when generating a crack-free slice surface under the combination of different process parameters and saw wire parameters. Based on the established theoretical model of sawing, the influence of saw wire movement speed, abrasives density and abrasives size on the critical speed ratio was analyzed, and the critical speed ratio (CSR) corresponding to the finer diameter wire and the higher wire speed which will be gradually applied in industry in the future was analyzed. The research results show that it is more conducive to obtaining a crack-free sawn surface by reducing the workpiece feed speed or increasing the saw wire movement speed, and the workpiece feed speed has a greater impact on the sawn surface quality. The CSR will slightly decrease within a small change range when increasing the saw wire movement speed. Increasing the density of abrasives on the saw wire surface within a certain range or decreasing the abrasives size is more inclined to obtain a crack-free sawn surface. The CSR will decrease slightly in a small range when decreasing the abrasives density or increasing the abrasives average size. [ABSTRACT FROM AUTHOR]

Sawability of diamond wire saw is a cost-sensitive parameter in natural stone quarries that affects directly the production planning and equipment selection. The present study intended to investigate the effect of rock properties on sawability of diamond wire saw in granite quarries by considering the cutting rate and unit wear as the main sawability criteria. Hourly cutting rate of stone and unit wear of diamond impregnated beads of diamond wire saw were measured during the stone sawing process in 9 granite quarries. Moreover, physico-mechanical rock properties were determined in the laboratory. Statistical regression models were built to quantitatively analyze the effect of individual rock property on the cutting rate and unit wear. Further, the principal component analysis (PCA) and best subset regression with Bayesian information criterion (BIC) were performed in order to determine the combined effect of most influential rock properties on sawability. Valid for all tested granites, the experimental results indicated that the tensile strength, abrasivity, and brittleness are the most influential rock properties for the prediction of stone cutting rate, whereas compressive strength, elasticity, and abrasivity are dominant for prediction of unit wear of diamond beads. [ABSTRACT FROM AUTHOR]

Based on a traditional acid etch system (i.e., HNO3/HF), a complex texture comprising microscale and submicroscale structures was produced on the surface of a diamond‐wire‐sawn (DWS) multicrystalline Si (mc‐Si) wafer, upon whose surface it is typically difficult to form an effective texture for suppressing the reflection of incident light. Immersing the as‐cut wafer into an HF/HNO3/AgNO3 solution introduced a large number of artificial defects onto the wafer surface. A subsequent HNO3/HF etch induced a micron texture expanded from the original DWS‐induced damage as well as a submicron texture converted from the artificial defects. The multiscale textured DWS exhibited a reflectivity of ~19%, which is much lower than the reflectivity after only an HNO3/HF etch (~28%). Therefore, the solar cell performance was improved owing primarily to improved optical antireflection and surface passivation. The method is simple and can be easily scaled up into the in‐line texture process. [ABSTRACT FROM AUTHOR]

Fig. 1. SEM images of silicon wafers processed in Step1 (saw damage removal): (a) Additive Group; (b) local area of Control Group without white spots; (c) white spots of Control Group. (d) and (e) show the SEM images of silicon wafer processed after Step 5: (d) Additive Group; (e) Control Group. • An additive was adopted to remove the damage layer on the surface of DWS mc-Si wafer. • The problem of white spots and stains on the wafer in mass production is eliminated. • An efficiency of 19.49% was achieved for multi-crystalline black silicon solar cells. The first step of preparing black silicon solar cells by Ag metal-assisted chemical etching method (Ag-MACE) is to remove the saw damage layer on the surface of diamond wire saw multi-crystalline silicon wafers. The usual way to do this is with a hot solution of KOH. However, the surface of silicon wafers processed in large quantities in this way will have many white spots and stains. These white spots and stains are the saw damage layer that have not been removed cleanly. They affect not only the appearance of the solar cells, but, most importantly, the subsequent uniform deposition of silver nanoparticles on the silicon wafers. An additive containing cyclodextrin and lignosulfonate has been developed in this work. This can remove effectively the saw damage layer and eliminate the white spots and stains on the surface of the silicon wafer. So as to improve the appearance of silicon wafer and make silver nanoparticles uniformly deposited on the surface of the whole silicon wafer. This additive has been proved to be very useful in improving solar cell efficiency, raising parallel resistance and reducing reverse leakage current and so on. Eventually, mass-produced solar cells made by Ag-MACE with this additive have a maximum efficiency of 19.49%, which is 0.46 percent absolutely higher than that without the additive. [ABSTRACT FROM AUTHOR]

Assessment of wear rate is an inseparable section of the saw ability of dimension stone, and an essential task to optimization in the diamond wire saw performance. This research aims to provide an accurate, practical and applicable model for predicting the wear rate of diamond bead based on rock properties using applications and performances of intelligent systems. In order to reach this purpose, 38 cutting test results with 38 different rocks were used from andesites, limestones and real marbles quarries located in eleven areas in Turkey. Prediction of wear rate is determined by optimization techniques like Multilayer Perceptron (MLP) and hybrid Genetic algorithm –Artificial neural network (GA-ANN) models that were utilized to build two estimation models by MATLAB software. In this study, 80% of the total samples were used randomly for the training dataset, and the remaining 20% was considered as testing data for GA-ANN model. Further, accuracy and performance capacity of models established were investigated using root mean square error (RMSE), the coefficient of determination (R2) and standard deviation (STD). Finally, a comparison was made among performances of these soft computing techniques for predicting and the results obtained indicated hybrid GA-ANN model with a coefficient of determination (R2) of training = 0.95 and testing = 0.991 can get more accurate predicting results in comparison with MLP models.

Lower warp is required for the single crystal silicon wafers sawn by a fixed diamond wire saw with the thinness of a silicon wafer. The residual stress in the surface layer of the silicon wafer is the primary reason for warp, which is generated by the phase transitions, elastic-plastic deformation, and non-uniform distribution of thermal energy during wire sawing. In this paper, an experiment of multi-wire sawing single crystal silicon is carried out, and the Raman spectra technique is used to detect the phase transitions and residual stress in the surface layer of the silicon wafers. Three different wire speeds are used to study the effect of wire speed on phase transition and residual stress of the silicon wafers. The experimental results indicate that amorphous silicon is generated during resin bonded diamond wire sawing, of which the Raman peaks are at 178.9 cm−1 and 468.5 cm−1. The ratio of the amorphous silicon surface area and the surface area of a single crystal silicon, and the depth of amorphous silicon layer increases with the increasing of wire speed. This indicates that more amorphous silicon is generated. There is both compressive stress and tensile stress on the surface layer of the silicon wafer. The residual tensile stress is between 0 and 200 MPa, and the compressive stress is between 0 and 300 MPa for the experimental results of this paper. Moreover, the residual stress increases with the increase of wire speed, indicating more amorphous silicon generated as well.

The market share of monocrystalline silicon (mono-Si) solar cells is increasing year by year due to high efficiency. The first process of producing silicon-based solar cell substrate is to saw silicon brick into wafers with a diamond wire saw. In order to reduce the production cost, the size and thickness of silicon wafers are becoming larger and thinner, and the width of the sawing kerf is becoming smaller and smaller. During the slicing process of the diamond wire saw, the cooling liquid will create a liquid layer between adjacent silicon wafers due to the capillary phenomenon. When the bending stiffness of silicon wafers is not enough to resist the capillary force generated by the liquid layer, the silicon wafers will adhere together and bend to produce bending stress. The coupling effect of bending stress and sawing stress affect the fracture probability of silicon wafers. In this paper, the coupling stresses of bending stress, sawing thermal stress and sawing mechanical stress of the silicon wafer during the sawing process were calculated by the finite element analysis method. The influences of the wafer size characteristics, the kerf width and the process parameters on coupling stress were analyzed. Based on the Weibull probability function, the fracture probability of wafers under maximum coupling stress was predicted. The results show that the probability of wafer fracture increases with the increase in size and the reduction of thickness, and decreases with the decrease in kerf width. The increase in diamond wire speed and feed speed will increase the wafer fracture probability. The research results provide theoretical guidance for understanding the wafers fracture in the sawing process, and provide a theoretical basis for the process optimization of sawing large-size and ultra-thin wafers. [ABSTRACT FROM AUTHOR]

The wear rate of diamond wire saw plays a vital role in the performance of sawing process. Predicting the sawing performance is very important in the production’s cost estimation and planning of the dimension stone quarries. In this research, an adaptive neuro-fuzzy inference system (ANFIS) is applied to estimate the wear rate of diamond wire saw under uncertain processes; hence, indirect prediction in ANFIS is carried out using subtractive clustering method (SCM) and fuzzy c-means clustering method based on four effective rock properties, such as Shore hardness, Schimazek’s F-abrasivity, uniaxial compressive strength and Young modulus. For this purpose, 38 rock samples were selected to test the proposed model from Turkey quarries. The results of indirect prediction indicated that the best performed model was related to ANFIS-SCM with highly acceptable degrees of accuracy 0.998 and 0.59 for R2 of the train and test data sets, respectively. In addition, group method of data handling type of neural network is used to assess the factors influencing the wear rate of the diamond wire saw. A sensitivity analysis was performed on the laboratory test results of studied rocks using three methods. In comparison to the existing models, the estimated results showed that a satisfactory performance could be obtained using the proposed ANFIS-subtractive clustering method. [ABSTRACT FROM AUTHOR]

Slicing is the initial procedure in silicon wafer manufacturing process. The cost of slicing process is about 30% of the total cost of chip fabrication. The effective approaches to decrease slicing cost are to reduce the slicing kerf loss and to decrease the thickness and breakage ratio of sliced wafer. The resin-bonded diamond wire saw has the advantages of uniform of abrasive protrusion height and the manufacturing process less impact on the core wire strength. It is expected to achieve a narrow kerf and ultra-thin wafer slicing of silicon crystal ingot with resin-bonded diamond wire saw. The aim of this paper is to develop high-performance resin-bonded diamond wire saw. Based on the analysis of fabrication process of resin bond diamond wire saw, the device for resin-bonded diamond wire saw manufacturing is developed. The mold in the fabrication device ensures the consistency of the wire saw outer diameter and the uniform of abrasive protrusion height. A test device for constant force feed slicing is developed for the slicing performance evaluation of resin-bonded diamond wire saw. The components of the coating layer materials of resin-bonded diamond wire saw are investigated via orthogonal test. Choosing the material removal rate, wire saw wear rate, coating layer binding force, and sliced surface roughness as evaluation indexes, the performance of developed resin-bonded diamond wire saw is evaluated. The optimal component ratio of the coating layer materials of resin-bonded diamond wire saw is obtained, and the verification test of the optimal component ratio of the coating layer materials is performed. The results of this paper are useful for the development of smaller-diameter diamond wire saw and high-quality slicing of optoelectronic crystal ingot. [ABSTRACT FROM AUTHOR]

Ultrasonication vibration as the pretreatment process, combined with wet acid etching, was utilized for the texture of diamond wire sawn (DWS) multi-crystalline silicon wafers. The SiC particles in the ultrasonic device were imposed for cavitation-generating blasting action on the DWS wafers surfaces. The blasting action exceeding 5 min can remove saw marks and smooth zones on the DWS wafer surfaces by producing new pits. After wet acid etching，the texture morphology of ultrasonically pretreated DWS mc-silicon wafers was quite uniform as compared to wet-textured as-cut DWS mc-silicon wafers, similar to wet-textured slurry wire saw(SWS) mc-silicon wafers. Light reflectivity tests confirmed the beneficial effect of the ultrasonic pretreatment of DWS mc-silicon wafers. This technique could be a potential solution to the texturization problem of DWS mc-silicon wafers. [ABSTRACT FROM AUTHOR]

Sapphire crystal is widely used as Light Emitting Diode (LED) substrate and window materials for electronic devices. During the sawing process of sapphire crystal, the wear of saw wire leads to different sawing performance. In this paper, the abrasives wear state, the diameter change and wear rate of the saw wire, the change of surface morphology and surface roughness (SR) of as-sawn sapphire crystal wafer during the whole service cycle of saw wire under typical sawing parameters were analyzed, and the stable service period of diamond saw wire was determined. Further, sawing experiments were conducted during the stable service period of diamond saw wire, and the effects of sawing parameters within the industrial production on the as-sawn sapphire crystal wafers surface characteristics were studied. The results show that within range of sawing parameters adopted in this paper, the abrasives mainly remove the material in a brittle mode, and the SR of the as-sawn wafers decreases as the saw wire speed increases (from 1000 m/min to 1600 m/min), and the as-sawn wafer surface morphology is improved. As the specimen feed speed increases (from 0.05 mm/min to 0.5 mm/min), the SR increases, and the consistency of the as-sawn wafer surface morphology deteriorates. • The sawn wafer surface in the early service stage of saw wire is relatively poor. • Better wafer surface quality is achieved in the middle service stage of saw wire. • Abrasives on saw wire surface are worn flat or fall off in its later service stage. • Higher wire speed or lower feed speed can lead to better wafer surface quality. [ABSTRACT FROM AUTHOR]

In order to improve the performance of solar cells and reduce their manufacturing costs, monocrystalline silicon wafers used for manufacturing solar cells are developing towards larger sizes and ultra-thin thickness, and the diameter of diamond saw wires used to cut silicon wafers is also continuously decreasing. These aspects cause uneven thickness and lager thickness variation (TV) of the as-cut wafer during slicing process. The reason of uneven thickness was analyzed from the point of liquid bridge with capillary force between the saw wires in this paper. The mechanical equilibrium equation between the liquid bridge and the saw wires was established based on the Young-Laplace equation, and the theoretical model of the as-cut wafer thickness was derived during the sawing process. The effect of the saw wire tensioning force, span, the diameter of the core wire and the wetting angle of coolant on the as-cut wafer thickness variation was analyzed based on the model. The results show that the increase in the saw wire tensioning force, the core wire diameter and the wetting angle of coolant improved the thickness accuracy and reduced the thickness variation of the as-cut wafer. And the increase in the saw wire span reduced the thickness accuracy and increased the thickness variation. The research results of this paper provide the mechanism analysis for the thickness variation of the ultra-thin wafer during the slicing process. It is of great significance to produce the ultra-thin photovoltaic silicon wafers with the fine saw wire in the future. • Mechanism of ultra-thin Si wafers TV in fine diamond wire cutting is analyzed. • Mechanical equation between liquid bridge capillary force and saw wire is founded. • Theoretical model of as cut wafer thickness during the sawing process is established. • Influence of various parameters on the TV of as-cut Si wafers is revealed. • Measures to improve the thickness consistency of as cut wafer are proposed. [ABSTRACT FROM AUTHOR]

Predicting the wear rate of diamond beads in the diamond wire sawing process is one of the most important factors in the optimized design and cost estimation of quarrying. This paper aims to predict the wear rate of diamond beads as one of the principal performance criteria in dimension stone quarrying. Saw operating parameters and mechanical and physical properties of rock are the most effective factors on diamond bead wear. In the same working conditions (at constant operating parameters), the wear rate of diamond wire saw is strongly affected by the production rate, and the characteristics of rock. In this study, the uniaxial compressive strength, Schmiazek abrasivity factor, Mohs hardness, and Young's modulus were selected as the main physical and mechanical properties of rock. The 11 types of igneous rocks were cut in the laboratory using a diamond wire saw and a fully instrumented cutting platform. During the cutting process, the wear rate of diamond beads were determined after each cutting test. The wear rate of diamond bead and rock characteristics were evaluated using simple and multiple curvilinear regression analysis, and prediction models were developed. The developed models were validated by considering the t-test, F-test, correlation coefficient and the plots of predicted versus actual values. The results indicated that the wear rate of diamond beads can be reliably predicted using the developed model. [ABSTRACT FROM AUTHOR]

During recent years, diamond wire sawn (DWS) multicrystalline silicon (mc-Si) wafers have been widely used to reduce the production costs; however, these wafers need additional process treatments such as reactive ion etching (RIE) or metal-catalysed chemical etching (MCCE) to form a surface with relatively low reflectivity. Although the absolute power conversion efficiency of the solar cell could be improved by 0.3-0.5% through the introduction of such surface treatments, the production costs would also be increased. In this study, an improved production-scale acidic texturization with additives is used to texture the surfaces of DWS mc-Si wafers, giving a similar weighted averaged reflectance (WAR) of 19.69% as slurry-cut wafers. The effect of the texturization process on the surface morphology, WAR and performance of the DWS mc-Si cells is discussed. [ABSTRACT FROM AUTHOR]

In this study, the variation in diamond wire tension during the reciprocating wire-winding machining process is investigated to improve the cutting stability and machining precision of a reciprocating winding diamond wire saw. Furthermore, the main causes of wire tension variation are analyzed, a tension control method using a PI (proportional-integral) regulator is proposed, and a wire tension detection and control mechanism is developed to solve the problem of tension variation during the machining process. The performance of this mechanism is verified through experiments, in which polycrystalline silicon materials are cut. Experimental results show that the designed mechanism can effectively mitigate tension instability during the reciprocating wire-winding machining process, control the wire tension fluctuation within 0.6 N, and significantly improve cutting efficiency, cutting surface roughness, and machining dimension accuracy. [ABSTRACT FROM AUTHOR]

Wire deflection affects the shape precision of workpiece during the profile cutting process with diamond wire saw. This study proposes a method for solving this problem using wire deflection detection, called light projection method. This method is based on the space position of the diamond wire. This research also analyzes the effects of wire deflection on shape precision, develops a detection and control device that allows feedback control according to the change in wire projection position, judges the wire position change, and uses this device to perform validation tests with polycrystalline silicon materials. The test shows that this detection and controlling device can effectively control the wire deflection phenomenon in the process of diamond wire cutting process. The roundness of a polysilicon with 20 mm thickness and φ20 mm diameter can be controlled within 0.05 mm, enabling significant improvement in the cutting shape precision and cutting stability. [ABSTRACT FROM AUTHOR]

The dominant method to cut brittle materials is using fixed-abrasive wire saw slicing. This paper investigates the mechanism of pneumatic conveying diamond grains in the process of manufacturing diamond wire saws. Based on the theories of gas–solid two-phase flow, a mathematical model is developed for the process of diamond grains embedding into the metal-covered wire with resin. The model is divided into five stages for insights into the action of diamond grains. Then the embedding rate is calculated. From the experiments, we can compare the theoretical analysis and practical results of the embedding depth of diamond grains under different pressures in a three-dimensional microscopy experimental setup. With the present mathematical model, it is feasible to produce diamond wires by the method of pneumatic conveying diamond grains with the help of this study. [ABSTRACT FROM PUBLISHER]

• The effect of industrial process parameters on SSD of DW sawn sapphire was studied. • A mathematical model for calculating SSD of DW sawn sapphire was proposed. • The effect of DW abrasive parameters on sawn sapphire SSD was studied. Sapphire crystals are widely used as window materials for infrared emitting devices, high intensity lasers, optical elements and microelectronic substrates due to the excellent material properties. The subsurface microcrack damage produced by diamond wire saw when cutting sapphire crystal is an important indicator of the cutting quality. In this paper, diamond wire sawing experiments were conducted within the industrial production processing parameters to investigate the as-sawn sapphire crystal wafers subsurface microcrack damage depth (SSD), and a numerical calculation model was established to predict the SSD based on the analysis of the scratching stress field of single abrasive. The effects of the saw wire speed and specimen feed speed, saw wire parameters on SSD were predicted. The results show that, within the parameters studied in this paper, the material was removed in brittle mode, increasing the saw wire speed (from 1000 m/min to 1600 m/min) and reducing the specimen feed speed (from 0.5 mm/min to 0.05 mm/min) can reduce the sapphire as-sawn wafers SSD, reduce the size of brittle tear-shape edge breakage, the number and size of brittle pits on the as-sawn wafer surface are reduced and the surface morphology consistency is improved. Increasing the abrasive density and reducing the abrasive size can reduce the SSD. The study results provide a reference for the reasonable matching of sawing process parameters and saw wire parameters in industry. [ABSTRACT FROM AUTHOR]

• An analytical model of minimum sawing thickness of silicon wafer is based on Kirchhoff's thin plate theory. • The analytical model is verified by the finite element simulation. • The experiment of the minimum thickness of diamond wire saw cutting monocrystalline silicon wafer is accomplished to validate the theory. Diamond wire sawing is one of the key technologies in solar cell manufacturing process and semiconductor chip manufacturing process. The thinned of silicon wafer has become a development trend of semiconductor industry, and the reduction of silicon wafer thickness can improve the material utilization and reduce the manufacturing cost. Therefore, the minimum thickness analytical model of diamond wire saw cutting monocrystalline silicon wafer is proposed in this paper to study the processing mechanism of minimum thickness of monocrystalline silicon wafer. Firstly, based on the Kirchhoff's thin plate theory, the theoretical equation of the maximum internal stress of single silicon wafer and the sawing thickness of the silicon wafer is derived from the sawing force model. Combined with the Mohr's strength theory, the analytical model of minimum sawing thickness of monocrystalline silicon wafer is established. Then, the analytical model is verified by the finite element simulation. The average error between the simulation results and the calculation results of the analytical model about the minimum sawing thickness of silicon wafer is 9%. Finally, the monocrystalline silicon sawing verification experiments are conducted under some groups of processing conditions. The experimental results show that the minimum sawing thickness of the silicon wafer decreases with the increasing axial speed of the wire saw, increases with the increase of the feed rate of the wire saw, and decreases first and then increases with workpiece speed becoming large. The average error of the experimental results and the calculation results of the analytical model of the wafer minimum sawing thickness is 7.4%, which verifies corrections of the analytical model. [ABSTRACT FROM AUTHOR]

A vapor etching texturization method based on vapors generated from HF-HNO 3 solution has been developed previously for texturization of diamond wire sawn multicrystalline silicon wafers. The present work is a further study to understand the mechanisms of the process. The vapor etching experiment of a diamond wire sawn multi-crystalline wafer was carried out, in which the topography, average etch depth by weight loss, light reflectivity and roughness were tracked. Based on the observations, a discussion of the mechanisms and their relation to the topographical evolution was presented. The conclusions are that, the key mechanism for the VE texturization of diamond wire sawn multi-crystalline silicon wafers is forming of micro-droplet of the liquid phase and the erosive attack by them. The droplets may be formed in evaporation of previously formed liquid films, which is a result of massive condensation of the vapor onto the initially cold wafers, or in condensation of the vapor onto warmer wafers or existing droplets. The exothermic etching reaction leads to a well self-regulating evolvement of the wafer temperature. More liquid phase on the wafer causes more intensive reaction, and hence higher wafer temperature, that in turn causes evaporation of the liquid phase; while this slows down the reaction, and lowers the temperature, that in turn brings more condensation of the liquid phase from the vapor. Such a temperature evolvement creates good opportunities for formation of the micro-droplets of the liquid phase. [ABSTRACT FROM AUTHOR]