Fixed-abrasive Wire Research Articles

Study on the subsurface microcrack damage depth in electroplated diamond wire saw slicing SiC crystal

At present, the fixed-abrasive wire saw machining technology is widely used in the slicing process of SiC single crystal. And the subsurface microcrack damage depth of wire sawn SiC wafer is an important quality control parameter. In this paper, experimental and numerical analysis of the subsurface microcrack damage depth of single-crystal SiC in wire sawing is presented. A finite element model (FEM) which was used for simulation and calculation of subsurface microcrack damage depth in wire saw slicing SiC crystal wafer was established. The variations of maximum principal stress and stress change rate of sawn crystal and slice in wire sawing were analyzed, and the validity of the FEM was verified by sawing experiment. Further, microcrack damage depths under different ingot feed speeds and wire speeds were predicted and the influence of process parameters on microcrack damage depth was discussed. Research results show that the microcrack damage depth values of simulation are lower than the experimental measurement, but with a consistent change trend of a relative error is less than 15.92%. The subsurface microcrack damage depths of sawn wafer decrease with the increase of wire speed and decrease of feed speed. The research results can be helpful to develop precision and high quality slicing technology of SiC single crystal.

A finite element analysis of sawing stress in fixed-abrasive wire saw slicing KDP crystal

Potassium dihydrogen phosphate (KDP) crystal is the preferred nonlinear optical crystal used in pockels cell and frequency multiplier. Slicing machining is the first process for KDP crystal, which has an important effect on the yield rate. However, KDP crystal is easy to crack when sliced due to the maximum tensile stress. This paper presents the finite element analysis of sawing stress in fixed-abrasive wire saw slicing KDP crystal. The finite element model of wire sawing KDP crystal is found, and the sawing forces are analyzed and loaded to the cutting kerf that are simplified as the normal sawing pressure p contrary to the workpiece feed direction and the tangential sawing pressure q along the wire moving direction, based on the analysis of fixed-abrasive wire saw cutting mechanism. The dynamic distribution and variation rule of the sawing stress and the coupling of sawing stress with crystal initial internal stress have been analyzed when slicing the (001) crystal plane optical device, and the critical initial internal stress of the KDP crystal to avoid cracking in wire saw cutting is discussed. Numerical simulation results show that the sawing stress for cutting KDP crystal without initial internal stress is a low-stress machining way, but a larger tensile stress produces due to the initial stress gathering in the kerf coupled with the low sawing stress. A greater crystal initial internal stress can lead to the more intense concentration of sawing stress; it suggests that the initial internal stress inside the sawed KDP crystal should be less than 2.294 MPa. The research results help to further understand the sawing stress field distribution and change in the process of slicing KDP crystal.

A pneumatic conveying method for the manufacturing of ultraviolet curing diamond wire saws

ABSTRACTThe 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.

Experiment study on electroplated diamond wire saw slicing single-crystal silicon

This paper conducted the slicing experiments of single-crystal silicon using a reciprocating electroplated diamond wire saw. The machined wafer topography and wire wear were observed by using scanning electron microscope (SEM). The influences of process parameters and cutting fluids on single-crystal silicon wafer surface roughness (SR), subsurface micro-crack damage (SSD) depth, total thickness variation (TTV) and warp were investigated. The bonded interface sectioning technique was used to examine the cut wafers SSD depth. Study results show that a higher wire speed and lower ingot feed speed can produce lower wafer SR and SSD; the lower warp of wafer needs lower wire speed and ingot feed speed; and low wafer TTV can be obtained by an appropriate matching relationship between wire speed and ingot feed speed. The synthetic cutting fluid has a better total effect to improve the wafer quality. The pulled-out of diamond abrasives is the main wear form of wire, which indicates that more research on improving the abrasives retaining strength on wire surface should be investigated in fixed-abrasive wire manufacturing process, in order to improve the wire life and wire saw machining process.

Mechanism and Motion of Semifixed Abrasive Grit for Wire-Saw Slicing

The currently dominant method in the production of wafers is to use slurry wire-saw slicing. This paper reports a new wire-saw slicing technology, namely, semifixed abrasive wire-saw slicing. The traditional smooth wire is replaced by a patterned wire with a textured surface that can help the wire carrying the abrasives. It aims to improve the number of transient fixed abrasives in the machining process. Transient fixed abrasives can produce “scratch-indenting” processes that are similar to fixed-abrasive wire slicing thereby improving the efficiency of the wire-saw cutting. This study focuses on the behavioral mechanics of the abrasive grits in the slurry during the slicing process. The dynamic images of the movement of abrasive grits in the slicing process are obtained by a high-speed camera. At the microlevel, using statistical methods, the behavioral mechanics of the abrasive grits are investigated by changing the slicing parameters. The results contribute toward a more intuitive and profound understanding of the principle of free-abrasive wire sawing.

Manufacturing of Fixed-Abrasive Polyethylene Wire Saw

Fixed-abrasive diamond wire saw is widely used for slicing semiconductor materials. In this paper, a novel manufacturing method is studied by using polyethylene wire to replace the traditional metallic core wire. A new coating device of ultraviolet-curing for rapidly making diamond wire saw is developed. In terms of tensile strength experiments’ results, a high strength polyethylene multi-strand wire is finally selected as the core wire of the fixed-abrasive wire saws. Experimental results show that the high tensile strength of polyethylene multi-strand wire can satisfy the technical requirements of fixed-abrasive wire saws.

Development Evaluation of Mechanical Properties of Brazed Diamond Wire

Fixed-abrasive wire saw, with its ability to cut hard brittle material, such as silicon ingots, crystals and quartz, has emerged as a leading technology for production in semiconductor and photovoltaic industry. There are some defects in conventional fixed-abrasive wire saw such as significant low holding abrasive ability, low machining efficiency, high running costs, etc. A new fixed-abrasive wire, namely brazed diamond wires have been developed to overcome these problems. In this paper, brazed diamond wire were carried out to braze two different size diamond grits onto two different thin steel wires by using a nickel-based powder as brazing alloy. The mechanical properties of brazed diamond wire were evaluated by tensile and breaking twist experiment. The experimental results showed that the heating in the brazing process has litter influence on the wire mechanical properties. The addition of brazed alloy and diamond grits sharply decreased the wire mechanical properties significantly, both in the tensile strength and breaking twist angle. Bigger diamond grit would make the accumulation of brazed alloy which leaded to the deterioration of diameter consistency of wires.

Study on Electroplated Diamond Wire Saw Development and Wire Saw Wear Analysis

Development of high performance diamond impregnated wire is the key of application for fixed-abrasive wire sawing technology. In this paper, some experimental studies were done for development of electroplated diamond wire saw by employing the bright nickel bath. The wire saw electroplating process was developed, the effects of cathode current density and time at tack-on stage on diamond grits density and adhesion between saw matrix and plating coating were discussed. The wire saw cutting experiments were carried out for analysis the used wire wear using the scanning electron microscope (SEM). The experimental results show the optimum tack-on current density to obtain the wire saw with good abrasive distribution and adhesion is 1.5~2.0A/dm2, and the time of pre-plating, tack-on and buildup is 6, 8~10 and 18min in turn. Diamond wire saw wear includes coating wear and grain-abrasion, and the primary wear form is grits pulled-out.

The Diamond Wire Saw with a Nonmetallic Core

Diamond wire saw is the leading technology for use in cutting hard brittle material. Its smaller kerf and faster cutting time make it replacing the conventional slurry technology for those materials. Turned over the traditional router, this paper presents a novel approach that replaces the typical metallic core with a nonmetallic core, for manufacturing of ultraviolet curing resin fixed-abrasive diamond wire saw (DWS). The experiments show that the diamond wire saw made by this manufacturing method can obtain a good performance as well as taking many other advantages.