Yu Fei Gao

Study on Removal Mechanism of Fixed-Abrasive Diamond Wire Saw Slicing Monocrystalline Silicon

The physical model of fixed-abrasive diamond wire-sawing monocrystalline silicon was founded to analyze the elastic deformation of the wire, supposing that every grit was connected to the surface of the wire by a spring. Ignoring lateral vibration of the wire, the geometrical model of wire-sawing was founded; the average cut depth of single grit was calculated theoretically. Based the indentation fracture mechanics and investigations on brittle-ductile transition of machining monocrystalline silicon, the removal mechanism and surface formation was studied theoretically. It shows that in the case of wire-sawing velocity of 10m/s or higher, infeed velocity of 0.20mm/s and diamond grain size of 64μm or smaller, the chip formation and material removal is in a brittle regime mainly, but the silicon wafer surface formation is sawed in a ductile regime. The size of the abrasives, the wire-saw velocity and infeed velocity can influence the sawing process obviously.

Relationship between the Grit Cut Depth and Process Parameters in Electroplated Diamond Wire Sawing KDP Crystal

A wire-saw cut KDP crystal geometrical model was founded and a mathematical model was established to calculate the grit average cut depth, based on indentation fracture mechanics theory(IFMT). The relationship between the grit cut depth and wire saw process parameter was analyzed theoretically. The research results indicate that there exists an approximate monotone increasing non-linear correlation between grit average cut depth and the ratio i value of crystal feed speed and wire speed. By increasing the wire speed and crystal feed speed accordantly, the value of i can be maintained invariable, however, this way can simultaneously bring higher machined surface quality and machining efficiency.

Analysis of Grit Cut Depth in Fixed-Abrasive Diamond Wire Saw Slicing Single Crystal Silicon

A mathematical model to calculate the grit average cut depth in wire sawing single crystal silicon was founded. So the grit average cut depths were calculated theoretically by choosing different process parameters, and influences of process parameters on grit cut depths of slicing silicon crystal were analyzed. Analysis results indicate that the grit average cut depth relates to the silicon mechanical properties, grit shape and size, wire speed and ingot feed speed, etc. And there is a monotone increasing non-linear correlation between grit average cut depth and the ratio i value of ingot feed speed and wire speed, when the i value is lower, the average grit cut depth is lower.

Experimental Investigation on Brittle-Ductile Transition in Electroplated Diamond Wire Saw Machining Single Crystal Silicon

Based on reciprocating electroplated diamond wire saw (REDWS) slicing experiments, a study on REDWS machining brittle-ductile transition of single crystal silicon was introduced. The machined surfaces and chips were observed by using Scanning Electron Microscope (SEM), and some experimental evidences of the change of material removal mode had been obtained. The experimental results indicate there is a close relationship between material removal mode and the ratio r value of ingot feed speed and wire speed, through controlling and adjusting the r value, the material removal mode can be complete brittle, partial ductile and near-ductile removal.

Investigation of Subsurface Damage Depth of Single Crystal Silicon in Electroplated Wire Saw Slicing

Based on reciprocating electroplated diamond wire saw slicing single crystal silicon experiments, a bonded interface sectioning technique was used to measure the silicon subsurface damage (SSD) depth, and the influences of wire saw speed and feed speed on silicon SSD were studied. Moreover, based on the indentation fracture mechanics (IFM) theory, a theoretical model of relationship between SSD and surface roughness (SR) was established for predicting the SSD depth by measuring the SR. The results indicate that SSD depth decreases with the wire saw speed increase and feed speed decrease, within the range of experimental technical parameters. There exists monotone increasing non-linear correlation between SSD depth and SR (Rz) in wire saw slicing single crystal silicon, that is, SSD－SR+χSR3/4. And the experimental measure values coincide with the theoretical prediction values comparatively, therefore, the theoretical model can be used for predicting SSD depth rapidly, expediently and accurately.

Development of the Manufacture Equipment for Resin Bonded Diamond Abrasive Wire Saw

This paper introduces the structure of the resin bonded abrasive wire saw manufacture equipment. The equipment can complete the process of the wire saw production, including uncoiling wire, cleaning wire, binder coating, Pre-curving and coiling wire. Wire saw are manufactured successfully by this equipment in the manufacture experiment. The quality of the wire saw was examined by SEM. The average slicing ability of the wire saw is 205 mm2 per meter in the experiment of KDP crystal slicing.

Simulation and Prediction Studies on Harden Penetration Depth of AISI 5140 Alloy Steel in Surface Grinding

The grinding heat is utilized to induce martensitic phase transformation and strengthen the surface layer of AISI 5140 alloy steel by raising surface temperature higher than austenitic temperature and cooling quickly. The grinding temperature field is simulated by using finite element method (FEM). Then, the hardness penetration depth (HPD) is predicted from the temperature history and martensitic phase transformation conditions in surface grinding. The experiments of different grinding parameters are performed in surface grinding lathe. The hardness and hardness penetration depth of work piece surface layer are measured to validate the simulation and prediction. This method can be used to predict the HPD and optimize the grinding parameters forwardly.

Wire Tension Force Variable Universe Fuzzy Control in Fixed Abrasive Wire Saw Manufacturing

The structural characteristics of the tensioning device in the wire saw manufacturing equipment is introduced. Based on the characteristic of the strainer, the principle of variable universe fuzzy control is adopted to deal with the controlling objects. The design of two stage fuzzy controller and its parameters are discussed. The system simulation shows that the control scheme can make the tension within the stable range.

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 Numerical Analysis on Action Mechanism of Slurry in Free Abrasive Wiresaw Slicing

Free abrasive wiresaw technology is the main method in slicing monocrystalline silicon wafers. The mathematical model of hydrodynamic action in the process of the free abrasive wiresaw slicing was founded, displacement caused under distributed radial load of every node on the wire is embodimented through self-compliance influence coefficient, which is beneficial to found the film thickness equation. The distributions of hydrodynamic pressure and film thickness in the free abrasive wiresaw slicing process are yielded by using the finite difference numerical methods to solve the two-dimension Reynolds equation. The results show that the minimum film thickness increases with the increase of wire speed, and slurry viscosity, while decreases with the increase of wire bow angle. The film thickness is greater than the average abrasive size so that the abrasives float in the slurry when the size of abrasive is small enough.