Wei Fang Wang

Theoretical Analysis and Uniformity of Trajectories in Lapping Process

A new trajectory and uniformity was studied for single lapping process, kinematic theory analysis trajectories of the workpiece under the mode driven by swing motion. According to the theoretical analysis on lapping trajectory and simulated results, uniformity during swing driven lapping process is better than tranditional lapping process, angle rotation ratio between lapping plate and swing plate has great effect on lapping uniformity, when rotation speed of lapping plate is three times to that of swing plate, best uniformity could be gotten during lapping process.

Statistical Analysis on Lapping Parameters for Sapphire Wafer

Effect of lapping speed, plate material and crystal orientation on material removal rate and surface roughness were investigated by experiments and Taguchi Methods. Experimental results show both materials remove rate and surface roughness could be finished by using sythetic copper lapping plate with w3.5 cubic boron nitride abrasive than that for thin plate. Materials removal rate and surface roughness have no much difference for different crystal orientation as A-plane, C-plane and M-plane with experimental parameter conditions, lapping speed would be recommonded to not over 40rpm.

Methods of Evaluation the Uniformity in the Lapping Process

This paper reviews three methods used to evaluate the uniformity in the lapping process. The first one evaluates the uniformity in lapping process according to studying the uniformity of lapping trajectory. The second one, compared with the measurement pattern based on polar coordinate, explains the advantages of Cartesian -based coordinate pattern in evaluating the lapping uniformity. The last one develops a model to calculate material removal in the lapping process and indicates the uniformity by calculating the material removal. These methods evaluate the uniformity in lapping process from different views, respectively, but each method still has various drawbacks. Therefore, further researches must be carried out to improve the system used to evaluate the uniformity in the lapping process.

Analysis of Ultrasonic System in Acoustic Levitation Polishing

In order to obtain a stable acoustic suspension field, it is essential to select a system of ultrasonic. This paper through Theoretical analysis of a system of ultrasonic, combine the condition of acoustic levitation polishing, to select the ultrasonic generator, ultrasonic transducer and the horn, to provides a good base for obtain a stable acoustic suspension field.

Numerical Simulation of a Novel Bipolar Plate Flow Field of Proton Exchange Membrane Fuel Cell

This paper proposes a novel bipolar plate flow field of PEMFC with the intersectant microstructure. Numerical simulation about both the flow velocity distribution and the pressure distribution for the reactive gas were accomplished according to the model building by Pro/E, grid meshing and boundary condition specifying by Fluent. Compared to traditional serpentine flow fields, the gas pressure difference between the inlet and the outlet of this novel flow field is appropriate to promptly discharge the water produced during the operation of the PEMFC, and the flow velocity of the reactive gas among all the flow field is well-distributed, which assures reactions occurring uniformly in the flow field under the bipolar plate. All the properties of this novel flow field make a great sense to improve the integrated performance of the PEMFC.

3D Finite Element Simulation on the Orthogonal Cutting Processes with Different Commercial Codes

The purpose of this paper is to compare different simulation model of orthogonal cutting process using three different FEM commercial codes as well as with the results of orthogonal experiment. For one thing, element type, boundary condition and friction model between the chip and tool commercial have been compared when the numerical model established in implicit finite element code, Deform3D and the explicit code ANSYS/LS-DYNA and Thirdwave AdvantEdge. For another, main and thrust cutting forces, shear angles, chip thicknesses and contact lengths by three codes are compared with the orthogonal metal cutting experiment by Movahhedy and Altintas.

Numerical and Flow Field Simulation of Acoustic Levitation Polishing

Based on a novel polishing method named as acoustic levitation polishing. Analysis of the basic principles of acoustic levitation polishing. Through the simulation of fluid field in polishing, by the case that in a single or multiple sound source vibration, contrast the flow field of slurry. Analysis of the effect of the movement of slurry in the container to the surface uniformity.

Hydration Polishing of Sapphire

This paper discussed the polishing characteristic of single crystal sapphire (0001) when using 100°C vapor as polishing liquid and cedar wood as polishing pad. Surface roughness and scratch were compared before and after hydration polishing process. For 20 hours hydration polishing, both XRD and surface texture show that sapphire surface was changed in micro-structure and texture, even with minor scratch on the hydration polished surface, surface roughness could be decreased to Rt6.74 in X direction and Rt7.64nm in Y direction, it is about 2 nm surface layer was removed during hydration polishing.

Uniformity of Kinematic Trajectory with Wafer Driving Initiatively in Plane Lapping Process

This paper analyses the kinetic trajectory of abrasives both in initiative driving mode and passive driving mode, and the uniformity of lapping trajectory of the two opposite drive modes is discussed, respectively. The imperative relation between the kinematic trajectory and the uniformity is researched in this paper, as well as the simulation of the lapping trajectory.

Anisotropic Lapping of Single Crystal Sapphire

Lapping processes of single crystal sapphire are investigated in relation to crystallo- graphic orientation, the influence of the crystal anisotropism under different lapping liquid concentration, loading forces on materials removal rate and roughness in sapphire lapping is discussed. C-plane(0001),M-plane ( ),R-plane ( ),A-plane ( ) sapphire wafers were used for lapping experiments, experimental results show that Surface roughness is depend on the fracture toughness, surface orientation with higher fracture toughness such as C-plane would get better roughness during lapping, material removal rate of R-plane is the lowest in four planes, it is for elastic modulus and fracture toughness of R-plane are less than other three planes.