Advanced Materials Research Vols. 24-25

Abstract: Top-quality surfaces are obtained by means of pulse electrochemical finishing (PECF) in neutral electrolyte. The machining principles and advantages of PECF are analyzed. Moreover, the technique are applied to some typical cases such as sheeny lettering, fine and deep holes and complex shaped surface finishing, gear surface finishing that all of them are more difficult to be machined by the traditional finishing technologies. The results show mirror-like surfaces could be gained by PECF and the surface roughness values could be reduced from more than Ra 0.8 μm to less than Ra 0.08 μm within 1~2 seconds. It’s hoped that PECF will play an important role in finishing key parts in the modern manufacturing industries.

Abstract: The influence of whisker orientation on machining mechanism, material removal rate and roughness of finished surface when machining the hydroxyapatite /SiCw composite bioceramics material using ultrasonic machining technology was studied. The research results show that material removal rate and roughness of finished surface increase with the increase of the direction angle θ . Under the same machining condition, the higher is the fracture toughness of the material, the lower the material removal rate is. This provides basis for the ultrasonic machining of hydroxyapatite /SiCw composite bioceramics material.

Abstract: High density and isotropic poreless structure of Glass-like-carbon makes it practically used for fuel cells of space-shuttles and hard disk substrate etc. Glass-like-carbon is one of the new materials which attract attention, but it is so hard and brittle that precise machining of this material is difficult. Surface grinding and slicing were performed to collect the fundamental data of precise machining. The main results obtained in this study are as follows. (1) The transition from brittle mode to ductile mode in surface grinding occurs at a grain mesh size between #5000 and #3000. (2) The maximum grain depth of cut ‘dg’ necessary for ductile mode grinding is 0.021-0.006 mm or less. (3) When it is being sliced, the kerf width of the #1000 grinding wheel becomes wider than that of the #2000 grinding wheel because of the fact that the material removal capability of the #1000 grinding wheel is bigger than that of the #2000 grinding wheel. (4) It is extremely effective to use the fine grinding wheel, since the Young's modulus of glass-like-carbon is considerably low and eventually causes compression transformation,.

Abstract: 2D finite element model with the same material for backup to minimize the burr size was developed to investigate mechanism of burr formation and burr minimization. The flowstress of the workpiece and backup material are taken as a function of strain, strain-rate and temperature. Temperature-dependent material properties are also considered. The Cockroft-Latham damage criterion has been adopted to simulate ductile fracture. The crack initiation and propagation is simulated by deleting the mesh element. The result shows putting a backup material behind the edge of the workpiece is an effective way to minimize the burr size. The effects of cutting condition, temperature and different backup material properties on the burr formation and burr size can be investigated using the developed finite element model. This model could be useful in the search for optimal tool geometry and cutting condition for burr minimization and for the modeling of a burr formation mechanism.

Abstract: This paper focuses on the application of Taguchi method for optimization of SUS440 stainless steel polishing process parameters to obtain the best finish. An optimization experiment for polishing stainless steel with SiO2 was designed by Taguchi method. Surface roughness Ra is considered as criteria for optimization. Influence of parameters involving load, speed, and slurry concentration for a given workmaterial with given abrasive (material and size) are discussed, and the optimum polishing conditions are figured out. Compared with single parameter experimental results, it illustrates that the experiment design based on Taguchi method can successfully applied to determine the optimum processing conditions for SUS440 stainless steel polishing process.

Abstract: BEST-JAPAN has being proceeded the standardization of the Edge Quality. Already, we announced this one at international conference on “Precision Surface Finishing and Deburring” at San Francisco and St. Petersburg. This paper describes the discussion of the Edge Quality and Indication & Evaluation Methods of The Edge Quality.

Abstract: This paper studies on a newly developed method, WEDM in gas, and discribes the features of finishing dry-WEDMed surface, such as narrower discharge gap length, higher surface straightness accuracy and no electrochemical etching actions. Low-speed WEDM removal rate in gas can be improved by increasing the wire winding speed. High-speed WEDM in gas has a significant advantage as high removal rate beyond the abovementioned good points, which is available for improving conventional high-speed WEDM quality.

Abstract: There are lower grinding force and temperature in quick-point grinding process because of the higher grinding speed and the less depth of cut, especially the point contact between the grinding wheel and the workpiece due to the point grinding angles. Thus it can achieve better surface finishing process in grinding cylindrical surface. Since the point grinding model is different from the conventional cylindrical grinding in theory, the surface roughness is in relation to the point-grinding angles greatly besides the grain granularity, depth of cut, grinding speed and axial feeding rate like the conventional cylindrical grinding process. Based on the theoretical studies on the surface roughness in the process, the surface finishing experiments and measures at the various grinding parameters were performed. The experimental results show that the process parameters, such as point-grinding angles, depth of cut, grinding speed and axial feeding rate, must be controlled reasonably for the higher surface finishing demand in quick-point grinding process.

Abstract: In this paper, based on analyzing the properties of medical Ti-6Al-4V Titanium alloy, the author takes the purpose of studying the machinability of the medical Ti-6Al-4V Titanium alloy and aims at improving the tool durability. The study starts from the tool material, geometrical parameters of the tools, usage for the cutting and other aspects in order to achieve the suitability of selecting cutting tool as well as the optimization of choosing cutting usage which lays the foundation for further investigation of the machinability of the medical Ti-6Al-4V Titanium alloy and carry out the online optimization of cutting parameters.

Abstract: Electrochemical buffing technology (ECB) applies electrochemical and mechanical finishing characteristics in the surface finishing process. ECB can buff ultrahigh purity components to make them shine, without leaving residual stress, micro-cracks, and etc. The control parameters of the ECB process include current density, the rate of revolution of the buffing head, the buffing pressure on the surface, the concentration of electrolyte, the buffing time and others. Improper control parameter setting in the process will result in unsatisfactory surface quality. It is necessary to determine optimal control parameters of an ECB process with robust performance that can insure surface quality and process reliability. In this study, parametric analyses were conducted on electrochemical buffing technology.An ECB system with a CNC machine was established. The buffing head was clamped on the tool holder of the CNC machine. It was used on a flat surface for automatic surface buffing. Taguchi′s parameter design approach is employed to evaluate signal-to-noise ratios (SN) given from various levels of these factors. Then, the optimized control parameters will be recognized thus can get the optimal surface buffing, reducing with the lowest variability. The contribution of every factor to the sum of square is calculated. An experiment is performed using the optimal control parameters to confirm the results of the previous experiment. The results reveal that the ECB process yields the desired mirror-like surface.