Materials Science Forum Vols. 505-507

Abstract: There are several types of welding method to join metal and ceramic. This paper gives a description of an experimental study of the ultrasonic welding of aluminum wire and silicon wafer under the conditions of the frequency of ultrasonic vibration f = 38000Hz, the applied duration T=0.2-1.5 sec, and the welding force Ps =40-140 gf. In this study, vacuum deposition was first applied to deposit surface modification aluminum on silicon wafer, then ultrasonic welding processes were investigated to join aluminum wire and modified silicon wafer. Based on the results of the microstructure observation and tensile test, it is believed that the joining ability can be improved under optimum welding condition.

Abstract: An experimental analysis is presented which investigates the relationship between cutting parameters and the volume of material removal as well as its cutting quality on a Nd:YAG laser cutting system. The parameters that varied on two testing thickness during cutting include cutting speed, incident laser power and focal position in a continuous through cut. Various trends of the kerf geometrical features in terms of the varying process parameters are analyzed and shown to be reasonable. Discussions are also given on kerf geometry control in situations with cutting parameters. It shows that the effects of varying parameters such as cutting speed, laser power and focal position on cutting kerf width, surface roughness, and striation that have provided a deeper understanding of the laser machining.

Abstract: The main object of the present work was to develop an ultrasonic aided electrical discharge grinding (UAEDG) methodology to remove the re-solidified layer through the grinding induced by a metal matrix composite electrode prior to the re-solidification of molten material. A metal matrix composite (Cu/SiCp) electrode, with an electroless pretreatment of Cu coating on SiCp to enhance bonding status between Cu and SiCp, was employed to study the UAEDG technology. The machinability of the mold steel SKD11 was investigated by the combined technologies of UAEDG. The machined surfaces of these materials were examined by optical microscopy（OM）and their surface roughness measured by a profilemeter.

Abstract: Spindle speed variation (SSV) is one of a number of promising strategies to suppress chatter. Most previous research on SSV stability analysis for nonintermittent machining processes has focused on stationary-bar boring or turning. However, nonintermittent rotating-tool machining is also a common process. This paper investigates the effect of SSV in nonintermittent rotating-tool machining, using rotating-bar boring as an example. This paper takes advantage of the rotating-frame approach and the resulting constant delay in the angle domain to investigate the SSV effect on system stability for rotating-bar boring. The results show that the SSV effect on rotating-bar boring flattens the stability lobes and lifts the tangential stability limits.

Abstract: The pulse DC plasma system offers so highly instant power to generate extremely intense plasma density that its applications are widely extended. In this work, the development of pulse DC plasma processing is studied for the sheet resistors, and the manufacturing mechanism relative to the properties of copper particles deposited on plastic materials is discussed by using atomic force microscopy and line-resistance measured technique.

Abstract: This paper investigates the characteristics of a hydro-mechanical punching process. The hydro-mechanical punching process is divided into two stages: the first stage is the mechanical half piercing in which an upper punch goes down before the initial crack is occurred; the second stage is the hydro punching in which a lower punch goes up until the final fracture is occurred. Ductile fracture criteria such as the Cockcroft et al., Brozzo et al. and Oyane et al. are adopted to predict the fracture of a sheet material. The index value of ductile fracture criteria is calculated with a user material subroutine, VUMAT in the ABAQUS
Explicit. The hydrostatic pressure retards the initiation of a crack in the upper region of the blank and induces another crack in the lower region of the blank during the punching process. The final fracture zone is placed at the middle surface of the blank to the thickness direction. The result demonstrates that the hydro-mechanical punching process makes a finer shearing surface than the conventional one as hydrostatic pressure increases.

Abstract: CNC machining is one of the most widely used manufacturing processes. While possessing good flexibility and fast cycle time, there are some restrictions imposed depending on the geometry of the part to be machined. One challenge often encountered is the machining of thinwall structures. The instability and deflection of the thin-wall causes difficulty for control of the machining condition, affecting the accuracy of the modeling and simulation of the process. This paper presents an alternative machining method called spiral-layer machining that could improve this condition using the concept of layer manufacturing technology and technologies that would reduce the machining force or tool-force variation and divert the force-vector. A case study of machining a turbine blade was conducted to verify the method. The result was successful in terms of stability and feasibility. Error correction techniques are being investigated to ensure good dimensional precision of the part.

Abstract: Using survey data, this research identified the relationship between technology orientation (manufacturing flexibility and advance manufacturing technology), and customer orientation (customer focus and customer satisfaction) to development of manufacturing strategy. This framework is then tested on a sample of 52 firms in plastics injection industry, Taipei County, Taiwan. The results show significant relationships in the framework with four models. They support the argument found in the literatures that manufacturing strategy builds should related to technological development and market place. Implications of the findings are discussed.

Abstract: The knowledge obtained from the experience of monitoring manufacturing process is critical to guarantee good products produced at the end of manufacturing line. Recently, many methods have been developed for the described purpose above. In this paper, a new knowledge discovery model based on soft computing is proposed. The proposed model contains a new algorithm Modified Correlation-based Feature Selection (MCFS), a new algorithm Modified Minimum Entropy Principle Algorithm (MMEPA), and Variable Precision Rough Set Model (VP-model). After conducting a real case of monitoring the process of manufacturing industrial conveyor belt, some advantages of the proposed model are that (1) MCFS can quickly identifying and screening irrelevant, redundant, and noisy features for data reduction; (2) MMEPA can objectively construct membership functions of fuzzy sets for fuzzifing the reduced dataset; (3) VP-model can extract causal relationship rules for controlling product quality; (4) Extracted rules by the proposed knowledge discovery model are easily understood and interpretable.

Abstract: This paper presents a methodology for obtaining an optimal parting line of an injection mould based on FEM analysis and managements. This research utilizes Taguchi’s method to design a DATABASE for the gate position and warping of parts. Firstly, it sets up an injection model via a CAD system, and secondly, utilizes FEM to analyze the warp of the injection mould in different gate positions. Because of different gate positions, the parts experienced extreme differences in the amount of warping. This paper applies the neural network (abductive network) to build the relationship (database) between the gate position and amount of warp. Engineers can use this database without recourse to a CAD model and FEM solution to predict the amount of warping at different gate positions. This procedure saves time in building CAD models and on carrying out FEM analysis. The optimal parting line parameters can then be reached through a Simulated Annealing (SA) optimization algorithm. The methodology uses multi-objective function criteria, with a performance index to obtain perfect parts. This method of database management can offer various design fields of injection mould (e.g., design of gating and runner, and design of cooling system). It already achieves real optimization of design for injection moulding.