Jiang Wen Liu

Single Pulse Study of Electrochemical Discharge Machining of Metal Matrix Composites

Single pulse experiments were conducted to study electrochemical discharge machining (ECDM) of particulate reinforced metal matrix composites (MMCs) which are widely used in the packaging industry. This article reports the first phase of this study with an emphasis on the effects of pulse current on crater volume. The results showed that all the ECDM craters have a circular shape surrounded by a rim of re-solidified material. This indicates that ECDM craters were created by arc effect. The craters produced by both electrical discharge machining (EDM) and ECDM increased in volume with increasing peak current. However, within the range of currents studied, the craters formed by ECDM were always smaller than those produced by EDM alone under the same current. Moreover, the crater volume difference between EDM and ECDM did not change considerably with increasing current. This is considered to be due to an increase in ECDM current mainly enhances the arc energy and has little effect on the ECM action. Furthermore, the experiment results showed that the efficiency of the arc action in ECDM is reduced when the percent of reinforcement phase is increased.

An Orthogonal Experimental Analysis of WEDM-HS of Al2O3 Particle-Reinforced Aluminum Alloy 6061 with 10-Vol% Al2O3

In wire electro-discharge machining with an extremely high travelling speed of wire electrode (WEDM-HS), the emulsion is used as working liquid. Because there exists a functional electrolyte, the EDM spark can operate under a relatively large spark gap size condition, and this would facilitate the removal of machined debris. An investigation has been made into the machining feasibility when WEDM-HS has been employed to process Al2O3 particle reinforced aluminum alloy 6061 with 10-vol% Al2O3 (10ALO). And the material removal rate (MRR) has been examined in this study. Since there are many factors that can influence the MRR in the WEDM-HS process, in order to determine which is the most important factor and to optimize the machining parameters, the relative importance of the various machining parameters on material removal rate was established by utilizing an orthogonal experimental analysis. The results of the analysis suggest that to achieve a high MRR for particulate reinforced aluminum 6061 with 10-vol% Al2O3, the duty cycle is the most influential factor among current, pulse duration and duty cycle. And the impact of the different factors follows the sequence of duty cycle > current > pulse duration.

Single pulse studies of the electrical discharge machining of metal matrix composite materials

Abstract The main objective of this investigation is to study the influence of the processing medium and gap distance on the electrical discharge machining process performance while machining metal matrix composite materials. Machining characteristic of electrical discharge machining in air and emulsified oil medium has been compared. The effects of medium, gap distance on the crater size have been studied. The study shows that the discharge modes in both of the medium are all in the form of an arc. And it was also found that the material removal rate of EDM in emulsified oil was considerable higher (about 300%) than that in air medium under the experimental conditions of this study. Moreover, in both air and emulsified oil medium, more molten materials can be flushed out if the gap distance has been enlarged.

Automobile crashworthiness improvement by energy-absorbing characterisation of aluminium foam porosity

Abstract Aluminium foam has been adopted as one of the light filler materials in auto body structural components because of its excellent energy-absorbing ability and lightweight which play a key role in reducing weight and improving safety. This paper combines the porosity of aluminium foam material and the application in cars crashworthy structures to present the energy-absorption behavior and its effect evaluation. First, the paper focuses on the effect of porosity on the energy absorption by experimental study. All the experiments were performed with the specimens subjected to quasi-static axial loadings. As the experimental results, the energy-absorbing properties on porosity are presented, implying that the porosity is a very sensitive factor to energy absorption and the best porosity of aluminium foam in energy-absorption capacity was obtained. A case study on aluminium foam-filled material for automobile front rails was carried out by collision simulations, the improved crashworthiness was verified.

Study on an Aliphatic Polyurethane Laminating Adhesive Based on Castor Oil

The first component of the Polyurethane adhesive was prepared with polyester polyol, polyether polyol ,castor oil and isophorone diisocyanate. And this component was mixed with the castor oil and its modified production to prepare a two-component solvent-free aliphatic polyurethane laminating adhesive. In this study, the influences of the copolymerization ratio of polyester/ether on viscosity, heat resistance, adhesion strength and boiling resistance were studied, as well as influences of castor oil and its modified production on curing speed and adhesion strength. The results showed that when proportion of polyether diol was 25% and castor oil was 50% of the total hydroxyl content of first component, the PU adhesive with lower viscosity, better reactivity and enhanced boiling resistance would be achieved. And with an appropriate amount of derivatives castor oil in second component, the curing speed and adhesion strength of the PU adhesive were significantly improved.

A numerical model and computer simulation for machining particle reinforced metal matrix composites in electric discharge machining

Abstract A numerical model has been proposed to predict the material removal of electric discharge machining process while it is machining a particulate reinforced aluminium 6061 with 10 vol.-% Al2O3. The heating effect of an electric discharge machining spark on the temperature field of the workpiece was analysed using ANSYS software. According to the simulated temperature field profiles, the diameter, depth and volume of the crater created by a single electric discharge machining pulse can all be obtained. The influence of pulse duration and discharge current on the material removal mechanism was theoretically and experimentally investigated. It was found that the experimental results agreed well with the simulated results. The average percentage errors of the crater volume were found to be 3·2% at different discharge current conditions, and 2·5% at different pulse duration conditions.

A Regression-Based Cycle Time Estimator for the PCB Placement Machine

The assembly of printed circuit boards is conducted by the sophisticated PCB placement machines. The cycle time for a machine to complete an assembly job is determined by solving two machine optimization problems, i.e., the feeder arrangement and placement sequencing.Rapid and accurate estimation of these cycle times is important for solving the higher level planning problems including the line balancing problem. In this paper, a regression-based estimator was established to estimate the cycle time. Statistical results on 100 PCB samples showed that the proposed estimator could estimate the cycle times accurately. At the same time, the computationally efficiency makes it suitableto be used in solving higher level planning problems.

An Orthogonal Experimental Study of WEDM-HS of Particle-Reinforced 6061 Al Matrix Composites with 20-Vol% Al2O3

An investigation has been made into the machining feasibility when wire electro-discharge machining with an extremely high travelling speed of wire electrode (WEDM-HS) has been employed to process particle-reinforced 6061 Al matrix composites with 20-vol% Al2O3 (20ALO). And in this study, for the water based emulsion is used as working liquid, there exists an electrochemical effect. And thus, the EDM spark can operate under a relatively large spark gap size condition, and this would be helpful for the removal of the loosen particles and the machined debris. In this study, the material removal rate (MRR) has been examined. Since there are many factors that can influence the MRR during the wire electro-discharge machining process, in order to determine which factor has the most significant effect on the MRR and to obtain the optimal machining parameters, the relative importance of the various machining parameters on material removal rate was analysed by employing an orthogonal design. The results of the orthogonal analysis show that to obtain a high MRR for WEDM-HS machining of 20ALO materials, the duty cycle has the most significant effect on the MRR among current, pulse duration and duty cycle. And the impact of significance for the different factors follows the sequence of duty cycle > current > pulse duration. And under the experiment condition of this study, a duty cycle of 1:4, a current of 5A and a pulse duration of 32μs is the best arrangement for the MRR.

Data Dissemination and Visualization Browsing of Digital Map Based on Web

We proposed overall design of the visualization browsing map data in network environment in this paper. And we developed map data flow according to the data structure and attributes of map data base. We programmed one map display control, MapCtrl.ocx, with GUI in the specific implementation. It could browse the map by utilizing map data base and self-designed map symbol base. Furthermore, we detailed the specific process of programming the control and the related techniques, such as component technique, data exchange technique and display technique. We developed a prototype of map data visualization browsing system based on ActiveX in network environment, which could achieve several functions such as browsing vector graphics of map data on internet, operation and simple query and analysis.

Halftoning Method and Reproduction of Color Gamut in Digital Image Output

Image halftoning is the core technique of digital image output, which determines the quality of the color and tonal gradation reproduction. In this paper, the existing halftoning techniques were analyzed and evaluated, such as FM halftoning and AM halftoning, etc. And a new halftoning mode, frequency conversion amplitude modulation (FCAM), was proposed. This method is still based on AM halftoning, but it uses the different screen frequency for halftoning image of the different color version, so as to avoid moiré fringes on the smaller superposition angle. The use of new halftoning model can achieve halftoning image output which is more than 4 colors (such as 6 colors or 7 colors) without visual moirè pattern when overprinting. By the new technique, high-fidelity printing is achieved, and the color gamut of the output image is expanded, and we can get more vivid realistic effect of image transmission. We tested color gamut expansion of 6 colors and 7 colors high-fidelity printing, and obtained the expected conclusion by quantitative analysis.