Shamsuddin Sulaiman

Development of a CAD/CAM system for the closed-die forging process

Abstract The application of computer-aided engineering (CAE), computer-aided design (CAD), and computer-aided manufacturing (CAM), is essential in modern metal forming technology. Thus, the process of modelling for the investigation and understanding of deformation mechanics has become a major concern in recent and advanced research, and the finite element method (FEM) has assumed increased importance, particularly in the modelling of deformation processes. This work is devoted to the development of a CAD/CAM system for the closed-die forging process. The system development consists of three stages: namely, metal flow simulation, die failure analysis and design optimisation, and the development and implementation of a machining code. In the first stage, the FEM was used to simulate the axisymmetric closed-die forging process of copper material. The method is used to study the metal flow; die filling, retaining the non-linearity involved in the large change in the geometry; the continuous change in the contact surface condition; and the isotropic material work-hardening characteristics. In the second stage, a finite element analysis and optimisation algorithm is developed to examine the die fatigue life and to optimise the die design. The finite element analysis in the first and second stage was carried out using commercially available finite element software called LUSAS. In the third stage, a machining code for the optimised die is developed and implemented using CAD/CAM software called UniGraphics and CNC machine.

Finite element analysis on the effect of workpiece geometry on the quenching of ST50 steel

Abstract The finite element method (FEM) is employed to investigate the residual stress state and the variation of internal stresses in ST50 steel quenched from 600 to 0°C. Three different geometrical shapes of model were used, namely cylinder, cone and pyramid-shaped cone. Thermal analysis is first performed to obtain the cooling curves for the core and surface of the models, and this is followed by a full structural analysis. The results of the cylinder bar obtained from the computer simulation are compared with those experimentally determined values that are available in the literature and there appears to be a good measure of agreement. The study found that at the initial stages of the quenching process, the residual stresses were tensile at the surface and compressive in the core, however, towards the end of the quenching process, the tensile residual stresses switched to the core and compressive residual stresses at the surface. Under the same quenching conditions, if the models with different geometrical shape were tested, it has been found that the geometry has significant effect on the distribution and the magnitudes of the residual stress. Although the cylinder and the cone were different in shapes, but the residual stress state were not much in difference. Only when the cone turn into pyramid-shaped cone, the results were different and higher values of internal residual stress.

Flow analysis along the runner and gating system of a casting process

Abstract Simulation of molten metal flow along runner and gating system of pressure diecasting is carried out. Network analysis method is used for this simulation with the aid of a program written in FORTRAN language. This method is chosen to reduce the amount of computation needed. Analysis was done on runner and gating system with four gates. The angles of the branches leading to the gate and mould cavities are varied from 40° to 90°. This is to find out the pressure needed to be applied by the plunger of the injection system during the casting process and how branch angle of the runner and gating system affect it. Metal front movement will also be determined. The results of this study shows that smaller branch angle will require less pressure to fill the runner and gating system. The time required to fill the runner and gating system takes longer when smaller branch angle is used. Bend and large cross sectional area changes should be reduced as this leads to high pressure needed to be applied by the plunger. Larger time interval may be used without affecting the accuracy of the pressure calculated.

Experimental investigation for metal-filling system of pressure diecasting process on a cold chamber machine

Abstract This paper describes the molten metal flow in the filling system of pressure diecasting process. An experiment was carried out directly on a pressure diecasting machine (or cold chamber machine) to obtain the flow characteristics and pressure history. Three types of experiments were carried out on the machine, i.e. runs under normal pressure diecasting conditions, runs using a dry shot where no metal was injected, and tests using a short shot where piston plunger movement was stopped prior to complete fill of the cavity. Several shots were recorded and pressure time history and displacement time history under normal casting condition for the metal-injection phase were investigated and carried out successfully. The results are presented in a format, which enable convenient comparison with the predicted data.

Finite element analysis of filament-wound composite pressure vessel under internal pressure

In this study, finite element analysis (FEA) of composite overwrapped pressure vessel (COPV), using commercial software ABAQUS 6.12 was performed. The study deals with the simulation of aluminum pressure vessel overwrapping by Carbon/Epoxy fiber reinforced polymer (CFRP). Finite element method (FEM) was utilized to investigate the effects of winding angle on filament-wound pressure vessel. Burst pressure, maximum shell displacement and the optimum winding angle of the composite vessel under pure internal pressure were determined. The Laminae were oriented asymmetrically for [00,00]s, [150,-150]s, [300,-300]s, [450,-450]s, [550,-550]s, [600,-600]s, [750,-750]s, [900,-900]s orientations. An exact elastic solution along with the Tsai-Wu, Tsai-Hill and maximum stress failure criteria were employed for analyzing data. Investigations exposed that the optimum winding angle happens at 550 winding angle. Results were compared with the experimental ones and there was a good agreement between them.

Effect of equal channel angular extrusion on Al-6063 bending fatigue characteristics

The purpose of this investigation was to refine the grains of annealed 6063 aluminum alloy and to improve its yield stress and ultimate strength. This was accomplished via the equal channel angular extrusion (ECAE) process at a temperature of 200°C using route A, with a constant ram speed of 30 mm/min through a die angle of 90° between the die channels for as many as 6 passes. The experiments were conducted on an Avery universal testing machine. The results showed that the grain diameter decreased from 45 μm to 2.8 μm after 6 extrusion passes. The results also indicated that the major improvement in fatigue resistance occurred after the first pass. The subsequent passes improved the fatigue life but at a considerably lower rate. A maximum increase of 1100% in the case of low applied stresses and an approximately 2200% increase in fatigue resistance in the case of high applied stresses were observed after 5 passes. The improvement of fatigue resistance is presumed to be due to (1) a reduction in the size and the number of Si crystals with increasing number of ECAE passes, (2) the aggregation of Cu during the ECAE process, (3) the formation and growth of CuAl2 grains, and (4) grain refinement of the Al-6063 alloy during the ECAE process.

Design and development of an Integrated Slasher (Pulverizer) for Sweet Potato Harvester: A Review

In this study information on the development of combined sweet potato harvester is presented. The study focuses on the design, manufacture and choice of the best slasher for cutting and fragmentation of stems and leaves (vegetative portion) for the crop to facilitate the process of harvesting and extraction of tubers. A survey on various types and forms of cutters (mowers) and knives normally used for cutting vines and leaves was conducted and concluded that the vertical type and flail type mowers are the most effective in removing of the vegetative growth. In addition there is a need to design an integrated harvester, which combines both the cutting and digging in a single pass in order to reduce the time taken for harvesting, the fuel consumption and the number of machines used since this will give some economical advantages. In addition to the design requirements, it is recommended that number of tests should be conducted to select the suitable speed for the tractor, the velocity for cutters and the length of knives for both sides of the ridges to avoid damage to the tubers.

Improvements in the microstructure and fatigue behavior of pure copper using equal channel angular extrusion

In this study, annealed pure copper was extruded using equal channel angular extrusion (ECAE) for a maximum of eight passes. The fatigue resistance of extruded specimens was evaluated for different passes and applied stresses using fatigue tests, fractography, and metallography. The mechanical properties of the extruded material were obtained at a tensile test velocity of 0.5 mm/min. It was found that the maximum increase in strength occurred after the 2nd pass. The total increase in ultimate strength after eight passes was 94%. The results of fatigue tests indicated that a significant improvement in fatigue life occurred after the 2nd pass. In subsequent passes, the fatigue life continued to improve but at a considerably lower rate. The improved fatigue life was dependent on the number of passes and applied stresses. For low stresses (or high-cycle fatigue), a maximum increase in fatigue resistance of approximately 500% was observed for the extruded material after eight passes, whereas a maximum fatigue resistance of 5000% was obtained for high-applied stresses (or low-cycle fatigue). Optical microscopic examinations revealed grain refinements in the range of 32 to 4 μm. A maximum increase in impact energy absorption of 100% was achieved after eight passes. Consistent results were obtained from fractography and metallography examinations of the extruded material during fatigue tests.

Determining Optimum Electro Discharge Machining Parameters for Drilling of a Small Hole by Utilizing Taguchi Method

Electro discharge machining (EDM) is a process that uses an electric sparks to generate the high temperature and melt the workpiece. One of the EDM process is drilling. In EDM drilling, an electro thermal mechanism is introduced between the electrode and work piece to create the hole. The hole size is dependent on the diameters of electrode used during the drilling process. The present study performs Taguchi method to investigate the optimal process parameters for high-speed EDM super drill machine that is used to make a small hole. The workpiece used is made from titanium alloy (Ti-6: ASTM B348 Grade 5) and the copper electrode is 2.0 mm in diameter. In this experiment, the process parameters that were selected to be optimised are: current pulse off, maximum current and standard voltage levels. An orthogonal array L9 were employed to analyze the hole enlargement and material removal rate (MRR) depending on 2.0 mm diameter hole penetration. The optimum EDM parameters for hole making process was established and verified with the acquired results.

Recent developments of kenaf fibre reinforced thermoset composites: review

Abstract Kenaf fibres are recently upcoming reinforcement material to be used in composites. This is due to its low density, commercially viability, no health risk, high specific strength and modulus and renewability. It can also be cultivated in a variety of soil and is easily cultivable in some countries. Although traditionally it has been used for products such as rope, twine, bagging and rugs, recently, interests have grown for uses in other applications such as fibre reinforced composites. This paper reviews the recent developments in the use of kenaf fibre as a reinforcement material in thermoset composites. This paper also discusses the multiple types of kenaf fibres itself that are currently available in the market. The processes of kenaf cultivation and pretreatment have also been reviewed. The properties of various kenaf reinforced thermoset polymer composites, interface between kenaf fibre and matrix, and multitude of current manufacturing processes have also been discussed and presented. Recommendations for further research and development have also been given in this paper.