Papers by Author: Bambang Pramujati

Abstract: This study described how the ironing process to manufacture 20 mm caliber bullet case. For this purpose, the first step is analyzing the process parameters, and then calculates the forces needed to make the formation of bullet case. Through the analysis of the process it is known, that the ironing process parameters most influential to the magnitude of forming force are the die angle α and the reduction of the wall thickness. In this study a simulation is conducted to determine a minimum required of forming force until the process successful. That means the required bullet case accordance with the determined specifications and geometry. The material used for bullet case caliber 20 mm is brass Cu30% Zn 70% early-shaped cup with 33.5 mm outer diameter, 3 mm thick and 37 mm high. Based on material strength calculation, the ironing force is determined with value of 50.01 kN. By using this value the maximum allowable wall reduction thickness in the ironing process is 26.7%. The simulation is carried out using finite element method on a variety of die angle such as α = 5°, 10°, 15°, 20° and 25° respectively. The simulation results show that the shell cannot through the die on each angle die. Similarly, in variation of reduction by 5%, 10%, 15%, 20% and 25%, the ironing process is also unsuccessful. However, by load of 138 kN, in the 26.7% reduction and at die angle α=5°, the ironing process to produce cylinder is successfully. Similarly by the same of wall thickness reduction, with force of 148 kN and the die angle of 10°, the ironing process is also successfully to fulfill the bullet case with a specified geometry.

Abstract: Robotics has lots of use in the industrial world and has lots of development since the industrial revolution, due to its qualities of high precision and accuracy. This paper is designed to display the qualities in a form of a writing robot. The aim of this study is to construct the system based on data gathered and to develop the control system based on the model. There are four aspects studied for this project, namely image processing, character recognition, image properties extraction and inverse kinematics. This paper served as discussion in modelling the robotic arm used for writing robot and generating theta for end effector position. Training data are generated through meshgrid, which is the fed through anfis.

Abstract: This paper presents the application of Taguchis method of orthogonal array and signal to noise ratio with logical fuzzy reasoning for multiple output optimization of turning AISI H13 steel using carbide tool. The cutting parameters, i.e., cutting speed, feed rate, depth of cut and nose radius, are optimized with considerations of multiple performance characteristics such as cutting force, feed force, surface roughness and tool flank wear. Experimental results are provided to illustrate the effectiveness of this approach.

Abstract: In the metal cutting industry, end milling has an important role in cutting metal to obtain the various required shapes and size. This study takes Al 6061 as working material and investigates three performance characteristics, i.e., tool wear (VB), surface roughness (Ra) and material removal rate (MRR), with Taguchi method and WPCA for determining the optimal parameters in the end milling process. The performance characteristic of MRR is larger-the-better while VB and Ra are having smaller-the-better performance characteristic. Based on Taguchi method, an L₁₈ mixed-orthogonal array was chosen for the experiments. The optimization was conducted by using weighted principal component analysis (WPCA). As a result, the optimization of complicated multiple performance characteristics was transformed into the optimization of single response performance index. The most significant machining parameters which affected the multiple performance characteristics were type of milling operation, spindle speed, feed rate and depth of cut. Experimental result have also shown that machining performance characteristics of end milling process can improved effectively through the combination of Taguchi method and WPCA.

Abstract: In this study, the optimization of recast layer thickness and surface roughness (SR) simultaneously in a Wire-EDM process by using Taguchi method with fuzzy logic has been applied. The Wire-EDM process parameters (arc on time, on time, open voltage, off time and servo voltage) were optimized with considerations of multiple performance characteristics, i.e., recast layer thickness and SR. Based on the Taguchi method, an L₁₈ mixed-orthogonal array table was chosen for the experiments. Fuzzy reasoning of the multiple performance characteristics has been developed based on fuzzy logic, which then converted into a fuzzy reasoning grade or FRG. As a result, the optimization of complicated multiple performance characteristics was transformed into the optimization of single response performance index. Experimental results have shown that machining performance characteristics of Wire-EDM process can be improved effectively through the combination of Taguchi method and fuzzy logic.

Abstract: This paper propose the optimization of the wire electrical discharge machining (WEDM) process of SKD61 tool steel (AISI H13). The use of the Taguchi method combined with grey relational analysis and fuzzy logic has been applied for optimization of multiple quality characteristics. The WEDM machining parameters (arc on time, on time, open voltage, off time and servo voltage) were optimized with considerations of multiple performance characteristics, i.e., MRR, SR and kerf. Arc on time was set at two different levels while the other four were set at three different levels. Based on Taguchi method, an L₁₈ mixed-orthogonal array was chosen for the experiments. Experimental results have shown that machining performance characteristics of WEDM process can be improved effectively through the combination of Taguchi method and grey-fuzzy logic.

Abstract: This paper proposes to understand about basic magnetic levitation model. Magnetic Levitation is repulsive or attractive force resulting gap from magnetic field. Characteristic of the magnetic levitation model is used permanent magnet and electromagnet with PID control to maintain wide gap between levitator and object levitation. Mass addition is used to analysis the model of the Maglev with PID control to maintain wide gap. Calculation result show that the maglev with PID control has sufficient levitation force in the maintain wide gap. Comparison between calculated and measured values can be done to build a another complex model magnetic levitation.

Abstract: Chatter is a self-excited vibration that occurs during machining process. It becomes a limitation to productivity and reduces the surface quality of work piece. Increasing dynamic stiffness of the work piece will improve its stability limit against chatter occurrence.Initial linear-approach simulation performing finite element modal and harmonic response analysis of the work piece filled with granular stiffener (sand and gravel) is presented. Drucker-Prager granular frictional material model is chosen to represent sand and gravel used as stiffener. Drucker-Prager parameters are chosen based on the experiment setting condition.Effect of an addition of the granular stiffener on the dynamic stiffness of the work piece will be evaluated. The simulation results are verified by experiment results.

Abstract: This paper presents the importance of simulation of metal flow in deep drawing process which employs an antilock brake mechanic system. Controlling the force and friction of the blank holder is imperative to assure that the sheet metal is not locked on the blank holder, and hence it flows smoothly into the die. The simulation was developed based on the material displacement, deformation and deep drawing force on flange in the radial direction, that it is controlled by blank holder with antilock brake mechanic system. The force to blank holder was applied periodically and the magnitude of force was kept constant during simulation process. In this study, the mechanical properties of the material were choses such that they equivalent to those of low carbon steel with its thickness of 0.2 mm. The diameter and the depth of the cylindrical cup-shaped product were 40 mm and 10 mm, respectively. The simulation results showed that the application of antilock brake mechanic system improves the ability to control the material flow during the drawing process, although the maximum blank holder force of 13000 N was applied. The optimum condition was found when the drawing process was performed using blank holder force of 3500 N, deep drawing force of 7000 N, friction coefficient of 0.25 and speed of punch stroke of 0.84 mm/sec. This research demonstrated that an antilock brake mechanic system can be implemented effectively to prevent cracking in deep drawing process.

Abstract: In this study, the optimization of material removal rate (MRR) and surface roughness (SR) simultaneously in a WEDM process by using Taguchi method with fuzzy logic has been applied. The Wire EDM process parameters (flushing pressure, on time, open voltage, off time and servo voltage) were optimized with considerations of multiple performance characteristics, i.e., MRR and SR. Based on the Taguchi method, an L₁₈ mixed-orthogonal array table was chosen for the experiments. Fuzzy reasoning of the multiple performance characteristics has been developed based on fuzzy logic, which then converted into a fuzzy reasoning grade or FRG. As a result, the optimization of complicated multiple performance characteristics was transformed into the optimization of single response performance index. Experimental results have shown that machining performance characteristics of Wire EDM process can be improved effectively through the combination of Taguchi method and fuzzy logic.