Applied Mechanics and Materials Vol. 493

Abstract: This research is about the system architecture for embedding of the Compact Fuzzy Logic Controller (Compact-FLC) into the FPGA with a minimal need in device resource. This exciting research is to minimize the FPGA resources needed to build Compact-FLC based on FPGA for controlling each joint of arm robots manipulator. Compact-FLC results of this research have been used in the XILINX Spartan 3 XC3S1000 FPGA.The Compact-FLC has been applied with satisfactory results as Servo Controller for one joint of arm robot manipulator which the results showed that the controller achieved a process speed of 65,4uS, which is equivalent to a maximum sampling frequency of 15.290 KHz. Output membership function in this Compact-FLC used singleton membership function with Center Of Area algorithm. Two input membership functions, i.e E (Error) and CE (Change Error) have been used, both formed from several combination of triangular membership functions. The maximum number of fuzzysets that can be processed is sixteen. The overlapping function is not limited because there have been 256 if-then rule available as look up table in FPGA's ROM.The device utilization summary from ISE of XILINX development software gave the following data: Slice FlipFlops needed are 3869 or 25% of 15360 availability, 4 input LUT needed are 2319 or 15% of 15360 availability, Blocks of RAM needed are 4 or 16% of 24 availability, MULT18x18s needed are 2 or 8% of 24 availability, GCLKs needed are 2 or 25% of 8 availability, Bonded IOBs needed are 32 or 18% of 173 availability.

Abstract: This paper discuss the organizational culture in metal manufacturing company which is classified as small and medium sized enterprises (SME) located in Central Java Province, Indonesia. This study is conducted to observe the action of the SME, especially for metal manufacturing company to face the regional free trade agreement in South-East Asia as a consequence of global market. The organizational culture is classified based on the internal factor, external factor, stability and control and flexibility and discretion. Four companies are involved in this study, where Company A, B and C are classified as small enterprises and Company D is classified as medium enterprise. The results described that the organizational culture is adhocracy for Company A, market for Company B and Company D and hierarchy for Company C. The adhocracy cultured company is predicted to be survived in ACFTA due to their innovative, customized and unique metal product and also specific customer. The medium enterprises is predicted to survive in ACFTA era due to their strong organizational structure, focused future plan, product diversification and measured product quality and standardization. The organizational culture for SMEs which is predicted to be suitable in winning ACFTA competition is adhocracy and market and supported by the product innovation, diversification and quality control. Mechanical and industrial engineers from university should takes place in assisting and supporting SMEs to win the competition in ACFTA era.

Abstract: Titanium and its alloys are hard materials, wear resistant, high strength to weight ratio. Therefore this material become very promising, especially in aerospace application. However, its application restrict when face machining processes. This material is very hard which is very difficult to manufacture by machining. Its low Youngs modulus tends to springy and creates vibration or chatter. Moreover, it has low heat dissipation rate that make the heat concentrate in the tool tip especially in the friction surface between tool and chip. Those phenomena result in very low tool life and low quality of machined surface, in term of surface roughness, surface integrity. This article describes some efforts to overcome those problems. Categorically, there are some groups of effort, i.e. varying machining parameters, modification the tool, treatment of the material, and different method of applying the coolant. It seems that using cryogenic cooling upon the tool is the most promising new technology to machine the titanium alloy.

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: The purpose of this study is illustrated the potential of applying the additive manufacturing (AM) technology with a low-cost three-dimensional (3D) printer on clinical applications of spine surgeries. First, the target vertebrae will be extracted from the computed tomography (CT) images of a patient and converted to a 3D polyhedral model. After choosing the target regions of pedicle screws in this 3D polyhedral model, the optimal screw angles and depths will be obtained without injuring the spinal cord. Then, a drill guide template of pedicle screws will be developed by using an AM software, and fabricated by a low-cost 3D printer. The doctor can utilize it to buckle the specific designed position of the vertebrae of the patient, and drill directly through the guide hole during the scoliosis surgery. These steps can reduce the surgical time substantially. Finally, several cases were executed to verify the placement accuracy of drill guide templates fabricated by the low-cost 3D printer.

Abstract: 2D (two-dimensional) motion is the basic motion for computer numerical controlled (CNC) machine in all industrial applications. In this paper, it is aimed to optimize the multi-performance characteristics, namely roundness error determined by best-fit-circle (REB), actual radius (R_act) and position time (Tt) that is the time needed for making a circular motion. By applying a Taguchi Grey Proportional Integral Derivative (TGPID) control method, the performance of this 2D multi linear motion is improved. The roundness error is closed to zero as time went to infinity which means the actual radius is closed to the reference radius. The position time differences (dTt) of X and Y axis for circling is also zero. This indicated the TGPID approach is robust.

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: 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: 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: 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.