Advanced Materials Research Vol. 576

Abstract: All companies strive towards lowering their manufacturing costs. Few companies do however succeed in continuously improving their production after the launch of a new production process. This article introduces a method for companies having an established technology to optimize their production in terms of part cost without disrupting the normal, day-to-day production. By incrementally chancing the process parameters such as for example cutting data as a function of the originally selected values, it is possible to optimize the production process. This is closely related to the lean production philosophy and long term sustainability which strives towards efficient use of resources and involvement of all employees in improving the production process. In the case study presented in this article it was found that by adding extra sulfur to the cutting fluid it was possible to decrease the part cost. By using the proposed method the company was able to decrease the part cost when manufacturing a specific part with approximately 5 %.

Abstract: Boiler tube failures usually result in frequent forced outages, and ultimately in costly extended outages for major tubing replacement in a plant. There are several failure modes that may occur in a boiler tube, i.e. stress-corrosion cracking, pitting, water-side corrosion, fire-side corrosion, fatigue failure, overheating, dissimilar metal weld fatigue, mechanical fatigue and erosion. In this research the failure modes of boiler and its end cracks due to the dissimilar metal weld is analyzed. Hence data are collected and explored to determine the cause of failure and as a solution ceramic ferrule is suggested. The use of ceramic ferrule in boiler tube can eliminate the crack occurrence or delay the process due to thermal properties. The prevention of crack will reduce frequent maintenance and thus the cost of operation can be minimized.

Abstract: Free Space Optics (FSO) communication is a technology widely used today. It involves transmission of data from a transmitter to a receiver. In order to achieve successful data transmission, a continuous alignment between the transmitter and receiver telescope is needed. If not, misalignment will happen due to certain factors. Vibration at the transmitter or the receiver is one of the factors that contribute to misalignment. In this work, active vibration isolation (AVI) system is designed and fabricated in order to improve the performance of the transmitter and receiver in an FSO link. First, a virtual prototype is designed. Then a real prototype is fabricated to implement AVI. The result after applying a controller to the AVI system shows 33.1% reduction in amplitude of displacement of the top plate, in other words reduction in amplitude of vibration.

Abstract: Towards green material, fatigue life of unidirectional kenaf fibre reinforced epoxy composites was investigated made from the hand-layout technique. The composites were subjected to tension-tension fatigue loading at stress ratio of 0.5 and 5 Hz of frequency. Fibre content ratios were found to affect fatigue life on the low cycle fatigue regime strongly as illustrated with stress level versus cycles to failure. It is found that kenaf fibre reinforced epoxy composites with higher fibre content posses higher load carrying capacity and degradation rates.

Abstract: Tensile strength of Aluminum A6061 joint produced by spinning friction welding (SFW) with various chamfer angles was studied. Tensile strength test specimens that have weld joint part at their centers were machined from spinning friction welded base metals. SFW specimens were prepared by making various chamfer angles of 15, 30, 45, 60, 75 degree and without chamfer angle on both contact-surfaces of base materials. It was found that chamfer angle affected tensile strength of weld joint of Aluminum A6061. Base materials with chamfer angle of 30 degree resulted in specimen that had the maximum tensile strength of friction weld joint. From the result of macrostructure evaluation, it was found that high strength in these specimens was due to the maximum area of fully plasticized zone, minimum porosity and minimum area of heat-affected zone.

Abstract: The thermo elastic edge-cracking problem in bimaterial systems subjected to convective heating is considered. The medium is assumed to be insulated on one surface and exposed to sudden convective heating on another surface containing the edge crack. Superposition and uncoupled quasi-static thermoelasticity principles are adopted to formulate the problem. Thermal stress distribution and stress intensity factor values had been determined using the finite element software ANSYS for two different bi-material systems containing edge crack normal to the interface.

Abstract: This paper investigates the performance of organic solar cells by using different types of metal contact. The metal contacts that have been chosen are Ag, Au and Pt. The different work function of the metals will influence the efficiency of the organic solar cells. From the results it can be seen that the absorbance value is quite high around 0.5 which absorb more photon when it is illuminated. The efficiency of the device using Pt shows the highest efficiency which is 10.62x10-3% followed by Au with 8.01x10-4% and Ag 1.25x10-4%.

Abstract: Free-space optics (FSO) communication is a technology that uses light to transmit data through free space. The most important part in FSO communication is the alignment between transmitter and telescope’s receiver. However, since the transmission medium of FSO is atmosphere, it will give misalignment between the transceivers. Hence, auto tracking system is required to solve the problem between the transmitter and receivers. The 3-RPS parallel manipulator has been designed as an auto tracking system for the alignment between transceivers. First, a prototype of the system is designed in SolidWorks and integrated with LabVIEW software to perform virtual prototyping. Then, the result of virtual prrotyping is discussed.

Abstract: HLV 30 Piercing Machine produced by SMG Pressen, an engineering company from Germany that exercising the task of piercing of LPG cylinder for valving process. This particular machine is used by LPG cylinder production plant, and one of them is Keloil LPG Cylinders Sdn. Bhd. This research project intend to study how this piercing process affects the production quality of the LPG gas and also to develop and design the new jig and fixture for this machine to get the accurate tolerance for the piercing process and decrease the index of rejection of the cylinder. In this research, we try to analyze the production data and try to make a new design of fixtures for this machine to get the better result and performance for this machine.

Abstract: Nitrogen doped amorphous carbon (n-C:N) solar cells were successfully prepared using a simple and low cost Chemical Vapor Deposition (CVD) method using camphor oil as a precursor. Four samples of n-C:N were deposited by varying the deposition temperature (500oC, 550oC, 600oC, 650oC). The fabricated solar cell using n-C:N with the configuration of Au/n-C:N/p-Si/Au achieved an increasing efficiency as temperature increase (0.000202% to 0.001089%). As a reference, pure a-C was deposited at 500oC and exhibit 0.000048% efficiency. The current-voltage (I-V) graph emphasized on the linear graph (ohmic) for the a-C thin films, whereas for the p-n device structure, a rectifying curve was obtained. Electrical conductitivity possesses increasing value (1.69 x 10-2 to 22 Ω-1 cm-1) due to increasing sp2 ratio in a-C as temperature increase. The rectifying curves signify the heterojunction between the n-doped a-C film and the p-Si substrate and designate the generation of electron-hole pair of the samples under illumination. Photoresponse characteristics of the deposited a-C was highlighted when being illuminated (AM 1.5 illumination: 100 mW/cm2, 25oC) and optical band gap for the nitrogen doped a-C is reported from 0.75 eV to 0.25 eV as temperature increase.