Mohammad Zulafif Rahim

Experimental study on quality of PCD tools machined by different electric discharge grinding processes

Abstract Polycrystalline diamond (PCD) is a promising tool material which is utilized to cut difficult-to-machine materials used in aerospace industry. Because of its ultra-hardness, electrical discharge grinding (EDG), a variation of electrical discharge machining, is often adopted to manufacture PCD tools to reduce manufacturing time. This paper investigates the quality of PCD inserts manufactured by two different EDG eroding methods: “2-step machining” and “3-step machining”. Surface roughness and residual stress were investigated after EDG process. An orthogonal cutting experiment was conducted to test the performance of each PCD insert. PCD tools machined with the two methods do not have significant difference in surface roughness. The residual stress status changed from compressive to tensile after EDG process. Also, after being eroded by 3-step EDG process, there was an over 30% declination of residual stress compared with 2-step machining. The results of the orthogonal cutting test showed that the wear amount and the thrust force of PCD inserts machined by 3-step EDG were smaller for the CTB010 insert and the CTX002 insert. In contrast, the CTM302 machined by 3-step EDG did not show obvious improvement in tool wear resistance during the cutting tests.

Laser Micro Welding of Dissimilar Material of Aluminum and Copper Alloys

Copper and aluminum are widely used in electronic industries for their excellence in electric and thermal conductivity. Joining these different material in scale of micro is hardly difficult for their obvious different in thermal properties. Melting these materials during welding process will create intermetallic compound which possesses new material properties. The melted zone became extremely brittle thus increase the possibility of failure due to cracks and concentrated loads. To overcome this problem, fundamental study is needed to characterize the material behavior against heat induction under various processing parameters. This study is an attempt to characterize the performance of Nd-YAG laser in micro joining of Al 1100 and Cu 101.

Ground proximity effect on the flow over NACA 4412 multi-element airfoil in clean configuration

The paper presents the influence of ground distance on aerodynamic characteristics of the flow over NACA 4412 multi-element airfoil in clean configuration. The angle of deflection was kept constant throughout the computations. Finite volume method was used for the grid generation and the numerical calculation. Further investigation suggests the best range of angle of attack where the aerodynamic performance of the airfoil increases in the presence of ground. Furthermore, the condition of flow separation jeopardizing the airfoil performance appeared. It was found that at certain range of angle of attack, the cushion of high pressure at the pressure side of the airfoil is insufficient to compensate the influence of the separation. This work shed insight on the important parameters that need to be taken into account in the operational of an airplane.

An Evaluation of Mechanical Properties on Kenaf Natural Fiber/Polyester Composite Structures as Table Tennis Blade

Nowadays, natural fibers getting attention from researchers and industries to optimize the use it, with combination of polymers as composite structure, due to environmental awareness. Furthermore, it show a few advantage, such as biodegradability, light in weight and non-toxic characteristic. In this study, kenaf natural fibers was used as reinforcement material, with combination of polyester as matrix material, known as polymer matrix composites. The main purpose of this study is to analysis the mechanical properties of kenaf natural fiber/polyester composite structure, in order to know the suitability of kenaf natural fibers as replacement material for table tennis blade structure, instead of using wood. The structural panel of composite laminates has been produced using hand lay-up technique. The experimental works are performed in tension, impact (Charpy) and shear condition. The characteristic of different condition on kenaf composite structure was studied. Based on the result, it found the properties of kenaf composite structure, and it will used as a benchmark, to compare with initial properties of table tennis blade made by wood. In addition, the strength and a weakness of that particular materials and lamination structure will be identified.

Small Horizontal Axis Wind Turbine under High Speed Operation: Study of Power Evaluation

Mechanical energy is produced through the rotation of wind turbine blades by air that convert the mechanical energy into electrical energy. Wind turbines are usually designed to be use for particular applications and design characteristics may vary depending on the area of use. The variety of applications is reflected on the size of turbines and their infrastructures, however, performance enhancement of wind turbine may start by analyzing the small horizontal axis wind turbine (SHAWT) under high wind speed operation. This paper analyzes the implementations of SHAWT turbines and investigates their performance in both simulation and real life. Depending on the real structure of the rotor geometry and aerodynamic test, the power performance of the SHAWT was simulated using ANSYS-FLUENT software at different wind speed up to 33.33 m/s (120km/h) in order to numerically investigate the actual turbine operation. Dynamic mesh and user define function (UDF) was used for revolving the rotor turbine via wind. Simulation results were further validated by experimental data and hence good matching was yielded. And for reducing the energy producing cost, car alternator was formed to be used as a small horizontal wind turbine. As a result, alternator-based turbine system was found to be a low-cost solution for exploitation of wind energy.

Designation of Soap Molder Machine and Procedure for Transparent Soap

Transparent soap is actually the combination of actual soap and solvent. The solvent is added into the soap solution to produce the transparent characteristic. The problem from the previous production is that tiny air bubbles were observed inside the soap resulted in less attractive appearance. Current method of producing the soap bar had taken more than 8 hours and having difficulties to take out the soap bar from the plastic mold with low production rate. It is expected that the air bubble problem can be solved using this new soup molder machine. The soap production rate is believed to increase with the invention of soap molder machine. By reducing the production time from 8 hours to 2 hours, it improve production rate significantly.

Investigation of carbon nanotube ink with PDMS printing plate on fine solid lines printed by micro-flexographic printing method

Micro-flexographic printing which is combination of flexography and micro-contact printing is a unique printing technique that create graphic, electronic and biomedical printed image on variable substrates. Therefore, an investigation for its potential usage in global area of printing hence a research for suitable ink and printing plate related to this process is vital. This paper will focus on investigating the printability of Carbon Nanotube (CNT) ink with polydimethylsiloxane (PDMS) printing plate. There are two types of CNTs ink which are solvent base and water base. A printing trial has been carried out in comparison with CNTs inks and PDMS printing plate with fine solid lines image on it to check the suitability of the printing plate development for micro-flexographic printing technique. The result shows that CNT water base ink is suitable with PDMS printing plate in printing fine solid lines image.

Solving Cracking Phenomenon in Premium Transparent Toilet Soap Production Using Stretched LLDPE Film Wrap

Cracking phenomenon in soap production is an imminent problem. It renders the soap aesthetically unpleasing. This study attempts to find best solution to solve cracking phenomenon in premium soap production. The adopted approach is a stamping method with stretched LLDPE wrap film. The result shows that stretched LLDPE wrap film able to solve the cracking problem. The appearance of the premium transparent was improved. This paper presents the results and the SOP for stretched LLDPE film wrap for soap making industries to adopt.

Residual Stress Analysis on Electrical Discharge Lapping (EDL) of Polycrystalline Diamond

PCD is the combination of diamond particles that are sintered together under high temperature and high pressure conditions in the presence of catalytic metal. Due to its superior properties, this material has been widely used for cutting tool. However, magnitude and direction of residual stress obtained from the fabrication process believe to affect the tool performance during application. Furthermore, high temperature generated by the process might also contribute to the structure alteration that finally reduces the strength of PCD. This paper revealed that the residual stress due to EDL is more dominant in tensile direction which is vice versa to the conventional process. Analysis on the spectrum indicated that there is a relationship between the tensile stress value and the composition of graphite on the Raman laser spot location.