Advanced Materials Research Vol. 845

Abstract: This study investigates the effects of Friction Modifier Additives (FMA) added into the polishing slurry on Aluminium Nickel Phosphorous plated (Al-NiP) Hard-Disk Drive (HDD) substrates surface topography and surface defects during Chemical Mechanical Polishing (CMP) process. It is confirmed that addition of Friction Modifier Additives into the slurry reduces the overall coefficient of friction (CoF) during CMP process. By increasing the FMA concentration in the polishing slurry, the substrate surface topography such as waviness and surface roughness were improved significantly. It also lowered the defects counts especially scratch and sub-micron damage as revealed under Optical Surface Analyser (OSA) and Atomic Force Microscope (AFM) analysis.

Abstract: In this paper, the effect of the manufacturing process on free vibration modes of foam-core sandwich plate were experimentally identified from frequency response tests. Three types of foam-core sandwich plate that fabricated by using hand lay-up, vacuum bagging and vacuum infusion process were tested and compared. The responses were made at selected locations on the plate surface by attaching a single-axis accelerometer to measure out-of-plane response. Resonant frequencies, relative damping ratios and mode shapes were established for the lowest 3 out-of-plane modes found in the frequency range of 0-900 Hz. The results show that the vibration characteristics were affected by the fabrication process of the sandwich structure.

Abstract: Remanufacturing process among industries is relatively new in Malaysia. In USA, Europe, Japan, China and India, remanufacturing is already viewed as a huge business opportunity that significantly stimulates growth in Gross Domestic Product (GDP) and employment. The aim of this paper is to expose all possible causes of failures using the Ishikawa diagram and identify the most significant failures using Failure Mode and Effect Analysis (FMEA) with two Risk Priority Number (RPNs). The cleaning process is both time-consuming as well as the most costly of the entire remanufacturing processes. The case study is performed in an automotive contract remanufacturing environment in Malaysia, specifically the remanufacturing of cylinder heads. This work outcome explores the current situation pertaining to the cleaning process in a real world situation, and attempts to promote among researchers green ideas that will bring Malaysias remanufacturing on par with that of other developed countries.

Abstract: The chip forming process during end milling of glass fibre reinforced composites has been investigated in this study. The qualitative results from a high speed video camera has showed that discontinuous and fracturing of chips has been created due to the heterogeneity and insufficient ductility of the composite materials. The high-speed photography footage has also disclosed that a layer of delaminated chip can be formed as the tool cutting edge fractured the workpiece along the fibre orientation. The fracture of chips into smaller segments accelerated as the cutting speed increases. Likewise, shorter fragment of chips were created as the tool cut at different fibre orientation or angle. This makes it difficult to denote any chip formation processes during the end milling experiments.

Abstract: Additive Manufacturing is a promising field for making three dimensional scaffolds in which parts are fabricated directly from the 3D CAD model. This paper presents, the patients CT scan data of femur bone in DICOM format is exported into MIMICS software to stack 2D scan data into 3D model. Four layers of femur bone were selected for creation of customised femur bone scaffold. Unit cell designs such as double bend curve, S bend curve, U bend curve and steps were designed using SOLIDWORKS software. Basic primitives namely square, hexagon and octagon primitives of pore size 0.6mm, 0.7 mm and 0.8 mm diameter and inter distance 0.7mm, 0.8mm and 0.9 mm are used to design the scaffold structures. In 3matic software, patterns were developed by using the above four unit cells. Then, the four layers of bone and patterns were imported into 3matic to create customised bone scaffolds. The porosities of customised femur bone scaffold were determined using the MIMICS software. It was found that the customised femur bone scaffolds for the unit cell design of U bend curve with square primitives of pore size 0.8mm diameter and inter distance 0.7mm gives higher porosity of 56.58 % compared to other scaffolds. The models were then fabricated using 3D printing technique.

Abstract: Anterior Cruciatum Ligament (ACL) injury may cause other tissue injuries and degenerative joint diseases, rendering major surgery compulsory. The ACL substitutions from patients other tissue (autograft), from cadaver (allograft), or from other species (xenograft) still cause problems like donor morbidity, reduction of mechanical strength in cryopreservation period, and the risk of transgenic infection. Tissue engineering approach is the proposed solution. For this, synthetic ligament scaffold is needed. Electrospinning is a method to produce porous scaffolds made of polymers. In this study, filaments were produced from electrospinning poly l-lactic acid. The filaments were then twisted with 60o angle to the horizontal to make a yarn. Subsequently, the yarns were braided with the variation of braiding angle 40o, 60o and 80o. The characterization on the scaffold includes degradation rate, porosity, tensile strength, and cytotoxicity. It was found that larger braiding angle gave higher degradation rate, bigger pore size, and lower mechanical strength. For cytotoxicity, in terms of pore size and percentage of living cell, scaffold with braiding angle of 80o also showed the optimum result.

Abstract: The surface finishing resulting from metal cutting processes is associated with the surface texture and integrity. Texture can be quantified by roughness parameters as Roughness Average (R_a), Total Roughness (R_t), Maximum Surface Depth (R_y) and Surface Depth (R_z) which are directly related to cutting magnitudes and tool characteristics. This work assesses empirically the roughness generated by wiper cutting tools in dry finishing turning operations of AISI 4140 steel. By keeping a constant cutting speed and using depths of cut greater than 2/3 of the cutting tool radius (r_ε), four feed rates (f) are used with three r_ε, both combined in a way to ascertain the equations which allows the evaluation of R_a, R_t, R_y and R_z values. In order to determine the equations for roughness prediction a multiple linear regression method in function of f and r_ε is applied, showing good agreement with experimental results. Also, achieved results allows to prove the effectiveness of wiper tools to generate excellent surface finish without grinding operations and consequently showing that its use can increase significantly the material removal rate without compromising the surface roughness in high feed rate operations.

Abstract: Orthopaedic surgery procedure widely utilizes bone drilling in the work for correcting bone fracture and attaching prosthetics. Clean and accurately positioned holes are desired during bone drilling without damaging the surrounding tissues. However, bone temperature rises during drilling. It is always required to keep the temperature during drilling below 47 °C to avoid thermal osteonecrosis (bone cell death), which might lead to a loose of bone-implant interface. Drill design, drill parameters, and coolant delivery were believed to contribute to heat generation. As complex anisotropic biological tissues, determining the bone temperature during drilling is another issue. Complex mechanical and thermological properties are also other problems to be investigated due to the sensitivity to testing and specimen preparation.

Abstract: New feedstock formulation for metal injection moulding (MIM) of Molybdenum High Speed Steel (M2 HSS) has been developed. The binder is a multicomponent system consisting of major binder paraffin wax (PW), stearic acid (SA) and minor binder polyethelene waste rubber (PEWR). Injection moulding was conducted successfully using a powder loading of 0.65. Scanning electron micrograph of the green injection moulded part revealed homogenous distribution of the M2 HSS particles in the wax matrix. Paraffin wax and stearic acid were driven off by immersing the injection moulded part into n-heptane for five hours. Vacuum sintering of the brown parts at a temperature range of 1240°C-1280°C resulted in high quality M2 HSS parts. The properties of the sintered part such as physical, mechanical and microstructure were studied and discussed to evaluate the influence of waste rubber in MIM of M2 HSS.

Abstract: In this work, the electrode wear rate (EWR) and electrode surface characteristic of copper electrode when EDM of Nickel Based Super Alloy, Inconel 718 at higher peak current and pulse duration were analyzed. Experiments were conducted using Inconel 718 as a work piece and copper as an electrode with a kerosene dielectric under different peak currents and pulse durations. Peak current, I_p within a range of 20A to 40A and pulse duration (or pulse on-time), t_on within a range of 200μs to 400μs are selected as the main parameters. In this study, EWR were measured using digital weight balance (accuracy 0.01mg) and by using Scanning Electron Microscope (SEM), the surface texture of the electrode in order to evaluate the material deposited on the electrode surface. The results have shown that machining at a lowest peak current of 20A and highest pulse duration of 400μs yields the lowest electrode wear rate (EWR) of -0.01mm³/min. The pulse duration is significantly affecting the EWR. It also revealed that, the deposited of carbon and work piece material is occurred on the electrode surface for all machining conditions.