Applied Mechanics and Materials Vols. 789-790

Abstract: The aim of this study is to optimize the process variables of a novel hybrid process of electrical discharge machining (EDM) and abrasive jet machining (AJM) using grey relational analysis. The multi-performance characteristics associated with the developed hybrid process such as the material removal rate (MRR), electrode wear rate (EWR), and surface roughness (SR) were explored through an experimental study according to an L18 orthogonal array based on the Taguchi experimental design method. The experimental results confirmed the multi-performance characteristics of the developed hybrid process would clearly be improved through optimizing the process variables using grey relational analysis.

Abstract: Trimming process using Solid Carbide, 4 flute endmill of 8mm diameter tool on stacks of multidirectional CFRP/Al-2024 in a CNC Milling machine was experimentally investigated. The machining parameters considered were spindle speed (N), feed rate (f_r) and depth of cut (d_c). The aims were to analyze the influence factors and the interaction of these parameters with respect to surface quality produced. A Two Level Factorial Design method was used to plan systematic experiments. The influence factors and the interaction between these parameters are analyzed and the optimum machining parameters for minimizing the surface roughness is determined. The analysis of variance (ANOVA) shows that d_c and f_r are the most significant parameters to the overall performance of surface quality. Surface roughness of CFRP is found to be 1.778 µm and Al2024 is found to be 0.983 µm at the setting of N = 1860 rpm, f_r = 620 mm/min and d_c = 0.12 mm respectively. The validation test shows deviation of predicted to actual value surface roughness is 7.87% for CFRP and 6.61 % for Al2024.

Abstract: This paper is to study the application of Taguchi Method when experimental cutting on Copper (CuA1) generated by a milling machine. The respone of this study is surface roughness while machining with varying machining parameters such as cutting speed, feed rate and depth of cut. This experiment is using end mill HSS Ø16mm with uncoated and 2 flute with sequences of experiment base on the Taguchi Orthogonal array L₉3⁴ which carry out with 9 of experiments. The signal-to-noise (S/N) ratio, the analysis of variance (ANOVA) and confirmation tests with the optimal levels of machining parameters are carried out in order to illustrate the effectiveness of the Taguchi optimization method.

Abstract: This study, based on finite element analysis, analyzed the spring back phenomenon and stress distribution of forming sheets (HTS) in the roll forming process. By comparison of the stress distribution, this study analyzed two kinds of simulation. The first simulation performed simple bending simulation before roll forming simulation. With reference to the first simulation results, the second simulation analyzed the relationship between the stress distribution and the phenomenon of spring back. We also studied the stress distribution effect for spring back in the forming sheet.

Abstract: The hard spots are investigated in ADC12 die casting cylinder blocks for air compressors using metallographic method and a micro- hardness tester. The results show that the hard spots have two main shapes. There is a nonuniform micro-hardness distribution within a hard spot. Energy dispersive spectrometry (EDS) analysis reveals that these hard spots are some kind of mixture of oxide and carbide, which are formed during melting and die casting process.

Abstract: One of the challenges which Laser Sintering faces is the Rapid Manufacturing of plastic parts with good consistent quality. This is due to the fact that plastic powder properties deteriorate during the long periods of time through the LS building and cooling cycles. This paper presents an experimental study of the deterioration or ageing of PA12 powder properties in the LS process. The influences of different grades of recycled PA12 powders are investigated. The main aim of this research is to develop a methodology of controlling the input material properties that will ensure consistent and good quality of the fabricated parts. From the experiment it was found that PA12 powder with high melt flow rate, low melting temperature, low glass transition temperature and low degree of crystallization temperature could improve the sintering process to produce a good Laser Sintering (LS) parts with lower shrinkage rate.

Abstract: This paper examines the interfacial shear properties of a new fiber metal laminates based on oil palm fiber reinforced polypropylene. The adhesive shear strength based on two type of surface treatment technique had been studied to determine the best technique to ensure a good bonding for fiber metal laminates based on oil palm empty fruit bunch fiber reinforced polypropylene (EFB pp) composite and aluminium 6061. Adhesion between aluminum and EFB pp composite was achieved by incorporating modified polypropylene adhesive film and surface treatment of Al sheets. Differential Scanning Calorimetry test showed the suitable bonding temperature between the composite and glue to be between 140°C to 155°C which is lower than the melting temperature of polypropylene. The applied surface treatment of ethanol solvent wipe and NaOH chemical etch though have effect on the surface roughness but have no significant effect on the maximum adhesion shear stress. The modified polypropylene adhesive film selected for this work is suitable to bond EFB pp composite with aluminium 6061 and both surface treatment is equally suitable.

Abstract: The joint technology using ultrasonic welding is used to bond plastic material. Currently there are many researches to study the feasibility of using ultrasonic bonding to joint other materials. This paper reviewed the study on using ultrasonic bonding to joint multi metal, surface mount component, and textile material. The process configurations of each material are discussed and the results for each study are also presented. The multi metal materials bonding result shows that these materials bonded well to each other. The ultrasonic bonding strength for SMT components was as good as reflow oven and it was cosmetically accepted. The configuration of textile materials is investigated using vibrating ultrasonic horn and stationary anvil using high mechanical vibration and the result show it can be integrated ultrasonically. With advancement of computer control in ultrasonic welding, this technology can be used for any material in future to achieve world class manufacturing.

Abstract: This paper presents the influence of machining parameters namely cutting speed and feed rate on the machinability enhancement of AISI 316L stainless steel, in terms of surface integrity using end-milling with coated tungsten carbide tool (TiAlN). Optical microscopy, Scanning Electron Microscopy (SEM) and surface roughness measurement were used to analyze the surface integrity in terms surface topography and hardness test. A multi view approach is adopted to study the effect of different cutting parameters on the surface integrity of AISI 316L stainless steel. It was found that high cutting speed and low feed rate influence the surface roughness. Low surface roughness makes AISI 316L stainless steel more corrosion resistant which prevents wear of the implants.

Abstract: Dissimilar metal welding is widely applied to meet the rquirement of transition in mechanical properties and/or difference in working conditions. For instance, even though AISI 304 and AISI 316L are both belong to austenitic stainless steels, but they are applied in different working environment. AISI 304 is used at high temperature applications, whereas AISI 316L is used at low temperature. Repair welding is able to return a part back to its normal service life if weld failure happened due to service deterioration or defects during fabrication stage. However, repetitive heat input due to repair welding will cause changes in welded structure and properties. In this article, the effect of repetitive repair welding of dissimilar austenitic stainless steel pipes to the microhardness, tensile strength, microstructure and quality of the weldment has been reviewed.