Mohd Shahir Kasim

Modeling and Multi-Response Optimization on WEDM Ti6Al4V

Wire electrical discharge machining (WEDM) is a material removal process of electrically conductive materials by the thermo-electric source of energy which is extensively used in machining of materials for a highly precision productivity. This work presents the machining of titanium alloy (TI-6AL-4V) using WEDM with a brass wire diameter of 0.25mm.The objective of this work is to study the influence of three machining parameters, namely peak current (IP), feed rate (FC) and wire tension (WT) to cutting speed and surface roughness. Response Surface Methodology was used to develop second order model in order to predict cutting rate and surface roughness responses. The results showed that the average percentage error between the predicted and experimental value for both models was less than 2%.Furthermore, the developed models were used for multiple-response optimization by desirability function approach to determine the optimum machining parameters. These optimized machining parameters are validated experimentally, and it is observed that the response values are in good agreement with the predicted values.

The Effect of Pressure on Warpage of Dumbbell Plastic Part in Injection Moulding Machine

The optimization of processing parameters on warpage of polypropylene (PP) in the application of injection moulding machine was studied. The appropriate parameters were adjusted to reduce the warpage defect on the tensile test specimen of dumbbell. The type of injection moulding machine used in this research is Arburg 420C 800-250C. Four parameters that have been investigated; injection pressure, clamping pressure, back pressure and holding pressure. A concept of design of experiment (DOE) has been applied using Taguchi method to determine the suitable parameters. To measure the warpage of the dumbbell, digital height gauge was used to measure the flatness of the part surface. According the analysis of variance (ANOVA), the most significant factor that effect the warpage was holding pressure by 57.82%, followed with back pressure by 25.75%, clamping pressure by 16.27% and injection pressure by 0.16%. It is found that the optimum parameters setting that have been obtained were injection pressure at 950 bar, clamping pressure at 600 kN, holding pressure at 700 bar and back pressure at 75 bar. The depreciation value of warpage minimum index in this experiment was decreased by 4.6% after confirmation run.

Cutter Path Strategies for Shoulder Milling of Thin Deflecting Walls

The main problem associate with the machining of thin-wall component is the wall deflection which resulting in dimensional surface error that leads to part rejection. The magnitude of wall deflection is induced by the cutting force generated during the material removal process which is governed mainly from the selection of cutter path strategies. Therefore, it is necessary to judge the machining performance of a different cutter path prior to actual machining. In this paper, the machining accuracy of three cutter path strategies namely waterline-step, overlapping-step and tree wise-steps for machining thin-wall component were investigated. It was found that there is a variation in wall accuracy for different cutter path strategies. Based on the experimental results waterline cutter path produced the least surface error followed by overlapping and tree-wise steps.

Machining Parameters Optimization for Trimming Operation in a Milling Machine Using Two Level Factorial Design

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 (fr) and depth of cut (dc). 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 dc and fr 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, fr = 620 mm/min and dc = 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.

Cutting Performances of Coated PVD in High Speed End Milling of Aged Inconel 718

Inconel 718 is a material exhibiting characteristic that are able to maintain strength and integrity at elevated temperatures, but it is well known as a material with poor machinability. This paper presents a study of the performance in high speed machining of TiAlN/AlCrN nanomultilayer PVD coated Inconel 718 with minimum lubrication. Investigations have been made into the effects of cutting speed, feed rate and depth of cut (DOC) on the tool life. A toolmakers microscope and a scanning electron microscope (SEM) were used to examine the tool wear and chemical attrition, respectively, on the cutting tool during machining. In the machining of aged Inconel 718, the cutting tool experienced attrition, abrasion and notch wear throughout the experiment. Notch wear was found to be the dominant failure mode during milling; this wear appeared severe when localized flank wear reached the critical zone. The influence of radial depth despite the cutting speed, well known as having the most significant effect on tool life, is also discussed.

Evaluation of the Surface Integrity when Machining LM6 Aluminum Metal Matrix Composites Using Coated and Uncoated Carbide Cutting Tools

Metal matrix composite is composite material that combines the metallic properties of matrix alloys and additional element to reinforce the product. This paper evaluates the machining performance of uncoated carbide and coated carbide in terms of surface integrity during end milling of LM6 aluminium MMC. The parameter of cutting speed, feed rate and axial depth of cut were kept constant at 3000 rpm spindle speed, 60 mm/min feed rate and 0.5 axial dept of cut. The radial depth of cut were varied from 0.01mm to 0.1 mm. The results indicated that uncoated carbide show the better performance in terms of surface roughness and surface profile, as compared to coated carbide. On the other hand, coated carbide cutting tools suffered with built-up-edge formation at the tool edge, hence caused shearing effect and deterioration at the tool-chip interface. This study is expected to provide understanding of machining metal matrix composites based materials.

Cost evaluation on performance of a PVD coated cutting tool during end-milling of Inconel 718 under MQL conditions

Interest is currently being focused on promoting environmentally friendly manufacturing without sacrificing productivity by utilising a minimum quantity lubrication (MQL) as a biodegradable coolant in the end-milling of Inconel 718. This study was carried out to compare the costs of applying machining and lubrication to the end-milling process at various cutting conditions. The high-speed cutting of Inconel 718 was performed using response surface methodology, and the optimisation conditions of the physical vapour deposition TiAlN/AlCrN-coated carbide tool consumption and the MQL were evaluated according to the performance of the tool, i.e. machining time and material removed. In addition, the number of cutting tool edges was taken into consideration when calculating the machining cost. The machining performance at maximum tool life, the minimum surface roughness and force were compared with the optimum conditions, and the results showed that the application of MQL and the use of a ball nose end mill under optimum conditions are competitive. The multi-objective optimisation of cutting parameters, with regard to the criteria for the maximum material removed (9.029u2005cm3) and the lowest total cost (US

Modeling and Influence of Machining Parameters on Titanium Aloy

0.11u2005cm−3), provided a combination of parameters that met the requirements for green manufacturing, i.e. by reducing the usage of cutting tools and the consumption of lubrication.

Fatigue and Mechanical Properties of Graphene Nanoplatelets Reinforced Nr/Epdm Nanocomposites

Wire electrical discharge machining (WEDM) is a material removal process of electrically conductive materials by the thermo-electric source of energy which is extensively used in machining of materials for a highly precision productivity. This work presents the machining of titanium alloy (TI-6AL-4V) using WEDM with a brass wire diameter of 0.25mm.The objective of this work is to study the influence of three machining parameters, namely peak current (IP), feed rate (FC) and wire tension (WT) to cutting speed and surface roughness as a responses. Response Surface Methodology was used to develop second order model in order to predict cutting speed and surface roughness responses. The results showed that the average percentage error between the predicted and experimental value for both models was less than 2%. Effects of each parameter and their interaction with percentage contribution ratios (PCR) are included for each response.

Investigation of tangential force on ball nose rake face during high-speed milling of Inconel 718

Engine mounting suffers from fluctuating forces which may results in sudden failure due to fatigue. Graphene nanoplatelets have attracted great interest due to their exceptional physical, mechanical and thermal properties. Natural rubber/ethylene propylene diene monomer (NR/EPDM) reinforced with graphene nanoplatelets (GNPs) were investigated to improve the properties of NR/EPDM blend prior to fatigue and mechanical properties for engine mounting service. Firstly, the NR/EPDM blends and nanocomposite were tested for tensile properties and followed by the fatigue properties (tensile mode) using displacement-controlled. Tensile plot shows that the NR/EPDM nanocomposite has higher tensile value of 95% compared to NR/EPDM blend. The S-N curve illustrates that NR/EPDM blend and NR/EPDM nanocomposite break by the same cycle which is 100 000 cycles. The fracture behaviour of loading conditions was supported via morphological analysis using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis.