Abstract: Machining of Carbon Fibre Composite (CFC), particularly drilling is frequently employed in many industries especially when dealing with joining, assembly and structural repair of the parts. This paper summarizes the properties of the CFC as well as the appropriate material and geometry of the cutting tool that should be used when drilling of the CFC in order to optimize the drilling performance. In addition, this work also presents the literature review on the relationship between cutting speed, feed rate, tool wear, thrust force and damage of the drilled CFC. The nature and heterogeneous structure of CFC often resulted in difficulty during their machining in terms of rapid tool wear and high thrust force. As a result, this always results in the damage of the drilled parts. Furthermore, higher cutting speed and lower feed rate are also recognized as significant factors which contribute to rapid wear of the cutting tool. Therefore, the use of tungsten carbide cutting tools, cutting fluids and cryogenic machining is seen to be a practical technique in optimizing the drilling performance involving CFC. In general, this work intends to provide a basic guideline and understanding regarding drilling of the CFC.
Abstract: This study investigates the tool wear of PVD TiAlN multilayer coated end mill inserts when machining AISI D2 hardened steel in dry conditions. The experiment tests consisting three levels of cutting speed, Vc (80, 100, 120 m/min) and three levels of radial depth of cut, ae (3, 4, 5 mm) was used for the study. The PVD TiAlN coated carbide insert performs satisfactory under the conditions tested, as reasonable tool life is recorded. By linking the machining tests and tool life curves, the wear behaviour of the coated insert was described. It is observed that wear of the tool mainly occurred on the flank wear. Tool life decreasing and volume material removal (VMR) increasing as cutting speed and radial depth of cut increased due to higher temperature generated and contact area immerse, respectively. Tool failure modes and wear mechanisms were examined at various cutting parameters. Built-up edge (BUE), groove and micro-chipping were found to be the predominant tool failure modes for cutting tools. The highest volume material removal, VMR attained was 3750 mm3, meanwhile the higest tool life, TL was 9.69 min.The combination of cutting conditions that gave the best response for different components of tool wear, tool life and surface integrity.
Abstract: Selection of the most suitable tool path strategy is very essential during machining especially in computer aided design and manufacture (CAD/CAM) as well as computer numerical control (CNC) machining. Existence of various tool path strategies to be applied on advanced composite materials such as aluminium epoxy required extensive researches in determining the best combination of tool path and cutting parameters for better machinability performance. Pocket milling of aluminium epoxy specimen via CAD/CAM was conducted in this study to investigate the effect of three types of tool path strategies namely Inward Helical, Outward Helical and Back and Forth. Uncoated high speed steel (HSS-Co8) ball end mill was used throughout the experiments. The machining responses that were evaluated include machining time, tool wear rate, tool life and surface finish of the machined pockets. In general, the effect of tool path strategy was highly significant on the machining responses and results showed that Back and Forth strategy offered the best machinability results when compared to the other strategies.
Abstract: The aim of this paper is to investigate the effect of cutting speed and uncut chip thickness on cutting performance. A Finite Element Method (FEM) based on the ABAQUS explicit software which involves Johnson-Cook material mode and Coulombs friction law was used to simulate of High Speed Machining (HSM) of AISI 1045 steel. In this simulation work, feed rate ranging from 0.05 mm/rev to 0.13 mm/rev and cutting speed ranging from 200 m/min to 600 m/min at three different cutting speeds were investigated. From the simulation results it was observed that increasing feed rate and cutting speed lead to increase temperature and stress distribution at tool/chip interface. The results obtained from this study are highly essential to predict machining induced residual stresses and thermo-mechanical deformation related properties on the machined surface.
Abstract: In this present work, the composite pressure vessel type three has been investigated by finite element method (FEM). The aluminum pressure vessel reinforced with Kevlar/Epoxy (Aramid 149) was analyzed under internal pressure to predict the ultimate failure pressure of the vessel. Also the optimum winding angle which provides the highest strength for the vessel was determined by applying Tsai-Wu and Tsai-Hill failure theories. The asymmetric fiber orientation for six different winding angles was utilized to reinforce the aluminum vessel. The commercial code ABAQUS/CAE was employed to analyze the composite vessel. Results obtained from the simulation were in good consistency with the analytical and the experimental outcomes.
Abstract: In this study, friction coefficients of different steel materials are investigated and compared. Experiments are carried out when different types of steel discs such as stainless steel 201 (SS 201), stainless steel 301 (SS 301) and mild steel slide against mild steel pin. Experiments are conducted at normal load 5, 7.5 and 10 N, sliding velocity 0.5, 0.75 and 1 m/s and relative humidity 70%. The effects of duration of rubbing on the friction coefficient of different steel materials are investigated. Results show that during friction process, test disc takes less time to stabilize with the increased normal load or sliding velocity. It is found that friction coefficient decreases with the increase in normal load while it increases with the increase in sliding velocity for all the tested materials. As a comparison, it is found that at identical operating conditions, friction coefficients are different for different steel materials depending on normal load or sliding velocity.
Abstract: This study focuses on the effect of foam quality on fill concentration during coil tubing cleanup operation. Thus, to quantify such effect, it is required to develop the numerical model to investigate the well cleaning. ANSYS CFX-14 is used for numerical study of fill transport in the horizontal well. A horizontal well geometry (5.76"×3.5" concentric annulus) was created for fill concentration analysis. Present study is carried out with 70, 80 and 90% quality at four different velocities 3, 4, 5 and 6 ft/sec. The results indicated that the 90% quality foam was good even at low velocity.
Abstract: The use of aluminium alloy in the manufacturing industry has increased tremendously in the past decade mainly in the areas of aeronautics and automobiles. The ease of machinability of this material makes it a more desirable operand in manufacturing usage. Hence, in this research, a study was undertaken to perform a comparative analysis of dry and cold air drilling on 6061 aluminium alloy. The drill tool used in the drilling process was HSS Cobalt coated tool which has not featured in many research papers. Subsequently, the quality of each hole was identified based on the diameter accuracy of the hole and the surface roughness of the hole. A variation in the parameters was employed to identify the best feed rate and spindle speed that can accommodate a quality hole. In addition, during the drilling operations, force was measured to analyse the ensemble of parameters that present the highest and lowest force. Based on the data collected, an analysis was performed to identify the best quality hole. The force measured for cold air drilling was relatively lower than those measured in dry drilling primarily when high feed rate of 80 mm/min and high speed of 6000 rpm is used. The surface roughness and hole diameter does not differ much between cold air and dry drilling. Therefore, it is highly recommended that feed rate of 80 mm/min coupled with a spindle speed of 6000 rpm be used for drilling operations with a 5mm diameter tool.
Abstract: Shape of workpiece, electrode orientation and flushing system play important role in electrical discharge machining (EDM) process. Low material removal rate and relatively high electrode wear ratio are some of the disadvantages of EDM process. This can be due to the flushing modes. Workpiece shape has a significant effect in effectiveness of dielectric flushing flow and orientation during EDM process. This research work is conducted to analyze the influence of various workpiece shapes. Square cavity, L shape, flat shape and U shape were machined with same cross-section electrode material. Test parameters are material removal rate (MRR) and electrode wear ratio (EWR). Experiment results show slight difference in MRR and EWR values for different shapes. U shape presents the highest MRR and the lowest EWR occurs in flat shape compared to cavity and L shapes. It can be concluded that flat and U shapes result in good EDM machining quality due to good dielectric flow and flushing conditions in the area of EDM machining.