The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
C C Tsao - One of the best experts on this subject based on the ideXlab platform.
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evaluation of drilling parameters on thrust force in drilling carbon fiber reinforced plastic cfrp composite laminates using compound core special drills
International Journal of Machine Tools & Manufacture, 2011Co-Authors: C C Tsao, Y C ChiuAbstract:Abstract Drilling is the mostly used secondary machining of the fiber reinforced composite laminates, while the delamination occurs frequently at the drill exit in the workpiece. In the industrial experiences, core drill shows better drilling quality than twist drill. However, chip removal is a troublesome problem when using the core drill. Conventional compound core-special drills (core-special drills and step-core-special drills) are designed to avoid the chip removal clog in drilling. But the cutting velocity ratio (relative motion) between outer drill and inner drill is null for conventional compound core-special drills. The current study develops a new device and to solve the problems of relative motion and chip removal between the outer and inner drills in drilling CFRP composite laminates. In addition, this study investigates the influence of drilling parameters (cutting velocity ratio, feed rate, stretch, inner drill type and inner drill diameter) on thrust force of compound core-special drills. An innovative device can be consulted in application of compound core-special drill in different industries in the future.
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effect of tool wear on delamination in drilling composite materials
International Journal of Mechanical Sciences, 2007Co-Authors: C C Tsao, H HochengAbstract:Among all machining operations, drilling using twist drill is the most frequently applied for secondary machining of composite materials owing to the need for structure joining. Delamination is mostly considered as the principal failure model in drilling of composite materials. Drill wear is a serious concern in hole-making industry, as it is necessary to prevent damage of cutting tools, machine tools and workpieces. The industrial experience shows the worn drill causes more delamination. This paper presents a comprehensive analysis of delamination caused by the drill wear for twist drill in drilling carbon fiber-reinforced composite materials. The critical thrust force at the onset of delamination for worn drill is predicted and compared with that of ideal drill. The experimental results demonstrate that though the critical thrust force is higher with increasing wear ratio, the delamination becomes more liable to occur because the actual thrust force increases to larger extent, as the thrust factor (Z) illustrates. Compared to sharp drill, the worn twist drill allows for lower feed rate below which the delamination damage can be avoided.
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effects of special drill bits on drilling induced delamination of composite materials
International Journal of Machine Tools & Manufacture, 2006Co-Authors: H Hocheng, C C TsaoAbstract:Drilling is the most frequently employed operation of secondary machining for fiber-reinforced materials owing to the need for joining structures. Delamination is among the serious concerns during drilling. Practical experience proves the advantage of using such special drills as saw drill, candle stick drill, core drill and step drill. The experimental investigation described in this paper examines the theoretical predictions of critical thrust force at the onset of delamination, and compares the effects of these different drill bits. The results confirm the analytical findings and are consistent with the industrial experience. Ultrasonic scanning is used to evaluate the extent of drilling-induced delamination. The advantage of these special drills is illustrated mathematically as well as experimentally, that their thrust force is distributed toward the drill periphery instead of being concentrated at the center. The allowable feed rate without causing delamination is also increased. The analysis can be extended to examine the effects of other future innovative drill bits.
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effect of eccentricity of twist drill and candle stick drill on delamination in drilling composite materials
International Journal of Machine Tools & Manufacture, 2005Co-Authors: C C Tsao, H HochengAbstract:Drilling is the most frequently employed operation of secondary machining for fiber-reinforced materials owing to the need for structure joining. Delamination is one of the serious concerns during drilling. Practical experience shows that an eccentric twist drill or an eccentric candle stick drill can degrade the quality of the fiber reinforced material. Comprehensive delamination models for the delamination induced by an eccentric twist drill and an eccentric candle stick drill in the drilling of composite materials have been constructed in the present study. For an eccentric twist drill and an eccentric candle stick drill, the critical thrust force that will produce delamination decreases with increasing point eccentricity ξ. The results agree with industrial experience. The need for control of drill eccentricity during drill regrinding has been proved analytically by the proposed models.
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comprehensive analysis of delamination in drilling of composite materials with various drill bits
Journal of Materials Processing Technology, 2003Co-Authors: H Hocheng, C C TsaoAbstract:Abstract Beside the twist drill, the effects of various drill geometries were rarely discussed in analytical fashion. This study presents a comprehensive analysis of delamination in use of various drill types, such as saw drill, candle stick drill, core drill and step drill. In this analysis, the critical thrust force at the onset of delamination is predicted and compared with the twist drill.
H Hocheng - One of the best experts on this subject based on the ideXlab platform.
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effect of tool wear on delamination in drilling composite materials
International Journal of Mechanical Sciences, 2007Co-Authors: C C Tsao, H HochengAbstract:Among all machining operations, drilling using twist drill is the most frequently applied for secondary machining of composite materials owing to the need for structure joining. Delamination is mostly considered as the principal failure model in drilling of composite materials. Drill wear is a serious concern in hole-making industry, as it is necessary to prevent damage of cutting tools, machine tools and workpieces. The industrial experience shows the worn drill causes more delamination. This paper presents a comprehensive analysis of delamination caused by the drill wear for twist drill in drilling carbon fiber-reinforced composite materials. The critical thrust force at the onset of delamination for worn drill is predicted and compared with that of ideal drill. The experimental results demonstrate that though the critical thrust force is higher with increasing wear ratio, the delamination becomes more liable to occur because the actual thrust force increases to larger extent, as the thrust factor (Z) illustrates. Compared to sharp drill, the worn twist drill allows for lower feed rate below which the delamination damage can be avoided.
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effects of special drill bits on drilling induced delamination of composite materials
International Journal of Machine Tools & Manufacture, 2006Co-Authors: H Hocheng, C C TsaoAbstract:Drilling is the most frequently employed operation of secondary machining for fiber-reinforced materials owing to the need for joining structures. Delamination is among the serious concerns during drilling. Practical experience proves the advantage of using such special drills as saw drill, candle stick drill, core drill and step drill. The experimental investigation described in this paper examines the theoretical predictions of critical thrust force at the onset of delamination, and compares the effects of these different drill bits. The results confirm the analytical findings and are consistent with the industrial experience. Ultrasonic scanning is used to evaluate the extent of drilling-induced delamination. The advantage of these special drills is illustrated mathematically as well as experimentally, that their thrust force is distributed toward the drill periphery instead of being concentrated at the center. The allowable feed rate without causing delamination is also increased. The analysis can be extended to examine the effects of other future innovative drill bits.
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effect of eccentricity of twist drill and candle stick drill on delamination in drilling composite materials
International Journal of Machine Tools & Manufacture, 2005Co-Authors: C C Tsao, H HochengAbstract:Drilling is the most frequently employed operation of secondary machining for fiber-reinforced materials owing to the need for structure joining. Delamination is one of the serious concerns during drilling. Practical experience shows that an eccentric twist drill or an eccentric candle stick drill can degrade the quality of the fiber reinforced material. Comprehensive delamination models for the delamination induced by an eccentric twist drill and an eccentric candle stick drill in the drilling of composite materials have been constructed in the present study. For an eccentric twist drill and an eccentric candle stick drill, the critical thrust force that will produce delamination decreases with increasing point eccentricity ξ. The results agree with industrial experience. The need for control of drill eccentricity during drill regrinding has been proved analytically by the proposed models.
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comprehensive analysis of delamination in drilling of composite materials with various drill bits
Journal of Materials Processing Technology, 2003Co-Authors: H Hocheng, C C TsaoAbstract:Abstract Beside the twist drill, the effects of various drill geometries were rarely discussed in analytical fashion. This study presents a comprehensive analysis of delamination in use of various drill types, such as saw drill, candle stick drill, core drill and step drill. In this analysis, the critical thrust force at the onset of delamination is predicted and compared with the twist drill.
Elaheh Ghassemieh - One of the best experts on this subject based on the ideXlab platform.
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numerical investigation of the effects of drill geometry on drilling induced delamination of carbon fiber reinforced composites
Composite Structures, 2013Co-Authors: Ozden Isbilir, Elaheh GhassemiehAbstract:Abstract Drilling is a major process in the manufacturing of holes required for the assemblies of composite laminates in aerospace industry. Simulation of drilling process is an effective method in optimizing the drill geometry and process parameters in order to improve hole quality and to reduce the drill wear. In this research we have developed three-dimensional (3D) FE model for drilling CFRP. A 3D progressive intra-laminar failure model based on the Hashin’s theory is considered. Also an inter-laminar delamination model which includes the onset and growth of delamination by using cohesive contact zone is developed. The developed model with inclusion of the improved delamination model and real drill geometry is used to make comparison between the step drill of different stage ratio and twist drill. Thrust force, torque and work piece stress distributions are estimated to decrease by the use of step drill with high stage ratio. The model indicates that delamination and other workpiece defects could be controlled by selection of suitable step drill geometry. Hence the 3D model could be used as a design tool for drill geometry for minimization of delamination in CFRP drilling.
Kingshook Bhattacharyya - One of the best experts on this subject based on the ideXlab platform.
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artificial neural network based prediction of drill flank wear from motor current signals
Applied Soft Computing, 2007Co-Authors: Karali Patra, Surjya K Pal, Kingshook BhattacharyyaAbstract:In this work, a multilayer neural network with back propagation algorithm (BPNN) has been applied to predict the average flank wear of a high speed steel (HSS) drill bit for drilling on a mild steel work piece. Root mean square (RMS) value of the spindle motor current, drill diameter, spindle speed and feed-rate are inputs to the network, and drill wear is the output. Drilling experiments have been carried out over a wide range of cutting conditions and the effects of drill wear, cutting conditions (speed, drill diameter, feed-rate) on the spindle motor current have been investigated. The performance of the trained neural network has been tested for new cutting conditions, and found to be in very good agreement to the experimentally determined drill wear values. The accuracy of the prediction of drill wear using neural network is found to be better than that using regression model.
Faruk Karaca - One of the best experts on this subject based on the ideXlab platform.
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influence of drill parameters on bone temperature and necrosis a fem modelling and in vitro experiments
Computational Materials Science, 2012Co-Authors: S Sezek, Bunyamin Aksakal, Faruk KaracaAbstract:Abstract During drilling of bone, excessive heat may cause thermonecrosis and this weakens the purchase of surgically placed screws and pins thus reduces the success of subsequent fixation and implantation process. In order to minimise the problems caused by high temperature (above 45 °C) in bone drilling operations, it is necessary to operate with optimum cutting and drilling parameters. This study analysis the temperature changes during cortical bone drilling for different parameters such as drill rotation speed, feed-rate, drill diameter, drill force, bone mineral density and bone sex via the finite element method, FEM. The analysis have been validated by in vitro experiments using fresh calf cortical bones. Analytical and experimental results showed that the safe drilling parameters and drill temperatures can be estimated. To avoid thermal necrosis, the safe drilling zones (below 45 °C) have been determined for various drill parameters during drilling of fresh cortical bones. Temperature increased 10% with 12% increase in bone mineral density and the safe drill parameters obtained to be 370 rpm drill speed, 70 mm/min feed rate and 140 N drill force.
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influence of drill parameters on bone temperature and necrosis a fem modelling and in vitro experiments
Computational Materials Science, 2012Co-Authors: S Sezek, Unyami Aksakal, Faruk KaracaAbstract:Abstract During drilling of bone, excessive heat may cause thermonecrosis and this weakens the purchase of surgically placed screws and pins thus reduces the success of subsequent fixation and implantation process. In order to minimise the problems caused by high temperature (above 45 °C) in bone drilling operations, it is necessary to operate with optimum cutting and drilling parameters. This study analysis the temperature changes during cortical bone drilling for different parameters such as drill rotation speed, feed-rate, drill diameter, drill force, bone mineral density and bone sex via the finite element method, FEM. The analysis have been validated by in vitro experiments using fresh calf cortical bones. Analytical and experimental results showed that the safe drilling parameters and drill temperatures can be estimated. To avoid thermal necrosis, the safe drilling zones (below 45 °C) have been determined for various drill parameters during drilling of fresh cortical bones. Temperature increased 10% with 12% increase in bone mineral density and the safe drill parameters obtained to be 370 rpm drill speed, 70 mm/min feed rate and 140 N drill force.
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influence of orthopaedic drilling parameters on temperature and histopathology of bovine tibia an in vitro study
Medical Engineering & Physics, 2011Co-Authors: Faruk Karaca, Bunyamin Aksakal, Mustafa KomAbstract:Orthopaedic drilling operations without optimum operating parameters by surgeons may cause bone defects such as bone fracture, cracks, osteolysis and tissue loss around the drilling zone. For the sake of optimum drilling parameters, an in vitro study was performed by considering the bone mineral density, bone sex, drill tip angle, drill speed, drill force and feed-rate. The specimens were taken from the drilled sites of fresh male and female calf tibias. The temperature changes at the drill site were investigated throughout the statistical and histopathological analysis. It was observed that the temperature increased with an increasing drill speed and decreased with high feed-rates and applied drill forces. The drilling temperatures of the female bovine tibias were found to be higher than that of the male tibias and the drill speed was found to be a significant parameter on the maximum temperature. Moreover, the maximum temperature increased with an increasing drill tip angle and bone mineral density. Therefore the bone quality around the drill site was found to be worse than the bone samples exposed to low temperatures.
