Applied Mechanics and Materials Vols. 766-767

Abstract: Natural fibre composites today are replacing synthetic fibre composites due to superior properties of natural fibres such as low density, high specific strength and modulus, relative no abrasiveness, ease of fibre surface modification, and wide availability .Drilling is often required to facilitate the assembly of the parts to get the final product. however, drilling composite materials present a number of problems such as delamination associated with the characteristics of the material and with the used cutting parameters .The present investigation is an attempt to study the factors and combination of factors that influence the delamination of drilled unidirectional jute fibre reinforced composites using taguchi, signal to noise ratio, Anova analysis and to achieve the conditions for minimum delamination.

Abstract: In the present paper, the experimental investigations on drilling characteristics of cenosphere reinforced epoxy composites with cemented carbide drill have been presented. The drilling aspects such as thrust and hole surface roughness have been performed as function of four process parameters, namely, spindle speed, feed rate, drill diameter and % weight of the filler. Composite specimens were prepared with 20%, 40% and 60% by weight of cenosphere filler in epoxy resin as the matrix. The full factorial design (FFD) has been employed for conducting drilling experiments and the proposed drilling characteristics were analysed using response surface methodology (RSM) based quadratic models. The response surface analysis reveals that the addition of cenosphere as filler in epoxy resin appreciably decreases with the thrust and hole surface roughness for the developed composites.

Abstract: The present research investigates the damage during drilling of natural sandwich composites. Three composite samples were prepared by using reinforcements namely vetiver, jute and glass in vinyl ester as matrix. Drilling operations were done on the composites and responses namely damage factor and surface roughness were measured. The responses were optimized in order to get optimal running conditions. Fuzzy modelling was done and its predictions of responses for experimental conditions were examined. A comparative analysis between the experimental, model and fuzzy was done. Confirmatory trials were made for optimum conditions and the responses were measured. Model validation was done by measuring the average error between the model and confirmatory and between the model and fuzzy. The errors were minimal and hence the optimization was accurate.

Abstract: The objective of the study is to conduct experiments to investigate the performance of Electrochemical Micromachining (EMM) process to drill micro-holes on Copper alloy and analyze the parameters to optimize by Taguchi method. An EMM setup developed in-house is used to conduct the experiments. Copper alloy as workpiece, Stainless Steel needle of sharp conical edge as tool and Sodium Nitrate as electrolyte are used. A Pulse generator is used to supply pulsed current. The input parameters analyzed for optimization are Voltage, Pulse on-time and Electrolyte Concentration. The Material Removal Rate (MRR) and Overcut are taken as output parameters to study the process performance. The experiment was designed according to L9 Orthogonal Array (OA) of Taguchi design. The observations have shown that the MRR increases and the accuracy decreases when the level of input value for any parameter is increased. The process parameters are optimized using Taguchi Analysis.

Abstract: Wood composite panels are widely used in construction and furniture industries. They are very much preferred in interior and exterior decoration, house hold products and toys, etc. because of the aesthetic appearance and their high-quality properties. In manufacturing of wood composite products various machining process are used. In final assembly of various parts of a end product, drilling is the most commonly used machining operation. The cutting forces developed during drilling process having more effect on the surface quality of the drilled holes. Hence the drilling damages like delamination must be controlled to ensure the surface quality of the final product. In controlling these forces the contribution of input drilling parameters is more. The objective of this work is to study the influence of input control parameters to obtain the optimal cutting conditions. In the present study the drilling experiments are performed using Taguchi design of experiments with Taguchi L₂₇ orthogonal array on particleboard (PB) composite panels using high speed steel (HSS) twist drills with three different drill diameters. Response surface methodology (RSM) is used to develop a mathematical model to predict the influence of input control parameters on delamination. The adequacy of the model is checked using Analysis of variance. It is revealed that high spindle speed with low feed rate and smaller drill diameter combination gives better results.

Abstract: Medium density fiberboard wood composite panels are preferred for many domestic and industrial applications over the natural wood because of their high-quality properties. The aesthetic appearance of wood composites makes them suitable for interior and exterior construction works. Among various machining process, drilling is the most frequently used machining operation in the furniture industry in assembly of panel products. During drilling process the drill exhibits cutting forces such as thrust force and torque. The surface quality of the drilled holes are mainly affected by the cutting forces developed during drilling process which causes surface roughness, delamination like damages which leads to the rejection of the final product. Hence the reduction of the drilling defects, the control of the cutting forces is very much essential. The drilling parameters play an important role in controlling the cutting forces. The objective of this work is to study the influence of input control parameters such as spindle speed, feed rate and point angle on surface roughness in drilling of MDF panels to obtain the optimal cutting conditions. In the present study the drilling experiments are conducted using Taguchi design of experiments on wood composite panels with high speed steel (HSS) twist drills with different point angles on vertical machining center using at dry condition. Three levels and three factors are considered. Taguchi L₂₇ orthogonal array is used. Response surface methodology is used to develop a mathematical model to predict the influence of input control parameters on cutting forces. Analysis of variance is used to check the adequacy of the model. Surface roughness is increased with an increase of feed rate and drill point angle and decreased with an increase in the spindle speed. It is revealed that high spindle speed with low feed rate and smaller point angle combination gives better results in drilling of wood composite panels.

Abstract: Metal matrix composites (MMCs) possess significantly improved properties including high strength to wear ratio, high modulus, superior wear resistance and corrosion resistance compared to unreinforced alloys. In spite of the advantages, the Aluminium based metal matrix composites have not yet found a wide employment in the commercial applications, because the the matrix cause serious problems in machining / drilling, such as high drilling forces, tool wear, and poor surface finish due to the hard particles. The drilling of Al/SiC metal matrix composite has received a serious attention for many years. Different specimens were prepared from Aluminium / Silicon carbide (Sic) metal matrix composites by stir casting method by varying the weight percentage of Sic and the investigation has been carried out on the specimen by drilling holes on them. Surface finish is an important factor to be taken into account in the drilling process. So, it is more necessary to predict the average surface roughness of the materials. Then the roughness of the drilled holes made on the specimen was studied using Atomic force microscope. The investigation was carried out with their characteristics being studied by comparing various parameters such as cutting speed, feed rate and so on. The average roughness was studied on 30µm X 30µm and 15 µm X 15µm horizontal section and vertical section. Their histograms were also studied.

Abstract: In this paper, the damage of drilling parameters on roundness error is investigated in drilling of Glass Fiber Reinforced Polypropylene (GFR/PP) matrix composites with ‘Brad and Spur’ drill bit. The experiment is carried out using Solid Carbide drill bit and L27 orthogonal array is used to analyze the effect of spindle speed, feed rate and drill diameter. A complete and in-detail evaluation and optimization of cutting parameter using Box-Behnken Design (BBD) technique is carried out. The design is contributed for quality and productivity equally and analysis of the drilling parameters. The roundness error is determined using response surface methodology (RSM) and Analysis of variance (ANOVA) which is used for analyzing the output results. One of the most important ovalty damage to be controlled on a cylindrical drilled part is the roundness error. The Co-ordinate Measuring Machine (CMM) is the general metrological equipment used for inspection of roundness error which is normally performed in a quality room. The results indicated that the model can be effectively used for predicting the response variable by means of which roundness error can be controlled. 3-D response surface graphs are developed to study the effect of drilling parameters with roundness error and presented in detail.

Abstract: This study presents an experimental investigation on the effects of cutting speed, feed and percentage of alumina particle on the burr height in drilling of Al 6063 reinforced with Al₂O₃ and Gr particles using solid carbide twist drills of 6 mm diameter. Taguchi method with three factors at three levels is employed to analyze the drilling characteristics of these composites. For all cutting conditions, Al 6063/6%Al₂O₃/1%Gr composite has lower burr height values than other fabricated composites. The results revealed that exit hole burr height are greatly influenced by the feed rate rather than the speed for all the samples of hybrid composites.

Abstract: It is very tedious process to find the optimum multiple performance measures of wire EDM process parameters and role of each parameter to attain the better performance characteristics. Since the WEDM process involves more one than machining characteristics, it is important to carry out the multi-response optimization methodology. In the present study, an attempt has been made to find the optimum process parameters using Taguchi-Grey relational analysis. The machining experiments have been conducted with different levels of input factors such as voltage, peak current, pulse on time, and pulse off time and wire material based on Taguchi L₁₈ orthogonal table. Experimental results have indicated that the multi-response characteristic such material removal rate and surface roughness can be enhanced by 1.2% effectively through grey relational analysis.