Papers by Keyword: Drilling

Abstract: AA 2024 alloy is widely used as a structural material in aerospace applications. Its excellent strength to weight ratio makes it suitable for the subsequent application. The aerospace application required close tolerances and accuracy in the machined parts. Henceforth non-conventional machining processes are widely used for different machining operations such as drilling through holes. In the present study, Electrical Discharge Machining (EDM) process is used to drill through holes in 5mm thick AA 2024 alloy material. With the aim of reducing the difference between finished diameter of drilled hole and intended diameter, computational technologies were adopted for optimization. Mathematical models were developed using Response Surface methodology (RSM), and subsequently Genetic Algorithm (GA) was used to reach a set of input parameters in order to give minimum difference in diameter. Three input parameters such as current (I), Pulse on time (Ton) and Pulse off time (Toff) were selected. The ANOVA results indicated that developed models were adequate and robust. The GA based approach in conjugation with RSM was able to locate a single set of parameters which gave minimum difference in diameter. Confirmation test was again carried out and the difference between predicted and measured value was negligible.

Abstract: Composite laminates are used in many applications in industries like aerospace and aircraft due to their extremely high strength to weight ratio and corrosion resistance properties. The composite laminates are difficult to machine materials, which results into low drilling efficiency and drilling-induced delamination, thus it is important to develop a suitable CFRP material with different ply orientation to overcome the difficulties related in machining of composite materials. The focus of present work presents a comparative study involving experimental characterization with different ply orientation to understand the effect of cutting parameters on the thrust force, delamination extent and exit hole diameter during conventional drilling of carbon fiber reinforced polymer. Processing parameters such as, feed rate plays dominant role in delamination than spindle speed in both ply orientation. The analysis shows that conventional drilling with [0/90]16 ply yields lower delamination and hole size variation than [(0/45/90/-45)]4s ply orientation.

Abstract: Titanium alloy Ti6Al4V represents one of the most frequently used alloys in medical as well as in aerospace industry and is considered as a difficult to cut material. In this paper, cutting experiments within throughput drilling were carried out under the varying cutting speed, feed and tool geometry (cutting edge radius and clearance angle). The effects of cutting speed feed and tool geometry on thrust force in drilling Ti6Al4V alloy were investigated applying design of experiment (DoE) according to Taguchi plan L₁₆. The effect of above mentioned parameters was investigated through analysis of the S/N ratios (smaller is better) and ANOVA analysis. All analyses were performed using statistical software Minitab and Matlab. In the case of thrust force, the feed is the main influencing factor, followed by cutting speed, cutting edge radius and clearance angle.

Abstract: Bone drilling is often used in trauma care, orthopedic and other type of surgical procedures. The elevated temperatures caused by friction may lead to temperature induced bone necrosis. This paper presents an analysis of the effect vibration assisted drilling has on the drilling temperature of the compact bone.The experimental setup was developed and two-type experiments have been conducted. The main aim was to analyze the low frequency vibrations assisted drilling effect on the drilling temperature of poly-methyl methacrylate (PMMA) and bone samples. The temperatures at the exit hole were measured using the thermal camera. The rotational speed of the drill, applied force, parameters of the drill and the samples were considered as constant, whereas the amplitude and frequency of vibrations were varied during the experiments. The obtained experimental data showed the decrease in the drilling temperatures of the vibrated bone samples, as compared to the conventional drilling. It should be noted that further investigation and research related to the vibration assisted drilling should be carried out using different type of bone samples and experimental conditions.

Abstract: The origin of drilling force in drilling with twist drill is quite complicated owning to the complex shape of the drill bit cutting edges. In this paper, the drilling experiments both with and without the ultrasonic were designed and conducted on aluminum alloy with pre-drilled hole. The drilling force was tested and the different effects between the cutting edges of the twist drill on the drilling force were analyzed under various drilling parameters including the spindle speed, feed rate and vibration amplitude. The drilling force of conventional drilling (CD) and ultrasonic assisted drilling (UAD) was characterized and the roles of the ultrasonic vibration in drilling were discussed.

Abstract: A research was conducted for the optimization in the drilling process of KFRP stacked, with multiple performance characteristics based on the orthogonal array with Taguchi-grey-fuzzy method. The experimental study was conducted under varying the drilling process parameters (feeding speed (mm/min) and cutting speed (m/min)) and tool geometries (point geometry and point angle (degree)). The optimized multiple performances characteristics were thrust force, torque and surface roughness. The quality characteristics of thrust force, torque and surface roughness were smaller-is-better. The experimental design used L₁₈ orthogonal array with two replications. Experimental results have shown that machining performance in the drilling process can be improved effectively through this method.

Abstract: Accurate and strong fastener assembly depends on precision of the hole. For structural material likes composites, these criteria is very important. Drilling is the most common method in producing hole on composites. But the main problem of drilling is excessive tool wear that may affect the quality of the holes. Punching is another alternative in making a hole. The main objective of this study is to compare between drilling and punching in terms of hole quality. The scanned images of the produced hole will be captured using commercial 3D optical surface measurement method namely Alicona IFM. The effect to the quality of the produced hole will be measured and compared between drilling and punching.

Abstract: Drilling process has many applications including making molds and dies, all requires different quality of the drilled hole. The aim of this study is to establish models and optimization of cutting parameter to get the best hole quality, including enlargement diameter, circularity error and surface roughness in drilling hardened steel. Drilling experiments have been performed using different cutting parameters (i.e. cutting speed and feed rate) and employ and uncoated carbide drill under flooded cooling. The experimental results show that both of the cutting speed and feed rate significantly affect all responses. Models for responses have been developed for investigation in this study, and their optimizations have been obtained, showing better quality of the drilled hole produced at higher cutting speed and lower feed rate. Desirability for the optimum criteria is 0.944 at the highest cutting speed (60 m/min) and lowest feed rate (0.05 mm/rev).

Abstract: In this work, a set of active learning activities has been presented. These tasks are focused on the design and implementation of online activities for students of Mechanical Engineering Degree, in order to fulfill specific and generic competences in the field of manufacturing engineering, and in particular in machining processes. For this purpose, the students have conducted simulations using finite elements method, through Deform 3D software, and it has been applied to the drilling process of the composite with polymeric matrix, polyether-ether-ketone reinforced with glass fibre in 30%, PEEK-GF30. The results show data of variables as thrust force and torque, and others relate to online activities and skills acquired by students when they perform the tasks in a virtual platform. These type of activities motive to students and allow knowing the behavior of materials on a more attractive manner.

Abstract: The cutting heat, during the process of drilling fiber reinforced resin matrix composites, has a significant effect on the quality and the tool wear. In this paper, based on the homogenization hypothesis of the material and the finite difference method, a temperature field model for drilling unidirectional Kevlar composites was developed. During the drilling process, the heat source formed by cutting edge and chisel edge can be seen as a conical heat source. The results show that the temperature field distribution is ellipse away from the drilling zone with the longer axis paralleling to the fiber direction and changes close to the drilling zone.