Papers by Keyword: Thrust Force

Abstract: Adaptive feed-rate controlled (AFC) drilling has been proposed as a high-quality and highly efficient drilling method for thermoplastic resins. The feed rate of the drill tool is controlled by the load in the thrust direction during AFC drilling. In the early stages of AFC drilling, the drill feed rate is extremely low, followed by a sudden increase in the drill feed rate. Experimental investigations revealed that the temperature near the drilling point had a dominant effect on the position at which the drill feed rate transitioned from low to high. The feed-rate transition temperature was approximately 150 °C for PA6. Therefore, the feed-rate transition position accelerated as the spindle speed increased, which significantly affected the cutting temperature. After the feed rate transitioned to a higher speed, drilling progressed at a constant rate. Additionally, the temperature of the drilled hole was generally constant regardless of the hole depth. One of the applications in which AFC drilling is expected to be superior is the drilling of different stacked materials. The effectiveness of AFC drilling was examined and compared with general constant-feed drilling for a stacked material of PA6 and carbon-fiber-reinforced thermoplastics. When the drilling efficiency was aligned, the maximum thrust force during AFC drilling was suppressed to less than 50% of that during general constant-feed drilling. Furthermore, the finished inner surface of the drilled hole was better after AFC drilling.

Abstract: A mechanical work piece created industrially frequently contains more than one machining process. Furthermore, it is a common activity of programmers, who make this selection every time a milling and drilling operation is conducted. Tool wear and borehole quality are two essential challenges for high precision drilling procedures, with Al 356 alloy being employed in experimental planning. Drilling specifications will be assessed in this work to get optimal parameters in minimizing the influence of drilling damage on alloy using a swarm-based optimization model. The drilling parameters are optimized using the Bacterial Foraging Optimization (BFO) method, which includes three control factors: depth, feed rate, and spindle speed. Each parameter is designed in three levels, with multiple performance characteristics such as thrust force, surface roughness, and delamination factor. This investigation was carried out in order to obtain the proper optimization. The feed rate, next to the spindle speed, was discovered to be the essential element inducing lamination in drilling, with this phenomenon occurring in each diameter of the drill bit. The results reveal that the feed rate and drill type are the most important parameters influencing the drilling process, and that employing this strategy can successfully improve drilling process outcomes.

Abstract: Most machining processes produce burr as a result of plastic deformation. Exit burr strongly affect product quality during assembly and it is difficult to remove them easily. This work aims at minimizing burr produced in drilling of Al6061/SiCp composite fabricated through stir-casting process using HSCO drill. Analysis of experimental results using ANOVA indicated the influence of cutting conditions and drill geometry in reducing the thrust force as well as burr size. Keywords: Drilling, Al6061/SiCp, HSCO drill, ANOVA, Thrust force, Burr

Abstract: Carbon fiber reinforced plastics (CFRP) has been widely used in various aircraft structural components. However, it is difficult for conventional methods such as drilling and helical milling to meet the requirements on high quality and efficient holes creation. Hence a so-called tilt helical milling (THM) method has been proposed. This new method is performed by replacing the revolving motion of the tool in conventional helical milling (CHM) with a conical pendulum motion, in which the tool axis is tilted towards the hole axis at a certain angle. As a step toward the establishment of the new method, in this work, the fundamental drilling characteristics of CFRP by the THM is elucidated by experimentally investigating the effects of tilt angle on thrust force and delamination factor. The obtained experimental results demonstrated that thrust force and delamination factor can be reduced with THM technique. In addition, THM can achieve better hole surface finish than CHM.

Abstract: The difficulties of machining nickel-titanium alloys are due to their high ductility and super-elasticity, strong strain-hardening, and excellent wear resistance. These characteristics lead to poor chip breakability, high cutting forces, rapid and aggressive tool-wear, as well as excessive burr formation during mechanical machining processes. The present study addresses these issues by evaluating the effects of drilling parameters and drill bit coatings on the growth of tool wear and development of the drilling thrust force. The findings from this research indicate that the TiAlN coated carbide drill was found to significantly improve the wear resistance of the cutting tool. Likewise, the results of thrust force development are consistent with the trends of tool wear growth for all of the tested carbide drills.

Abstract: Hole quality is one of the important criteria for hybrid composite components when assessing drilling behaviour because it influences the strength of composite parts post assembly. Nonetheless, some unique characteristics of hybrid Fibre-Reinforced Polymer (FRP) composites make them difficult to obtain the required quality and strict final dimensional accuracy. Based on previous studies, delamination has been recognized as one of the critical failure mechanisms in the drilling operation of FRP composites. It can often be the limiting factor for the final composite materials applications. Thus, in order to achieve a delamination-free in the drilling of hybrid FRP composites, an analytical model and a series of thrust force experiments are endeavoured in this study. The main purpose of the model is to compute the critical thrust force at the on-set of delamination during the drilling process. Results of this analytical study indicated that the delamination damage can be alleviated if the applied thrust force is lower than the critical thrust force value. Importantly, a good agreement was evident between the estimated critical thrust force and the measured thrust force in this particular study.

Abstract: Experiments were conducted with the main objective of improving the precision of drilling small-diameter, deep holes in austenite stainless steel (JIS SUS304). In the experiments, the step feed amount, rotation speed, and feed rate were varied and the thrust force and cutting temperature were measured to investigate the effect of cutting conditions on hole properties in drilling small-diameter deep holes. The results show that a combination of step feed amount and feed rate can reduce thrust force and drilling time, and that making the step feed small can suppress the cutting temperature.

Abstract: The need for eco-friendly materials and non-polluting processing techniques has made natural fibre reinforced polymer composites as potential candidates to replace GFRPS and CFRPS in semi structural applications. Ground nut shell and luffa fibre are easily available in the market at low cost. Polymer composites consisting of 30%, and 40% volume fractions of a hybrid reinforcement containing groundnut shell and luffa fibre in epoxy resin were fabricated by hand lay-up technique with varying process parameters, the variation in the mechanical properties such as tensile, compressive, flexure and impact strength are studied. The optimum mechanical properties were obtained in 40% of fiber volume fraction of treated fiber composites the machinability study was performed by drilling experiments using a drilling machine with drill tool dynamometer. Two input parameters, cutting speed and feed rate and the one output parameter, thrust force, were used for the drilling process. TiAlN coated solid carbide and hss drills were employed in the drilling experiments and a comparative study was made based on the output parameters. Solid carbide resulted in lower thrust force values and feed rate proved to be the most influential parameter on thrust force.

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.