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The effect of pre-drilling on the characteristics of friction drilled A356 cast aluminum alloy
Abstract
Hardness Bushing Surface roughness Microstructure SEM A B S T R A C T The friction drilling process utilizes frictional heat to increase the thickness of sheet metal parts by making holes with bushes using a non-traditional drilling tool. Unfortunately, cracks are found in the formed bushings during friction drilling of brittle materials. The purpose of the present study is to improve the quality of friction-induced bushes in brittle A356 aluminum sheets via a performance of a pre-drilling with different diameters (2, 2.5, and 3 mm). The pre-drilling is aimed to reduce cracks and petal formation as compared with the solid sheets. The friction drilling processes were carried out by a K100 conical tool, with 10 mm diameter and 58 • cone angle. The friction drilling parameters involve different rotational speeds (2000, 3000, and 4000 rpm) as well as different feed rates (40, 60, and 80 mm/min). The characteristics of the thermally induced bushes (shape, dimensions, and surface roughness) were investigated in solid and pre-drilled sheets. Furthermore, we studied the microstructure evolution and hardness distribution in the thermo-mechanical affected zone and the heat-affected zone surrounding the bush. It was found that, the formed bushings in the pre-drilled sheets did not have cracks or petal formation in comparison with the other formed bushes in the solid sheets. The pre-drilled specimens showed an average bushing height increase from 5 to 6 ± 0.8 mm with the increase of the tool rotational speed from 2000 to 4000 rpm. At rotational speeds of 2000 and 4000 rpm, the pre-drilled specimens with a diameter of 2.5 mm had a bushing height which is 0.5 ± 0.2 mm greater than the other pre-drilled specimens. In addition, the surface roughness of the pre-drilled sheets decreased with the increase of the rotational speed and/or reduction of the feed rate. Moreover, the microstructure near the drilling zone exhibited a fine Si particles distribution. However, the hardness values near the drilled surfaces were 15 ± 8 HV lower than those of the base metal in both solid and pre-drilled sheets.
... It illustrates that the precipitates existing within the microstructure can be categorized into two distinct types: engraved (highlighted in blue) and bulged (highlighted in orange). Within the SZ, the precipitates are homogeneously distributed throughout the microstructure, which agrees with the findings reported in the literature [35]. Moving to the TMAZ, as shown in Figure 5.c, there is a vertical alignment of grains oriented in the same direction as the movement of the drilling tool. ...
... These grains exhibit a layered structure reminiscent of onion rings, with layer sizes ranging between 25 and 50 μm. This phenomenon, known as the "onion ring structure" is commonly associated with the stirring effect induced by the drilling tool [35]. is in alignment with the results presented in the literature [42]. ...
... This finer structure is indicative of the homogenizing effect of the friction drilling process within the SZ, which agrees with the results presented recently by Albarabary et al. [35]. This change in composition suggests that the severe plastic deformation during the friction drilling process played a crucial role in promoting the homogeneous distribution of silicon particles within the α-aluminum matrix, mainly due to the stirring effect generated during friction drilling. ...
... It is apparent that t values are dependent on the rotational speed and feed rate more than the tool cone angle and has increased with the rise in RS and FR values. Since at high rotational speed values, more heat is generated [2], which results in a softening of the material, and consequently, the thickness of the produced bush increases, and this agrees with the literature [28]. ...
... Figure 10 shows the microstructure of specimen R10. Clearly, the friction drilling process resulted in the appearance of three different zones, namely the drilling zone (DZ), the thermo-mechanically affected zone (TMAZ), and the heat-affected zone (HAZ), in addition to the base metal (BM); this agrees with the literature [28]. The DZ is the area in direct contact with the tool. ...
Thermal drilling is a non-traditional, chip-less, and green hole-forming process affected by the drilling tool rotational speed (RS), feed rate (FR), and drilling tool cone angle (β). The present investigation studies the effect of variations in friction drilling parameters (RS and FR, as well as the cone angle β) on the surface roughness values and the dimensions (height and thickness) of the thermally induced bushing made of 6082 aluminum alloy. The drilling parameters were optimized by response surface methodology. The optimum drilling process parameters, which affect the surface roughness values and bushing dimensions, were predicted separately by applying the main effects plot and analysis of variance. There is a good agreement between the experimental results and the presented models. It was found that the optimal parameters for the lowest surface roughness value involve RS of 1250 rpm, FR of 200 mm/min, and β of 45°, while the greatest bush height was obtained at RS of 1250 rpm, FR of 200 mm/min, and β of 50°. Moreover, the microstructure of the regions surrounding the friction-drilled hole showed the existence of fine grains near the drilled edge.
... The pure Al ingots were melted in an induction furnace, reaching a temperature of 900 • C. Superheating the molten Al was targeted to improve its fluidity and wettability while mitigating the surface tension effect [30], allowing the molten Al to smoothly flow into the intricate voids of the lattice 316L SS structure. Prior to pouring in the mold, a degassing process of the molten aluminum was conducted by blowing Argon gas for 30 s in a crucible to diminish gas layers surrounding the molten Al [31], and thus eliminate the formation of pores in the Al-matrix after solidification. Fig. 3 displays schematic drawings of the casting process, illustrating both the horizontal and the vertical fixation of the 316L SS reinforcements in the C-steel die. ...
Friction drilling is a non-conventional hole-making process suitable for thin-section, ductile metals. During friction drilling, heat is generated due to tool rotation and the resulting flow of metal creates a bushing on the exit side of the hole. The bushing offers a longer engagement length for any subsequent thread making process. The threaded holes in this study were created by friction drilling and thread forming in 6082-T6 aluminium alloy. Four scenarios of the threaded holes were created with four levels of rotation rates of friction drilling processes (2000 rpm to 4000 rpm) and the mechanical properties of the threaded holes were compared. It was shown that 3000–3500 rpm is the optimum range of the rotation rate that achieved the higher load-bearing capacities (i.e., resistance to thread stripping) of 5.0–5.5 kN. In addition, the regions close to the thread surfaces in all scenarios were found to have experienced localised hardening to a hardness from 113 HV to around 125 HV.
In this study, the mechanical and microstructural properties of Al-Zn-Mg-Cu-Zr cast alloy with 0.1% Sc under homogeneous, dissolution, and T6 and thermomechanical treatments with the aim of increasing the volume fraction of MgZn2. Al3(Sc,Zr) reinforcing precipitates were examined by hardness, microscopic examinations, tensile tests and software analysis. The results showed that, firstly, the hardness results are well proportional to the results of the tensile properties of alloys and, secondly, the strength of the alloy with thermomechanical treatments compared to T6 treatments increased from 492 MPa to 620 MPa and the elongation increased from 8% to 17% and was 100% upgraded. Microstructural and fracture cross section investigations showed that Al3(Sc,Zr) nanosize dispersoids were evenly distributed among MgZn2 dispersoids and the alloy fracture was of semi-ductile type and nanosize dispersoids less than 10 nm were observed at the end of the dimples in the fracture section. The volume fraction of nanosize dispersoids in the whole microstructure of thermomechanical treatment samples was also much higher than that of T6 heat treated samples, so that the percentage of Al3(Sc,Zr) precipitates arrived from less than 1% in T6 operation to 8.28% in the quench-controlled thermomechanical operation (with 50% deformation). The quality index (QI) in thermomechanical treatment samples is 19% higher than T6 samples, so that this index has increased from 641 in T6 operation to 760 in samples under thermomechanical treatment due to precipitate morphology, volume fraction of precipitates, their uniform distribution in the matrix, and nano sized precipitates in samples under thermomechanical treatment.
Casting aluminum alloys are commonly used in industries due to their excellent comprehensive performance. Alloying/microalloying and post-solidification heat treatments are the most common measures to tune the microstructure for enhancing their mechanical properties. However, it is very challenging to achieve accurate and efficient development of novel casting aluminum alloys using the traditional trial-and-error method. With the rapid development of computer technology, the computational thermodynamics (CT) in the framework of the CALculation of PHAse Diagram approach, the data-driven machine learning (ML) technique, and also their combinations have been proved to be effective approaches for the design of casting aluminum alloys. In this review, the state-of-the-art computational alloy design approaches driven by CT and ML techniques, as well as their combinations, were comprehensively summarized. The current status of the thermodynamic database for aluminum alloys, as the core for CT, was also briefly introduced. After that, a variety of successful case studies on the design of different casting aluminum alloys driven by CT, ML, and their combinations were demonstrated, including common applications, CT-driven design of Sc-additional Al-Si-Mg series casting alloys, and design of Srmodified A356 alloys driven by combing CT and ML. Finally, the conclusions of this review were drawn, and perspectives for boosting the computational design approach driven by combining CT and ML techniques were pointed out.
Friction drill joining is a one-sided thermo-mechanical joining process to connect similar and dissimilar materials. Due to the excellent potential for multi-material joining and wide application in designing the lightweight and modern vehicle, special attention has been paid to this approach of the friction drilling process. However, the most challenging issue in this process is the joint quality. This paper focuses on the effect of process parameters on joint quality and tool performance. A modification method to improve the joint quality is also provided. The quality of the formed joint is analysed, by applying the tensile shear test. Moreover, the microstructural alteration of the formed joint is characterized. The main contribution of this work is presenting a new approach of friction drilling for the joining of sheet metals. The findings reveal that optimum process parameters, in terms of maximum joint quality and tool performance, are spindle speed 3000 rpm and feed rate 120 mm/min. It is found that the hardness near the formed hole is greater than the base material. The findings also contribute to providing an enhanced microstructural characterization of sheets, which identifies the material behaviour and shows how it affects the joint quality.
Friction drilling is a widely used process to produce bushings in sheet materials, which are processed further by thread forming to create a connection port. Previous studies focused on the process parameters and did not pay detailed attention to the material flow of the bushing. In order to describe the material behaviour during a friction drilling process realistically, a detailed material characterisation was carried out. Temperature, strain rate, and rolling direction dependent tensile tests were performed. The results were used to parametrise the Johnson–Cook hardening and failure model. With the material data, numerical models of the friction drilling were created using the finite element method in 3D as well as 2D, and the finite volume method in 3D. Furthermore, friction drilling tests were carried out and analysed. The experimental results were compared with the numerical findings to evaluate which modelling method could describe the friction drilling process best. Highest imaging quality to reality was shown by the finite volume method in comparison to the experiments regarding the material flow and the geometry of the bushing.
The thickness of sheet metal parts can be locally increased by friction drilling technology via forming of a hole with a bush by a special drilling tool. Here, a 7075 Al-alloy was drilled by friction using tool cone angles with values of 40, 45 and 50° under different feed rates (100, 200 and 315 mm/min) and rotational speeds (1000, 1250 and 1600 rpm). The present study investigates the hardness distribution in the thermally-formed bush and in the heat-affected zone around the bush. It was found that the hardness of the bush was slightly increased with increasing of the tool cone angle and reduction of the tool rotational speed. However, the hardness of the thermally-induced bush showed values lower than the parent metal. The hardness near the drilling surface was approximately 65±10 HV, while it recorded hardness values of 75±10 HV at 5 mm away from the drilling surface. In addition, the microstructure of the friction drilled specimens showed a very fine structure in the drilling zone due to crushing of the original structure during the friction drilling process.
Friction drilling is one of the most promising methods for hole making in thin sheets of conventional structural alloy materials (aluminum, steel, copper, titanium, etc.) and novel polymer composites. Despite almost a hundred year history of studying friction drilling, it is still highly relevant and is actively developed. The aim of the present review is to cover as fully as possible all aspects of this technology. The paper analyzes the advantages and disadvantages of friction drilling, discusses the influence of technological parameters on the drilled hole quality. The technological parameters considered are not only the feed rate and spindle speed, but also the tool configuration. The quality of the holes refers to their strength, inner surface hardness, hole geometry and roughness, bushing geometry, and so on; therefore, they are also analyzed. From a fundamental point of view, frictional drilling is interesting in that it causes structural changes in the material as a result of severe plastic deformation, which is discussed in a separate section. Approaches for the process modeling are considered which quite accurately predict the material behavior. A technically more advanced technology of a new generation is discussed, namely flow drill screwdriving. A general conclusion is that despite the widespread use of friction drilling, including by well-known engineering companies, the technology continues to develop with regard to the changing needs of the industry and the market and strengthens its position in the industry.
https://authors.elsevier.com/a/1cnHa5R78j1YDT
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This study investigates the friction drilling behaviors of AA7075-T6 aluminum and AZ31B magnesium alloys containing ceramic powders of B4C, SiC, and Al2O3 under dry and minimum quantity lubrication (MQL). The aim is to create a composite structure while applying the pressure of a drilling tool on the hole surface when adding ceramic powders into the cutting oil during frictional drilling. Friction drilling tests are performed at a constant spindle speed and feed speed, and the effects of dry and cutting oil mixtures containing ceramic particulates on the thrust force, temperature, hole surface quality, bushing profile, and thread stripping strength of the specimens are investigated. The results revealed that ceramic particles penetrated through the hole and created a composite structure on the surface. The dry friction drilling of AA7075-T6 and AZ31B yielded acceptable surface quality. However, the surface quality worsened considerably during the friction drilling of AA7075-T6 using the oil mixture, whereas the surface roughness and hole bushing of AZ31B magnesium alloys are not negatively affected by the ceramic containing oil mixtures. Petal formation and cracks appeared in the hole profiles of the AA7075-T6 aluminum alloy. Thread stripping tests indicate that the ceramic-particle- containing oil mixtures enhanced the thread shear strength of AA7075-T6 by 19.2 %, and the highest shear strength of 56.78 kN is achieved using the Al2O3 containing an oil mixture. The oil mixture-containing B4C ceramic particles improved the thread shear strength of AZ31B by 7.7 %.
Aluminum‐silicon alloys have been widely used in automotive industries. To know mechanical properties of such materials is essential for engineers to have a superior design for components. Therefore, in this article, the sensitivity analysis of mechanical and fracture features in the aluminum alloy has been performed to find the effect of the loading rate and nano‐particles. For this objective, tensile tests were performed on casting standard specimens. Then, obtained experimental data were analyzed by the Minitab software, using the factorial method. In addition, the interaction between the effect of the loading rate and the addition of nano‐particles, on mechanical properties and ductile/brittle behaviors, was also investigated. Obtained results indicated that the yield stress, the elastic modulus and the elongation were sensitive to the interaction of both factors (the multiply of the nano‐particle addition and the loading rate). Besides, the fracture surface illustrated that by increasing the loading rate and the addition of nano‐particles, the brittleness of the material increased.
AlSi10Mg manufactured by laser powder bed fusion (or selective laser melting) benefits from a very fine microstructure that imparts significant mechanical strength to the material compared to the cast alloy. The build platform temperature stands out as a significant processing parameter influencing the microstructure as it affects the cooling rate and thermal gradient during manufacturing. Setting the build platform temperature to 200°C yields a negligible residual stress level. However, the strength is lower compared to that obtained using a build platform temperature of 35°C, with a similar fracture strain. A detailed 3D microstructural analysis involving focused ion beam/scanning electron microscopy tomography was performed to describe the connectivity and size of the Si-rich eutectic network and link it to the strength and fracture strain. The coarser microstructure of the 200°C build platform material is more prone to damage. The α-Al cells as well as the Si-rich precipitates present a larger size in the 200°C material, the latter thus having a lower strengthening effect. The Si-rich eutectic network is also less interconnected and has a larger thickness in the 200°C material. An analytical model is developed to exploit these microstructural features and predict the strength of the two materials.
Friction drilling is a nontraditional hole making process getting tremendous attention recently. In this process, tool is penetrated into the work piece due to the softening caused by the heat, which is developed between tool and the work piece. Materials less than 5mm thickness can be used for friction drilling. Wide varieties of materials such as tool steel, high speed steel, tungsten carbide and H13 steel can be used either with conical profile as friction drilling tool. For improving tool life nano-coating can be applied. This review mainly focuses on various optimization techniques such as Taguchi method and design of experiments, which can be utilized in friction drilling. Surface roughness, conicity and tribological response are also addressed in this study. Various parameters like cutting feed and speed, which play prominent role during friction drilling process are suitably dealt with.
Tool condition plays an important role in machining performance. In machining processes, multiple phenomenon occurs during material cutting. To improve their robustness, the reliability pattern recognition techniques have been implemented in tool condition monitoring systems. This study demonstrates a tool condition monitoring approach in a friction drilling operation based on the vibration signal collected through accelerometer sensors. The experiment has been carried out on a CNC milling machine. In this present work, an optimal parameter in friction drilling has been used on medium carbon steel AISI 1045. The signals were collected by accelerometer sensors and Low-pass-filter was utilized to filter the raw data. Pattern recognition was identified and categorized into one of three clusters which are; tool at good, half-life and worn-out conditions. The results found that the vibration amplitude is directly proportional to tool wear and friction which support the nature of tool wear in drilling process. The hole size reduction on the workpiece can also be seen clearly with the increasing vibration on the process due to the tool wear. With the effectiveness of pattern recognition, the damages of the machine tool can be avoided to control the product quality consistently.
The effect of Si addition on the microstructure and mechanical properties of Al-Mg-Si-Zn aluminum alloys were investigated. Results show that the microstructure of Al-Mg-Si-Zn alloy with low Si contents is mainly composed of Mg2Si and Mg5Si6 phases. With the increasing of Si content, Si and Al3.21Si0.47 phases precipitate in the form of eutectic phases in the alloys, at the same time, the mean shape factor of the second phase firstly increases and then decreases. Regression analysis results show that the Si content has the main influence and the mean shape factor has the least influence on tensile strength. Tensile strength increases significantly with the addition of Si, however, there is a remarkable drop in the elongation of the alloys. Decreased elongation is related to the formation of monotonous Al (200) structure and the enlargement of interplanar spacing of (111) and (200) crystalline planes.
Friction drilling is used to process special holes with a bushing and a boss in thin sheet metals without producing chips via a non-traditional tool-drill. Friction drilling parameters involve the feed rate, rotational speed and profile dimensions of the drilling tool, which directly affect the induced bushings dimensions, as well as, the microstructure of the produced hole. In the present study, friction drilling parameters were manipulated during the performance of friction drilling of 6082 and 7075 Al-alloys, moreover, the temperature variation in the tool-work-piece interface was recorded during the drilling processes via an infrared camera and four thermocouples located at different positions near the drilling zone. During the formation of the bushing and the boss in the investigated aluminum sheet metals, the minimum measured temperature was 220 °C and the maximum measured temperature was 380 °C. It was found that the temperature in the tool-work-piece interface increased with the reduction of the feed rates and the increase of both of the rotating speeds and the tool cone angles. Furthermore, the surface roughness values of the drilled holes were found to be increased with the increase of the rotational speeds.
Thrust force and torque applying in friction drilling contain some important information related to sufficient heat generation which can improve product quality and reduce tool wear. This concern becomes more challengeable when friction drilling is applied on difficult-to-machine materials. In the present study, temperature, thrust force, and torque for friction drilling of difficult-to-machine materials namely AISI304 and Ti-6Al-4V and Inconel718 are measured and analyzed. It contributes to provide an enhanced understanding of how friction in workpiece-tool interface increases the temperature. Subsequently, the sufficient heat generation, the effective thrust force, and torque that are needed to form a proper bushing with optimum features can be predicted. It is found that increasing in number of drilled holes reduces the quality of bushing shape. It is observed that thermal conductivity of workpiece material has significant effect on bushing formation quality. The findings indicate that better bushing formation and longer tool life are obtained from friction drilling of Inconel718. The microstructural changes of workpiece and tool wear are also analyzed and a relationship between them, temperature, thrust force, and torque, is explored. The maximum tool wear is observed on conical region where the process is in critical cycle time and temperature is on peak point.
The main purpose of this research paper is to study experimentally the effects of the thermal friction drilling process parameters such as the tool geometry, feed rate, and rotational speed, on the resultant bushing length, axial and radial forces, hole dimensional error, and roundness error, while drilling AISI 304 stainless steel sheets with different thicknesses using tungsten carbide tools. The experiments were conducted based on the design of experiments method. A test rig was manufactured at Showman Company ‒ Egypt to perform the experimental work, and the tools were offered by Flow drill Company ‒ Netherlands. Also Fuzzy Logic technique is applied to the obtained results to find the optimal drilling condition.
Friction drilling is a non-traditional drilling process, in which specimens are drilled by means of frictional heat, which is
obtained from friction effect in between rotating conical tool and workpiece area. The main purpose of current study was to
investigate the effect of pre-drilling depth and diameter on the bushing shape, initial deformation and frictional heat in
friction drilling of A7075-T651 aluminum alloy, known as a brittle material. Results showed that the effect of pre-drilling
depended on the geometrical dimensions of the tip of the tool. The initial deformation was reduced, frictional heat was
generated regularly and bushing shape was in the form of cylindrical with less cracks and petal formation in conditions predrilling
diameter close to the end diameter of the tip of the tool and pre-drilling depths bigger than its length. The highest
temperature was recorded at 3000 rpm spindle speed and 40 mm/min feed rate.
The present work was carried out on Al-7%Si-0.4%Mg-X alloy (where X = Mg, Fe, Sr or Be), where the effect of solidification rate on the eutectic silicon characteristics was investigated. Two solidification rates corresponding to dendrite arm spacings (DAS) of 24 and 65 μm were employed. Samples with 24 μm DAS were solution heat-treated at 540 °C for 5 and 12 h prior to quenching in warm water at 65 °C. Eutectic Si particle charateristics were measured using an image analyzer. The results show that the addition of 0.05% Be leads to partial modification of the Si particles. Full modification was only obtained when Sr was added in an amount of 150-200 ppm, depending on the applied solidification rate. Increasing the amount of Mg to 0.8% in Sr-modified alloys leads to a reduction in the effectiveness of Sr as the main modifier. Similar observations were made when the Fe content was increased in Be-treated alloys due to the Be-Fe interaction. Over-modification results in the precipitation of hard Sr-rich particles, mainly Al4SrSi2, whereas overheating causes incipient melting of the Al-Cu eutectic and hence the surrounding matrix. Both factors lead to a deterioration in the alloy mechanical properties. Furthermore, the presence of long, acicular Si particles accelerates the occurrence of fracture and, as a result, yields poor ductility. In low iron (less than 0.1 wt%) Al-Si-Mg alloys, the mechanical properties in the as cast, as well as heat treated conditions, are mainly controlled by the eutectic Si charatersitics. Increasing the iron content and, hence, the volume fraction of Fe-based intermetallics leads to a complex fracture mode.
Friction drilling is a non-traditional hole achieving method that is a clean, chip-less process, which is called thermal drilling, form drilling, flow drilling, and friction stir drilling. In this study pre-drilling friction drilling was investigated for improving the bushing shape of A7075-T651, which is a brittle cast material. During the process, surface roughness and bushing shapes were analyzed and generated frictional heat was measured by the virtue of thermocouples. Experiments were carried out to 4 mm and 6 mm in thicknesses of A7075-T651 aluminum alloy at 1200, 1800, 2400, 3000, and 3600 rpm spindle speeds, 20, 40, 60, 80, and 100 mm/min feed rates with using high-speed steel rotating conical tool, whose diameter is 8 mm. Consequently, the bushing shapes were advanced without cracks and petal formation in pre-drilling Friction drilling in comparison with without pre-drilling process. With increasing pre-drilled hole diameter the generated frictional heat was decreased. The achieved temperature was realized to be 1/2–1/3 of the melting temperature of the workpiece. Surface roughness values were decreased with decreasing or increasing both spindle speed and feed rate correspondingly.
Friction drilling is a hole-making process suitable for thin sections of ductile metal. A rotating tool is plunged into the workpiece to form the pilot hole. The hole is then threaded in a follow-up process. A bushing forms on the exit side of the hole, which allows for longer engagement lengths in threaded assemblies. For comparison purposes, four combinations of threaded-hole processes were applied to 1.5 mm-section, 6082-T6 aluminium alloy. The processes involved were friction and twist drilling followed by thread forming or cutting. Vickers hardness and microstructural analyses were used to assess the condition of the material. An in-house test method was developed to measure the axial load–deflection response. Progressive failure occurred by thread stripping. Friction drilling followed by thread forming gave peak loads 35% higher than conventionally drilled and tapped holes. Also, hardness increased from 111HV in the parent metal to 125HV (with an increase in hardness to depths of 0.5 mm) due to work hardening. Evidence of precipitate dissolution was negligible which suggests that the friction drilling process operated below the solvus temperature. A novel approach for determining reliably-based, thread-stripping Factors of Safety (FoS) is presented. FoS in the range 3.61 to 4.38 gave a reliability of 95% to 99.9% against thread stripping in friction-drilled, thread formed joints.
As a non-conventional drilling process, friction drilling has been successfully used for sheet metal hole-making, increasing the effectiveness of thread length, and screw coupling. The main challenges and obstacles to the implementation of the friction drilling process for difficult-to-machine materials are excessive tool wear and inadequate product quality. This study aims to investigate the effect of the two most significant parameters namely spindle speed and feed rate on bushing formation quality and drilling tool performance, and determination of optimal process parameters experimentally and numerically, both. Firstly, by using the full factorial method the experiments are designed. Then, the collected experimental data are statistically evaluated by analysis of variance (ANOVA) using the MINITAB tool. The findings reveal that spindle speed is a more significant parameter than feed rate that intensively affects machining and drilling tool performance. Moreover, the resultant optimum parameters combination for AISI304 is spindle speed 1000 rpm and feed rate 105 mm/min, for Ti-6Al-4 V is spindle speed 1000 rpm and feed rate 145 mm/min, and for Inconel718 is spindle speed 1500 rpm and feed rate 145 mm/min. Above all else, because of the good creep-rupture resistance of Inconel718, this material presents a great reaction concerning the high quality of formed-bush and drilling tool performance. Contrariwise, the low thermal conductivity of Ti6Al-4 V causes insufficient heat transfer throughout the workpiece, poor product quality, and severe tool wear. On the other hand, the effects of feed rate and spindle speed on the distribution of thermal stress and heat generation on workpieces are studied numerically. This proves the great potential of finite element analysis for an optimization study.
In the present research, an attempt was made to determine the suitable coated tool for drilling AA5052 nano hybrid sandwich sheet using Response Surface Methodology (RSM) and Taguchi method. The work aims at minimizing thrust force and torque on a friction drilling tool for drilling holes. Plasma Nitriding, Liquid Nitriding, and PVD Titanium Nitride (TiN) coating are applied on H13 steel tool material. Results indicate that for achieving minimum torque and thrust force, feed of 50 mm/rev and spindle speed of 4000 rpm to be used during drilling. Whereas, to reduce the drilling time, feed has to be increased up to 200 mm/rev. The maximum bushing height is 5.6 mm for Liquid Nitrided tool at 2500 rpm, 50 mm/rev, and 5.4 mm for PVD TiN-coated tool at 3000 rpm, 200 mm/rev, whereas 4.71 mm is the minimum bushing height for Plasma Nitrided tool at 3500 rpm, 150 mm/rev. The result obtained from RSM was compared with Minitab response optimizer and Harmonic Search Algorithm. PVD TiN coated tool exhibited the best performance in terms of low thrust force value of 84.70 N at 4000 rpm, 50 mm/rev and low torque value of 1.5395 N-m at 2500 rpm, 50 mm/rev.
Cast aluminum alloy A380 is one of the most commonly specified alloys that has light weight and exhibits excellent resistance to hot cracking, which makes it necessary in many industrial applications. An idea is investigated to generate a cylindrical bushing without significant petal formation and radial fracture that are expected to be obtained by friction drilling of cast metals. Three materials; namely, 316 stainless steel, Al6060 aluminum alloy, and red copper alloy are used in which each of them is located on the upper and lower surfaces of A380 workpiece, so achieving the idea of the functionally graded material. The process parameters were studied for reducing the resultant axial force, the gap between surfaces, and achieving a longer bushing without petal formation and radial fracture. Lower feed rate achieves minimum axial force and gap thickness with maximum bushing length for all material sandwiches. An optimized decision making by the help of fuzzy logic techniques is performed, revealing that red copper sandwich exhibits the optimal multiple performance characteristic index based on axial force, bushing length, gap thickness, and gap divergence.
In this study modification of AA2024 microstructure produced by friction drilling was investigated. To reveal the role of deformation, high temperature and friction on microstructure modification methods of optical and scanning electron microscopy and microhardness test were used. Different zones of material around friction drilling hole has a special characterization through grain size, volume fraction and size of incoherent second phase particles and microhardness. It has been found that deformation, high temperature and friction in friction drilling process lead to recrystallization of grain structure and dissolution of incoherent second phase particles due to strain-induced dissolution effect. Microhardness of recrystallized material has increased.
Optimum laser irradiation conditions to achieve dense A356.0 (AlSi7Mg0.3) specimens fabricated by selective laser melting (SLM) were studied. The SLM specimens with relative density of 99.8% were obtained. The microstructures and mechanical properties of the dense SLM specimens fabricated under the optimum laser irradiation conditions were also investigated. The dense SLM specimens had an ultimate tensile strength, yield strength, and breaking elongation of 400. MPa, 200. MPa, and 12-17%, respectively. All of these values considerably exceeded those in cast-melting materials. The superior mechanical properties of the SLM specimens could be attributed to fine dendritic cell microstructures and relative density of almost 100%. An investigation of the heat treatment effects on the microstructures and mechanical properties revealed a clear difference in annealing behaviors between the SLM specimens and the cast-melting materials. After annealing (T5), the breaking elongation of the SLM specimen increased from 15% in the as-fabricated specimen to 30% in the specimen annealed at 350. °C, while the ultimate tensile strength and yield strength decreased from 400. MPa and 250. MPa to 200. MPa and 125. MPa, respectively. This confirmed that the mechanical properties of the SLM specimens could be controlled in accordance with required functions for design.
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Standard practice for micro-etching metals and alloys
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Investigate the surface roughness and bushing shape in friction drilling of A7075–T651 and st 37 steel
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Evaluation of tool wear and machining performance by analyzing vibration signal in friction drilling
- Abdul Mutalib
Metallurgical parameters controlling the eutectic silicon charateristics in be-treated Al-si-mg alloys
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An experimental investigation of the effect of depth and diameter of pre-drilling on friction drilling of A7075–T651
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