Search

Friction stir welding (FSW) has been widely used in welding of metal. However, it is difficult to weld high melting point metal by FSW because of short life or high price of FSW tools. Silicon nitride tool can have both long life and low cost. Although the silicon nitride tool, which has high temperature mechanical properties, could have a long tool life for FSW of steel, it is not clear how FSW conditions affected the tool life. In this study, changes in the shape of the FSW tool was focused. A comparative verification of the tool shape changes due to the FSW conditions was carried out, and specific shape changes in silicon nitride tools were verified. The silicon nitride tool was worn only at the shoulder and not at the probe. Furthermore, the wear shape was different depending on rotation speed and welding speed of the tool. The factors that cause them were analyzed using temperature and stress simulations for silicon nitride tools. Increasing the rotation speed broadened temperature distribution, increased the peak temperature and narrowed the stress distribution. When the welding speed was increased, the temperature distribution became narrower and peak temperature was lower, and the thermal asymmetry increased, while the stress distribution expanded and the stress asymmetry increased. When the welding speed was high, the agitation in the plastic flow zone was insufficient, and there were places where the stress and temperature were low around the shoulder. It is considered that these decrements of the stress and temperature lead to the concave part remaining on the outer circumference. Therefore, it is important to control both the welding speed and the rotation speed of the silicon nitride tool in order to suppress the protrusion which is main reason of the tool breakage. [ABSTRACT FROM AUTHOR]

The study aims to fill the gap in the existing literature by investigating the effects of various tool materials, including copper, tungsten carbide, and brass, on performance parameters in electric discharge machining (EDM) simulations. The authors developed a modified gaussian heat flux equation that incorporates the electrical resistivity of both the tool and workpiece, based on prior experimental investigations. The authors further developed a finite element model that incorporates the modified Gaussian heat flux equation, spark radius, and fraction of heat transferred to workpiece as a function of pulse on time and pulse current, latent heat, specific heat values, and thermal conductivity properties. The outcomes of the simulation indicated that the Cu tool exhibited the minimum MRR and SR values when subjected to a current of 9 amps and a duty cycle of 0.4, as well as a current of 12 amps and a duty cycle of 0.6. The results also indicate that the brass tool displayed marginally elevated MRR and SR, whereas the Tungsten carbide tool exhibited the highest MRR and SR. The simulation results for all three tool materials showed similar trends, consistent with prior research. Also, an increase in gap voltage, pulse current and duty cycle was observed to correspond with increased MRR and SR. Authors also observed that as electrode material electrical conductivity increased, so did workpiece material residual stresses. These results assist with the choice of tool materials for EDM processes, allowing for finer control over performance parameters and greater machining efficiency. [ABSTRACT FROM AUTHOR]

In this paper, experimental analysis was performed during micro-electrical discharge machining (micro-EDM) of titanium alloy Ti–6Al–4V (grade 5) using three types of tools viz. copper (Cu) tool, tungsten carbide (WC) tool, and synthetic graphite (Gr) grade three tool. The main process parameters were taken as (a) pulse on time ( T on ), (b) pulse off time ( T off ), (c) voltage (V), and (d) capacitance (C). The output responses were taken as the material removal rate (MRR) and tool wear rate (TWR). Taguchi method coupled with grey relational analysis (GRA) (L 1 6 orthogonal array) technique was applied to optimize the input process parameters for both the responses. Scanning electron microscopy (SEM) analysis of the workpiece and tool was also performed to investigate the morphology of the machined surface and tool surface. Energy-dispersive spectroscopy (EDS) analysis was performed to investigate the elemental composition of the machined surface. The experimental finding reveals that tungsten carbide is the most suitable tool material for machining the chosen workpiece for obtaining optimal MRR and TWR. The optimum condition for the copper tool was found as 180 V, 1000 pf, 10 μ s ( T on ), and 10 μ s ( T off ). Meanwhile, the optimum parametric condition for tungsten carbide and graphite tools was found to be the same as 240 V, 100 pf, 20 μ s ( T on ), and 5 μ s ( T off ). [ABSTRACT FROM AUTHOR]

Joining high strength 2xxx series aluminum is known to be complex and difficult; these alloys are traditionally considered non-weldable for fusion welding. This paper describes details on welding AA2029-T8 for skin-stiffened structures using refill friction stir spot welding (RFSSW). RFSSW is a solid-state process invented in the early 2000s that produces spot welds that are strong, lightweight, flush, and hermetic. Cycle times between 1 and 3 s are discussed, and process forces within a range of 8 to 14 kN are demonstrated. Furthermore, lap-shear quasi-static tensile strengths are shown to be between 10 kN and 12 kN in 9 mm diameter spots. A comparison of the performance of RFSSW welds made with various tool materials—which include H13 tool steel, tungsten carbide, and MP159—is detailed. Comparisons of parameters, weld consolidation, and heat-affected zones are presented with discussion related to heat generation specific to each tool material. [ABSTRACT FROM AUTHOR]

Joining high strength 2xxx series aluminum is known to be complex and difficult; these alloys are traditionally considered non-weldable for fusion welding. This paper describes details on welding AA2029-T8 for skin-stiffened structures using refill friction stir spot welding (RFSSW). RFSSW is a solid-state process invented in the early 2000s that produces spot welds that are strong, lightweight, flush, and hermetic. Cycle times between 1 and 3 s are discussed, and process forces within a range of 8 to 14 kN are demonstrated. Furthermore, lap-shear quasi-static tensile strengths are shown to be between 10 kN and 12 kN in 9 mm diameter spots. A comparison of the performance of RFSSW welds made with various tool materials—which include H13 tool steel, tungsten carbide, and MP159—is detailed. Comparisons of parameters, weld consolidation, and heat-affected zones are presented with discussion related to heat generation specific to each tool material.

Friction stir welding (FSW) has been widely used in the welding of low melting point metal, such as Al alloy or Cu alloy. However, high melting point metal, such as Fe alloy, it is difficult to be welded by FSW because of short life or the high price of FSW tools. Silicon nitride tool can have both long life and low cost. In order to obtain design guideline for silicon nitride FSW tool, the relationship between the mechanical properties and tool life was examined. Two silicon nitride materials which had different microstructure were prepared. One of them had lower high-temperature mechanical properties and the other had higher properties. Tools made by them could join the SUS 304 plate under the following conditions; welding speed was lower than 1000 mm/min, and revolutional pitch was lower than 1.8 mm/r. Even the tool which had excellent mechanical properties at high temperature worn faster when the joining temperature was 950 °C or higher. The tool with excellent high-temperature mechanical properties had a tool life 6 times longer than the other tool. It is considered the life of the tool was improved when the crystallization of the grain boundary phase promoted the rise in the melting point of the grain boundary phase and the precipitation of silicon oxide during FSW. [ABSTRACT FROM AUTHOR]

α/β‐SiAlON/SiC composite ceramic tool materials were prepared via spark plasma sintering. The effects of content and size of SiC particles and sintering temperature on phase composition, mechanical properties, and microstructure were investigated. The results indicated that SiC restrained the transformation of β‐SiAlON to α‐SiAlON, but higher SiC content (≥10 wt.%) resulted in a higher Vickers hardness of the composite. The large size of SiC particles raised the densification temperature of α/β‐SiAlON composites, and small SiC particles benefited to improve microstructure. There were more equiaxed α‐SiAlON grains and β‐SiAlON with a larger aspect ratio (α¯95$\bar{\alpha}_{95}$ = 5.1) in the α/β‐SiAlON composite containing 100 nm SiC. The sample containing 10 wt.% 100 nm SiC particles sintered at 1700°C had the optimal properties with a Vickers hardness and fracture toughness of 18.5 ±.2 GPa, 6.4 ±.2 MPa m1/2, respectively. [ABSTRACT FROM AUTHOR]

Influence of the rotational speed can be clearly seen by using field-emission scanning electron microscopy (FE-SEM). The influence of rotating speed on macro and microstructures, hardness, shear performance and failure mechanism of friction stir welding on AA7075-T6 Al alloy with a thickness of 5 mm was investigated. At the lowest rotational speed, the data show a significantly closer hardness distribution in the AA7075-T6 Al alloy plates used during the friction stir welding process. The presence of the Fe- compounds was observed in the fracture surface of the nugget zone through the microstructure analysis. In this experimental investigation H-13 steel tool is used for friction stir welding process. [ABSTRACT FROM AUTHOR]

Hybrid laminates made of Carbon Fibre and Glass Fibre Reinforcement have become widely popular in various applications which are mainly due to their excellent structural strength coupled with lower cost. In all these applications, drilling plays a crucial role during the assembly of these structural components. This paper deals with the examination of the influencing parameters (feed rate, tool material) on thrust force during drilling of hybrid laminates. Statistical Design of Experiments has been used for the analysis of the drilling parameters on the thrust force. Taguchi's L9 (32) array has been used to determine whether the response function is minimised by feed rate or tool material. Hole drilling on hybrid FRP laminate has been done using Solid Tungsten Carbide and High-Speed Steel tool material under controlled machining operations. The results reveal that the tool material has a higher influential effect on the thrust force when compared with the feed rate. Also, the morphology of hybrid laminate was obtained using a Scanning Electron Microscope (SEM) and the results indicate that surface texture was observed to be optimum. [ABSTRACT FROM AUTHOR]

Friction that occurs in metal forming processes is significantly different from the friction in mechanical joints. Specific pressures in deep drawing with thinning of the wall thickness that occur on the contact surface between the deformed metal and the tool are very high and considerably exceed the yield stress of the workpiece. As a result of such high pressures there are significant changes in the friction conditions, the efficiency of the lubrication is reduced (the lubricant layer breaks and a direct contact of the surfaces occurs) and the wear process is intensified. This paper shows the analysis of the influence of different process parameters (the die angle, lubrication on die and punch, the punch surface roughness, tool material, etc.) on the mean contact pressure based on performed experimental tests on the model.

A novel ceramic coating-like (CCL) structure was proposed for preparing a potential ceramic cutting tool material. The influence of critical factors, including the material composition, composition content and surface layer thickness, on the residual stress was analyzed by the finite element method (FEM). Under the condition of the optimized parameters, the compressive stress generated on the surface layer of the CCL tool material ranged from −163 MPa to −248 MPa. Based on the obtained results, a (Ti,W)C/Al 2 O 3 +SiC CCL tool material was prepared by vacuum hot-pressing sintering, indicating the residual compressive stress (−122.3 MPa) of the surface layer. Compared with the performance of homogeneous cermet materials, the surface hardness and flexural strength of the CCL tool materials were increased by 46.58% and 37.76%, respectively. Moreover, the SEM imaging results of the sample surface and fracture morphology and the energy dispersive spectroscopy (EDS) analysis results showed that the dense ceramic surface and phase interfacial transition layer were formed with a uniform gradient distribution and without defects. [ABSTRACT FROM AUTHOR]

The use of the multi-spindle head in drilling technology can reduce the drilling cycle time by simultaneously producing multiple holes in one go. However, selecting the appropriate drill material and geometry is critical to overcoming the challenges of multi-hole drilling to ensure high-quality holes. This study investigates the use of the multi-spindle head with different tool configuration, tool materials and tool geometry during multi-hole simultaneous drilling of Al2024. A comparison is made among the high-speed steel drills (diameter: 6 mm; point angle: 118°) and two different carbide drills (diameter: 6 mm and 10 mm; point angle: 140°) as well as the maximum and minimum possible centre to centre tool distances of the multi-spindle head. The experiments are based on measuring the thrust force, evaluating the hole quality in terms of surface roughness and burrs, the formation of chips and post-drilling tool conditions. The results showed that carbide drills with high point angle and smaller diameter generated less thrust force, produced higher quality holes, and formed less built-up edge due to short chips. Besides, tools of the multi-spindle head can be adjusted in any position without affecting the hole quality which is useful for increasing productivity at a higher rate in manufacturing industries. [ABSTRACT FROM AUTHOR]

In this paper, a state-of-the-art review on cutting tool technology in machining of Ni-based superalloys is presented to better understand the current status and to identify future directions of research and development of cutting tool technologies. First, past review articles related to the machining of Ni-based superalloys are summarized. Then machinability of superalloys is introduced, together with the reported methods used in cutting tool design. The current researches on cutting tools in the machining of superalloys are presented in different categories in terms of tool materials, i.e., carbide, ceramics, and Polycrystalline cubic boron nitride (PCBN). Moreover, a set of research issues are identified and highlighted to improve the machining of superalloys. Finally, discussions on the future development are presented, in the areas of new materials/geometries, functional surfaces on the cutting tool, and data-driven comprehensive optimization. [ABSTRACT FROM AUTHOR]

This research conducts in three sections. The first section studies the effect of tool materials and gases on rotary workpiece electrical discharge machining. During the experiments, the effects of three kinds of tool materials (Cu, Cu-Cr, and Cu-Sn) and three types of industrial gases (air, argon, and CO2) on the material removal rate, tool wear rate, and workpiece surface roughness are investigated. The second is a comparison between rotary workpiece, rotary tool, and the fixed workpiece by choosing the appropriate tool material and gas in order to observe the effect of workpieces rotation on the process. Finally, another comparison has been done between wet electrical discharge machining and near dry electrical discharge machining of the fixed workpiece in order to study the effect of the dielectric. The results show the copper tool has the best performance compared with other tools. Scanning electron microscopy output shows the Cu-Sn tool creates shallow micro-cracks on the surface. Air and CO2 gases have the higher material removal rate in low current, but argon has better function than other gases in high current. In addition, a rotational speed causes an increase in material removal rate and tool wear rate and surface roughness decrease in near dry electrical discharge machining. The level of tool wear rate has decreased by 14% in the rotary workpiece compared with the rotary tool. [ABSTRACT FROM AUTHOR]

Cutting tool material has a significant effect on the temperature of the tool during machining that determines the tool life and machining performance. The objective of this study is to analyze the effect of reducing the grain size of tool material on tool life and cutting performance in terms of tool temperature and cutting forces during ball end milling of tool steel AISI H13. Tool material was prepared from three different sizes of tungsten carbide (WC) powder mixed with cobalt binder and sintered to fabricate ball end mills. The thermo-mechanical properties of the tool material were determined to investigate the effect of grain size. Machining tests were conducted to evaluate the performance of the tool in terms of tool temperature, cutting forces, and tool wear. Results showing a decrease in tooltip temperature with the reduction in grain size of the tool are the main and novel findings of this paper. The same trend was followed in the case of cutting forces and wear. [ABSTRACT FROM AUTHOR]

This paper presents the results of experimental studies on the process of thermal drilling in workpieces made of barely deformed alloys by the example of the alloy HN62VMYuT-VD. A comparative analysis is presented, and the modes efficient from the standpoint of thermal drill wear and the process productivity are demonstrated. In addition, the revealed geometrical parameters and material of the tool required for the implementation of the thermal drilling operation are presented. The results of simulation with the use of the QForm VX software package are shown in comparison with the experimental results obtained. [ABSTRACT FROM AUTHOR]

The production of WC–Co alloy by spark plasma sintering under pressure is proposed. The influence of the sintering conditions on the structure and mechanical properties of the alloy is investigated. We show that the composites obtained by spark plasma sintering have better mechanical properties than those produced by traditional hot pressing. [ABSTRACT FROM AUTHOR]

A verification experiment was performed to monitor the impact of technical, technological, material, and tool factors on the roughness of the milled surface (average roughness Ra) during plane milling of thermally treated spruce wood. The technological parameters were: four heat treatment temperatures (160 °C, 180 °C, 200 °C, and 220 °C; one sample kept in its natural state), three feed rates (6 m·min-1, 10 m·min-1, and 15 m·min-1), three cutting speeds (20 m·s-1, 40 m·s-1, and 60 m·s-1), three tool rake angles (15°, 20°, and 30°), and three types of used blades (HSS 18% W with AlTiCrN coating, tool steel knife 19 573 induction hardened, and steel knife MAXIMUM SPECIAL 55). The result of the experiments showed the individual effects of the parameters in the following order: used knife, heat treatment, angular geometry, cutting speed, and feed rate. [ABSTRACT FROM AUTHOR]

WC-Co cemented carbides, with low binder content (Co content <4 wt.%), have become prospects as ultra-precision cutting tool materials as a result of their high hardness, which can be ground to a sharp cutting edge when machining tools. In this paper, three cemented carbides, with Co content of 1 wt.%, 2 wt.% and 3 wt.%, were systematically investigated. The mode of preparation, properties, microstructure and ultra-precision turning of these cemented carbides were studied. It has been researched that 0.1 wt.% VC could effectively refine the WC grains to exhibit excellent properties. The optimum sintering temperatures for WC-1Co-VC, WC-2Co-VC and WC-3Co-VC were 1350, 1300 and 1300 °C, respectively. The resultant cemented carbides displayed extremely high hardness (2450, 2377 and 2325 kg/mm2), high relative density (>99%), specific fracture toughness (8.89, 9.01 and 10.17 MPa·m1/2) and transverse rupture strength (1274, 1387 and 1474 MPa). During oxidation, from room temperature to 400 °C, there was a slight reduction in the strength of the cemented carbides with no oxide formed. From 400 to 600 °C, their strength decreased significantly with apparent oxides formed on the surface. At 800 °C, all the cemented carbides experienced a severe drop in strength and massive oxidation on the surface and fracture surface. The cemented carbides were used to make cutting tools used for ultra-precision turning of brass. The surface roughness after machining with the three modified cemented carbide tools, with increasing Co content, were 22, 14 and 17 nm, respectively. [Display omitted] • Low binder WC-Co cemented carbide tool materials were prepared based on spark plasma sintering. • WC-1Co-VC, WC-2Co-VC, and WC-3Co-VC exhibited high hardness of 2450, 2377, and 2325 kg/mm2. • The transverse rupture strength and oxidation of three prepared cemented carbides were studied at high temperatures. • Ultra-precise turning of brass with prepared tools resulted in flat surfaces with surface roughness down to 14 nm. [ABSTRACT FROM AUTHOR]

Electrochemical discharge machining (ECDM) is an emerging method for developing micro-channels in conductive or non-conductive materials. In order to machine the materials, it uses a combination of chemical and thermal energy. The tool electrode’s arrangement is crucial for channeling these energies from the tool electrode to the work material. As a consequence, tool electrode optimization and analysis are crucial for efficiently utilizing energies during ECDM and ensuring machining accuracy. The main motive of this study is to experimentally investigate the influence of different electrode materials, namely titanium alloy (TC4), stainless steel (SS304), brass, and copper–tungsten (CuW) alloys (W70Cu30, W80Cu20, W90Cu10), on electrodes’ electrical properties, and to select an appropriate electrode in the ECDM process. The material removal rate (MRR), electrode wear ratio (EWR), overcut (OC), and surface defects are the measurements considered. The electrical conductivity and thermal conductivity of electrodes have been identified as analytical issues for optimal machining efficiency. Moreover, electrical conductivity has been shown to influence the MRR, whereas thermal conductivity has a greater impact on the EWR, as characterized by TC4, SS304, brass, and W80Cu20 electrodes. After that, comparison experiments with three CuW electrodes (W70Cu30, W80Cu20, and W90Cu10) are carried out, with the W70Cu30 electrode appearing to be the best in terms of the ECDM process. After reviewing the research outcomes, it was determined that the W70Cu30 electrode fits best in the ECDM process, with a 70 μg/s MRR, 8.1% EWR, and 0.05 mm OC. Therefore, the W70Cu30 electrode is discovered to have the best operational efficiency and productivity with performance measures in ECDM out of the six electrodes.

In this investigation, the effect of friction stir welding (FSW) parameters such as tool material rotational speed, and welding speed on the mechanical properties of tensile strength, hardness and impact energy of magnesium alloy AZ31B was studied. The experiments were carried out as per Taguchi parametric design concepts and an L9 orthogonal array was used to study the influence of various combinations of process parameters. Statistical optimization technique, ANOVA, was used to determine the optimum levels and to find the significance of each process parameter. The results indicate that rotational speed (RS) and traverse speed (TS) are the most significant factors, followed by tool material (TM), in deciding the mechanical properties of friction stir processed magnesium alloy. In addition, mathematical models were developed to establish relationship between different process variables and mechanical properties.

Objective: The onset of the empirical approach presented in this paper leads to evaluation on the Influence of the Feed Rate, Cutting Speed, and Tool Material on Torque while drilling Prepared Hybrid FRP Laminate using CNC programmed machine. Findings: The influence of cutting condition (feed rate, cutting speed and tool material) on torque were studied and examined. Technique: Design of experiments (DOE) was conducted for the control analysis of the drilling parameters on the response variable (Torque or Twisting Force) by utilizing Taguchi's L27 array the design obtained through Multilevel factorial design in commercial software Minitab 17 to find whether the response variable is minimized by major and/or minor control factors. Result: The percentage deviation of Cutting Speed signifies that torque was least affected rather than other considered factors. The minimum torque was reached in case of cutting speed compared to feed rate and tool material at all levels of factors studied through distinctive main effects plots. [ABSTRACT FROM AUTHOR]

According to performance demands of tool materials for high speed machining difficult to cut materials, gradient cermet composite tool materials were designed and fabricated based on hot pressing sintering after dry pressing. The gradient cermet composite tool materials were composed of surface layer, subsurface layer and substrate and exhibited gradient microstructure and mechanical properties. The surface layer had a high hardness, subsurface layer had a high bonding strength and substrate had a high flexural strength. Three gradient composite cutting inserts were fabricated with the gradient structure on different tool faces. To evaluate the cutting performance of gradient cermet composite cutting inserts, effects of cutting speeds on the tool life and surface roughness were investigated during continuously dry turning 17-4 PH stainless steel. The developed gradient cermet composite cutting inserts showed longer tool life and better machining quality than conventional Ti(C,N) cermet inserts under the same cutting conditions. Cutting speeds played a significant effect on both tool life and failure mode of cutting inserts. The favorable cutting performance of gradient cermet composite cutting inserts was attributed to high surface hardness, good wear resistance of surface layer and reasonable gradient structure. [ABSTRACT FROM AUTHOR]