Effect Of Tool Geometry Research Articles

An Investigation Study of Tool Geometry in Single Point Incremental Forming (SPIF) and their effect on Residual Stresses Using ANOVA Model

Incremental forming is a flexible sheet metal forming process which is performed by utilizing simple tools to locally deform a sheet of metal along a predefined tool path without using of dies. This work presents the single point incremental forming process for producing pyramid geometry and studies the effect of tool geometry, tool diameter, and spindle speed on the residual stresses. The residual stresses were measured by ORIONRKS 6000 test measuring instrument. This instrument was used with four angles of (0º,15º,30º, and 45º) and the average value of residual stresses was determined, the value of the residual stress in the original blanks was (10.626 MPa). The X-ray diffraction technology was used to measure the residual stresses. The sheet material used was Aluminum alloy (AL1050) with thickness of (0.9 mm). The experimental tests in this work were done on the computer numerical control (CNC) vertical milling machine. The extracted results from the single point incremental forming process were analyzed using analysis of variance (ANOVA) to predict the effect of forming parameters on the residual stresses. The optimum value of the residual stresses (55.024 MPa) was found when using the flat end with round corner tool and radius of (3 mm), wall angle of (55°) and a rotational speed of the tool of (800 rpm). The minimum value of the residual stresses (24.389MPa) was found when using hemispherical tool with diameter of (12 mm), wall angle of (45°) and a rotational speed of the tool of (800 rpm).

Investigation of tool geometry in nanoscale cutting single-crystal copper by molecular dynamics simulation

Molecular dynamics has been employed in this paper to investigate the nanoscale cutting process of single-crystal copper with a diamond tool. The behavior of the workpiece during material removal by diamond cutting has been studied. The effects of tool geometry including rake angle, clearance angle, and edge radius are thoroughly investigated in terms of chips, dislocation movement, temperature distribution, cutting temperature, cutting force, and friction coefficient. The investigation showed that an appropriate positive rake angle ([Formula: see text]), a suitable clearance angle ([Formula: see text]), or a smaller edge radius tip resulted in a smaller cutting force and a better subsurface finish. It was found that a tool with a rake angle of [Formula: see text] generated more chips, had a higher cutting efficiency, and produced a lower temperature in the workpiece, but a smaller rake angle tip was more conducive to protecting the groove compared to a large rake angle tip. Compared with a tool with a small clearance angle, the tool with a larger clearance angle generated more chips and caused a lower temperature rise in the copper workpiece, and prolonged its lifetime. In addition, a larger clearance angle tip was more conducive to protecting the groove. A smaller edge radius tip reduces the cutting heat during the nanoscale cutting process, while the volume of chips decreases. These results indicated that it is possible to control and adjust the tool parameters according to the tool rake angle, clearance angle, and edge radius during the machining of single-crystal copper, and a set of tool parameters were obtained: [Formula: see text] rake angle, [Formula: see text] clearance angle, and 0 nm edge radius which could reduce surface damage and the required cutting force.

Smoothed particle hydrodynamics (SPH) simulation and experimental investigation on the diamond fly-cutting milling of zirconia ceramics

This paper presents a more efficient ultra-precision diamond fly-cutting method to achieve the damage-free surface machining of hard-brittle zirconia ceramics at one time instead of the traditional abrasive-based processes. Firstly, the smoothed particle hydrodynamics (SPH) cutting simulation model of zirconia ceramics is established in LS-DYNA based on JH-2 constitutive model. The radial diamond fly-cutting milling experiments of zirconia ceramics are carried out on the three-axis ultra-precision machine tool, and the correctness of SPH simulation model is verified by the brittle-ductile transition (BDT) depth and chip morphology. Then, the effects of tool geometry and cutting parameters on stress distribution, brittle-ductile transition depth, cutting force characteristics, and chip morphology are investigated by the proposed model. Some conclusions are given as follows: the tool with more negative rake angle are benefit for hydrostatic pressure and getting greater brittle-ductile transition depth; the critical brittle-ductile transition depths of zirconia ceramics under -15 degree and -35 degree tool rake angle are 0.8μm and 1μm, respectively. Finally, by controlling the maximum undeformed chip thickness below 1μm, an application experiment is carried out and a crack-free nanometer-level surface is achieved in the axial diamond fly-cutting milling of zirconia ceramics.

Modelling and experimental investigation on textured surface generation in vibration-assisted micro-milling

This paper investigates the textured surface generation mechanism in vibration-assisted micro milling through modelling and experimental approaches. To decouple the effects of tool geometry and kinematics of vibration-assisted milling, a surface generation model based on homogenous matrices transformation is proposed. On this basis, series of simulations are performed to provide insights into the effects of various vibration parameters (frequency, amplitude and phase difference) on the generation mechanism of typical textured surfaces in 1D and 2D vibration-assisted milling. Furthermore, the wettability tests are performed on the machined surfaces with various surface texture topographies. The fish-scale textured surfaces are found to exhibit better wettability than those with wavy-structure. The results indicate that vibration-assisted milling is an effective method to generate certain surface textures with controllable wettability.

Effect of Tool Geometry and Heat Input on the Hardness, Grain Structure, and Crystallographic Texture of Thick-Section Friction Stir-Welded Aluminium

The effect of tool geometries on the microstructure and crystallographic texture of 32-mm-thick friction stir-welded AA6082 has been investigated. The use of a tapered probe tool results in a significant variation in the grain size from the top to the base of the nugget, whereas parallel probe tools produce a uniform grain size throughout the nugget. The grain size in the nugget reflects the amount of deformation experienced and the speed of deformation expressed in terms of strain rate. An approach is proposed to calculate the strain rate during FSW of aluminum for which values between 217 and 362 s−1 were obtained. The strain rate can be either uniform or varied through the joint thickness based on the type of tool used. The tapered tool produces a variation of the strain rate, whilst the parallel tool has a uniform strain rate throughout, which can explain the obtained grain structure in each case. The tool geometries also influenced texture development with the tapered tool producing a tilt of the local shear reference frame by an angle to the normal direction equal to the taper angle.

Effect of Rotating Tool Geometry on Mechanical Properties of Friction Stir Welded Aluminum Alloy 2195

It is known that Al-Li alloys show high specific strength and have been used in space vehicles with Friction stir welding (FSW). FSW has many advantages including the absence of porosity, low distortion and reduced residual stresses which are typical defects of the fusion welding processes. The process uses a rotating tool with a profiled pin that penetrates the parts to be welded. The tool starts to travel along the welding line and the softened material due to the frictional heat is stirred and mechanically mixed together by the rotating pin forming a weld in solid state without melting. Welding parameters such as tool rotational speed, travelling speed, and tool geometry are the main parameters which affect the material flow and the heat generation rate. The important tool geometry includes pin size and shape, pin tread and pitch, tool materials, and shoulder size and shape. The present work is to study the effect of tool geometry on the microstructure and mechanical properties of friction stir welded aluminum alloy 2195. Five different tool profiles have been used to investigate the effects of tool geometry on mechanical properties. The experimental results show that aluminum alloy 2195-T8 can be welded using FSW process with maximum welding efficiency of 75% using threaded cylindrical with concave shoulder at rotation speed, 600 RPM and welding speed, 300 mm/min.

Fabrication of cooling channels employing worm voids caused by friction stir based process: Considering cooling and fluid parameters

The developments in compact high power mechanical and electrical devices naturally require heat removal systems that are equally small. Miniaturized heat exchangers (MHE) are manufactured either by joining multiple tubes or by connecting independent fluid channels fabricated in several steps. Friction stir channeling (FSC), is an innovative cost-effective technology that can be practically employed to reduce the fabrication process of connected channels into a single step. For this reason, the effects of manufacturing parameters of FSC on the main design factors of MHE should be clearly known. In the present study, novel tools are designed based on a comprehensive understating of complex material flow in friction stir based process (FSBP). These tools are proposed both to facilitate material separation and to enhance the amount of material removed from the channel holes. The FSC designed tools are experimentally employed in both laminar and turbulent flows to investigate the effects of tool geometry on the main performance parameters of cooling ducts. Flow resistance along with convection and conduction thermal resistances are introduced in this study to explore the produced channels. Evaluation of each tool by considering the geometrical, thermal, and flow parameters clearly indicates that the bi-directional threaded diamond-shape FSC tool is a viable tool that can pave the way for developing efficient thermal and flow designs in MHE systems.

Effect of tool geometry and welding speed on mechanical properties of dissimilar AA2198–AA2024 FSWed joint

Different tool geometries were used to investigate the joining of aluminum alloys (AA2198 to AA2024) by friction stir welding (FSW). Three shoulder profiles (flat, raised spiral, and raised fan) and five different pin profiles (cone, half threaded cylindrical, straight cylindrical, tapered cylindrical and square) were selected. Preliminary investigations were conducted by moving the tool into a seamless sheet made of the AA2024-T3 in order to select the tools that produce defect-free joints. Preliminary investigations showed the raised fan shoulder profile helps the material flow from the edge of shoulder to the pin creating a smooth surface finish with no flash in comparison with flat and raised spiral shoulder profiles. Pins with a minimum diameter equal to half the plate thickness produced lack of penetration (LOP) defects, while increasing minimum pin diameter to the plate thickness eliminates the LOP defects. Half threaded cylindrical pin produced tunneling defect, whereas defect free joint made by straight cylindrical, tapered cylindrical and cubic pin profiles. So they were selected for joining AA2024 to AA2198. Fracture locations of different joint variants were observed the vicinity of the thermomechanical affected zone (TMAZ) of AA2198-T3 alloy, and in the nugget on the AA2198-T3 side which have the minimum hardness and highest strain localization as confirmed by hardness maps and digital image coronation (DIC). Higher measured temperature than dissolution temperature of AA2198 main strengthening precipitates could be the reason of low hardness and fracture in TMAZ and center of nugget. Furthermore a raised fan shoulder with a tapered cylindrical pin produced highest elongation and yield strength and it was selected as the best candidate for optimization of the welding parameters. It was found that higher rotational and traverse speeds enhance the formation of tunneling and kissing bond defects, suggesting that longer pins have to be used for higher traverse speeds. Welding speed 750 rpm with 450 mm min−1 could create joint with highest yield strength.

Effects of tool geometry on friction stir welding of AA6061 to TRIP steel

With the appropriate process parameters, both large and small tools can produce sound joints with tensile strengths (TS) 80% higher than those fabricated with Al base metal. As a large tool moves into the steel, it can peel off and embed steel fragments into the Al matrix, causing critical defects around the embedded fragments. Using small tools and lower rotational speed (RS) will significantly reduce the welding heat, resulting in an unwelded Al/steel interface at the bottom of the weld. Since the tool size and process parameters determine the amount of generated heat, they also determine the thickness of the intermetallic compound (IMC) layer that forms at the Al/steel interface. The welding forces in the weld plane are primarily affected by the tool offset.

Evaluation of novel tool geometries in dry drilling aluminium 2024-T351/titanium Ti6Al4V stack

Three novel drill geometries, multipoint, step and double cone, were designed and experimentally evaluated to understand the effect of tool geometries on the machining performance of dry drilling Al/Ti stack. Results showed that the double cone drill achieved a better hole quality and a higher efficiency due to the smaller thrust force, broken chips, and less burrs compared to the other two drill geometries. The multipoint drill generated serrated chips in titanium alloy drilling. Significant microstructure deformation occurred in the adiabatic shear band (ASB) and the second shear band. Visible cracks propagated along the ASB from the free to back surface of the chip. Phase transformation from β phase to martensite occurred in the second shear band. The drill geometry design and experimental investigation in this paper could provide guidance for drill bit design and manufacturing for Al/Ti stack drilling.

Experimental investigations on deformation of soft rock during cutting

An experimental study has been made on the deformation of model soft rocks during orthogonal cutting. Through high resolution imaging of orthogonal cutting experiments under 2-D plane-strain conditions, and consequent image analysis, using particle image velocimetry (PIV), we present the evolution of deformation during the cutting process. In addition to examining the deformation fields, and by analysing force signatures, we examine the effect of tool geometry and the depth of cut on the mechanics of cutting in porous brittle solids. In tracking the deformation continuously, we identify the process of fracture initiation and propagation, as well as the corresponding formation of chips. The cutting force was influenced by depth of cut in far more significant way at negative rake angles. We further demonstrate two types of cutting mechanisms occurring with change in tool geometry and draw correspondence between initiation and propagation of fractures and the cyclic nature of force signatures. In the case of machining at negative rake angle, in addition to cyclic increase and decrease of the cutting force, a clear development of a triangular dead zone at the tool tip is measured and the size of this zone also varies cyclically. The volume change occurring in this dead zone formed at the tool corner during negative rake angle cutting is also tracked. By using image analysis, and isolating the geometry of the crack developed during the experiments, we find that the length of crack propagated during cutting of porous brittle solids is a function of the deformation geometry. The effect of rake angle being far more prominent than the depth of cut. The experiments also show that the extent of surface and subsurface deformation during cutting is limited, and the deformation is localized.

Molecular dynamics simulation of subsurface damage mechanism during nanoscratching of single crystal silicon

Three-dimension molecular dynamics (MD) simulation is employed to investigate the nanoscratching process of monocrystalline silicon with diamond tools. The effects of tool geometry on subsurface damage and scratching surface integrity are investigated by analyzing phase transformation, chip, defect atoms, hydrostatic stress, von Mises stress and workpiece deformation. In addition, a theoretical analytical model to study the subsurface damage mechanism by analyzing the zone size of phase transformation and normal force with diamond tools at different half-apex angles on silicon surfaces is established. The results show that a bigger half apex angle causes a higher hydrostatic stress, a larger chip volume, a higher temperature and a higher potential energy, and increases subsurface damage. The results also reveal that the evolution of crystalline phases is consistent with the distribution of hydrostatic stress and temperature. In addition, tip scratching with a bigger half-apex angle would result in a larger scratching force and a bigger phase transformation zone, which is in good agreement with the results of the theoretical analytical model.

Experimental Study the Effect of Tool Geometry on Dimensional Accuracy in Single Point Incremental Forming (SPIF) Process

Incremental forming is a flexible sheet metal forming process which performed by utilizes simple tools to locally deform a sheet of metal along a predefined tool path without using of dies. One limitations of single point incremental forming (SPIF) process is the error occur between the CAD design and the product profile. This work presents the single point incremental forming process for produced pyramid geometry and studied the effect of tool geometry, tool diameter, wall angle, and spindle speed on the dimensional accuracy. Three geometries of forming tools were used in experimental work: ball end tool, hemispherical tool, and flat with round corner tool. The sheet material used was pure Aluminum (Al 1050) with thickness of (0.9 mm). The experimental tests in this work were done on the computer numerical control (CNC) vertical milling machine. The products dimensions were measured by utilized the dimensional sensor measuring instrument. The extracted results from the single point incremental forming process indicated the best acceptance between the CAD profile and product profile was found with the ball end tool and diameter of (10 mm), wall angle (50°) and the rotational speed of the tool was (800 rpm).

Effect of tool geometry on the velocity and strain rate fields in continuous rotary extrusion of magnesium AZ91 alloy

The Continuous Rotary Extrusion (CRE) process is also known in literature under Conform TM name and it is mainly used for the continuous extrusion of aluminum and copper alloys. In the CRE process a feedstock in the form of rod, powders or chips, is fed into the groove of the rotating wheel. CRE has lot to offer when compared to other more conventional extrusion processes such as low energy input, no limit for billet length because it is a continuous process as well as improved material physical properties due to plastic deformation under constant parameters. Therefore, the CRE process is of our interest in forming Mg alloys. In the presented study, the effect of tool geometry on the velocity and strain rate fields in the deformation zone are investigated by FEM simulation of the CRE extrusion of magnesium alloys AZ91. The FEM process model was developed in commercially available DEFORM 3DTM software. The flow stress data for AZ91 magnesium alloy were obtained from reported literature. The metal flow predictions for two different feeder plate and presence of draft angle in exit die have been presented.

Review on friction stir welding of steels

This review article summarizes the extensive research works carried out on ferrous alloys and critically examine several aspects of FSW in these materials. Particularly suitable tool materials, tool geometry, effect of tool geometry in metallurgical and mechanical properties of weldment were being discussed. Ever since The Welding Institute (TWI) developed the Friction Stir Welding (FSW) process, extensive studies were being carried out by joining different materials in various laboratory. Initially FSW process was developed for aluminium alloys slowly the technique is adopted for other softer materials such as magnesium, lead and zinc. Later, improvement in tool material lead to use of the eco-friendly welding process (FSW) to other hard materials such as copper, brass, stainless steel, hardened steel and superalloys. Even though several studies shows the capacity of FSW process to join hard materials, the process creates high stress and temperature at the stir zone (approximately 1300 °C) which endorses fast tool degradation is the major concern during the process. High tool cost due to fast tool degradation, makes commercial application of FSW on hard metal as challenging. Introduction of polycrystalline cubic boron nitride (PCBN) and tungsten alloys tool materials made FSW possible on stainless steel, hardened steel and superalloys with outstanding results in terms of weld strength and microstructural properties.

Numerical evaluation of residual stresses induced during metal cutting

Residual stress analysis plays a very important role in the structural safety and stability of the component. Residual stress has a great influence on the fatigue life of the structures. Residual stress reduces the load carrying capacity along with source of crack generation. The analysis of residual stress is complicated as it depends upon the tool geometry and cutting parameters. This work focuses on the effects of tool geometry and cutting parameters on residual stress in orthogonal machining of Aluminum 1100-0 using the finite element method (FEM) simulation. Explicit dynamics analysis is carried out in ANSYS Workbench. The results reveal the variation of residual stress as a function of tool geometry, depth of cut, nose and the machining speed. The results provide the inter relation between the residual stress and afore mentioned parameters

Effect of tool geometry on microstructure and mechanical Properties of friction stir processed AA2024-T351 aluminium alloy

Friction stir processing is a method of altering the characteristics of a metal through severe localized plastic deformation. It has proved to be an effective method of enhancing the material properties through significant structural refinement and homogenization. In FSP, tool and tool pin plays an important role to defecate the grain size for achieving a defect free processed zone. The objective of this study is to investigate the effect of tool geometry on the quality of the friction stir processed AA-2024 T351 alloy which finds prime position in the fabrication of light weight structures requiring a high-strength-to–weight ratio. Especially the physical, microstructural and the morphological changes occurring at the nugget, Heat affected zone (HAZ) and shoulder region for two different tool geometry have been studied. The experiment was conducted for different process variables such as feed, speed and shape of the tool. The study has indicated that the triangular pin geometry gives out the best results for the selected alloy.

Effect of tool geometry in ultrasonic bonding of multilayered foils

Effect of tool geometry in ultrasonic bonding of multilayered foils

Mechanical properties of friction stir welded butt joint of steel/aluminium alloys: effect of tool geometry

This paper described the mechanical properties from hardness testing and tensile testing of Friction Stir Welded (FSW) materials. In this project, two materials of aluminium and steel are welded using conventional milling machine and tool designed with different profile and shoulder size. During welding the temperature along the weld line is collected using thermocouples. Threaded pins was found to produce stronger joints than cylindrical pins. 20 mm diameter shoulder tool welded a slightly stronger joint than 18 mm diameter one, as well as softer nugget zone due to higher heat input. Threaded pins also contributed to higher weld temperature than cylindrical pins due to increase in pin contact surface. Generally, higher temperatures were recorded in aluminium side due to pin offset away from steel.

The performance of a fluted coulter for vertical tillage as affected by working speed

Vertical tillage is an efficient and effective tillage practice for conservation agriculture. However, the performance of vertical tillage tools has not been well documented. In this study, two vertical tillage tools: 8-wave and 13-wave coulters, were tested in a wheat stubble field at three different working speeds: 12, 16, and 20km/h, to examine the effects of tool geometry and working speed on the tillage performance of the fluted coulters. Soil disturbance width, soil throw width, and soil sticking on the coulter as well as residue cover were measured. The results showed that the soil disturbance width was significantly different among the working speeds and between two coulters while the other measured variables were only affected by the working speed. The 13-wave coulter had a 17% lower soil disturbance width as compared with the 8-wave coulter. Increasing the working speed (from 12 to 16km/h and from 12 to 20km/h) increased the soil disturbance width by 7.0 and 13.1% and the soil throw width by 14.3 and 45.1% respectively, but decreased the soil sticking by 1.4 and 76.6% and the residue cover by 5.1 and 11.0% respectively. Generally speaking, the effect of working speed was more dominant than the coulter geometry on the tillage performance of the fluted coulters. For long-term no-tillage farmers with excessive residue concerns, the 8-wave coulter working at 20km/h would be beneficial for sustainable farming practice.