Tool Tilt Angle Research Articles

Revealing the mechanism of tool tilting on suppressing the formation of void defects in friction stir welding

Experiments have proven tool tilting in friction stir welding (FSW) can effectively suppress the formation of void defects. However, the mechanism of tool tilting on suppressing the formation of void defects has not been revealed. In this study, a CFD model considering the influence of tool tilting is established. A non-uniform distribution of normal pressure at the tool-workpiece contact interfaces is proposed to relate to the tool tilt angle. The discrete particle tracing method is used to characterize the formation of void defects in FSW. The heat generation, temperature distribution and plastic flow behaviors between the case without (i.e. 0° tool tilt angle) and with (i.e. 2.5° tool tilt angle) tool tilting are quantitatively compared and analyzed. The results show the tool tilting in FSW leads to higher heat flux and temperature near the pin side in the middle and low parts of the workpiece. Moreover, the frictional shear stress at the pin side/workpiece contact interface significantly increases when the tool is tilting, leading to a higher driving force for the plastic material to flow. As a result, the material flows farther to the advancing side of the workpiece after bypassing the tool when the tool is tilting at 2.5°, which helps to heal the voids on the advancing side of the FSW joints. The higher temperature with higher frictional shear stress enhances the plastic material flow in the middle and low part of the joints when the tool is tilting, which is attributed to suppressing the void defects. The model is validated by experimental results.

Effect of welding speeds on the metallurgical and mechanical property characterization of friction stir welding between dissimilar aerospace grade 7050 T7651-2014A T6 aluminium alloys

Friction stir welding (FSW) is an effective technique for producing quality welds and resolving solidification issues of aluminium alloys found in fusion welding (FW) techniques. This study seeks to establish the effect of welding speeds (WSs) of 25, 45, 65, and 85 mm/min with a constant tool rotation speed (TRS) of 1000 rpm and a tool tilt angle (TTA) of 20. Furthermore, mechanical testing was performed to determine the tensile strength, microhardness, and residual stresses. In addition, microstructure characterization was performed using optical microscopy, SEM/EDS and EBSD to identify the quality assurance of the dissimilar AA7050 T7651-AA2014A T6 weld joint. The results indicated that while the WS increased from 25 to 85 mm/min, the width of the stir zone decreased from 9.497 mm to 6.315 mm, according to the macrostructure analysis. Moreover, microstructural analysis reveals the direction of material flow and grain structure on the advancing side (AS) and retreating side (RS) of the thermo-mechanical affected zone (TMAZ) in the weldment. EBSD analysis reveals the 65 mm/min weld joint has a finer grain size (the average grain size is 2 µm) compared to other WS. Residual stress analysis also reveals compressive residual stress in all weld zones except for RS. The RS of residual stress values for 25–85 mm/min weld joints is 3, 7, 4, and 5 MPa. At the same time, UTS values were obtained as 274 MPa (25 mm/min), 317 MPa (45 mm/min), 332 MPa (65 mm/min), and 308 MPa (85 mm/min), and fracture occurred on the RS of all the welded joints, which was confirmed by harness values that are (AS and RS) 115–157 HV and 63–154 HV, respectively. The observed results show that WS at 65 mm/min has better mechanical and metallurgical properties than other welding speeds because of proper material mixing and finer grains obtained in the weldment, which resulted in higher UTS values being attained for WS at 65 mm/min of the FSW joint.

A Multiple Response Prediction Model for Dissimilar AA-5083 and AA-6061 Friction Stir Welding Using a Combination of AMIS and Machine Learning

This study presents a methodology that combines artificial multiple intelligence systems (AMISs) and machine learning to forecast the ultimate tensile strength (UTS), maximum hardness (MH), and heat input (HI) of AA-5083 and AA-6061 friction stir welding. The machine learning model integrates two machine learning methods, Gaussian process regression (GPR) and a support vector machine (SVM), into a single model, and then uses the AMIS as the decision fusion strategy to merge SVM and GPR. The generated model was utilized to anticipate three objectives based on seven controlled/input parameters. These parameters were: tool tilt angle, rotating speed, travel speed, shoulder diameter, pin geometry, type of reinforcing particles, and tool pin movement mechanism. The effectiveness of the model was evaluated using a two-experiment framework. In the first experiment, we used two newly produced datasets, (1) the 7PI-V1 dataset and (2) the 7PI-V2 dataset, and compared the results with state-of-the-art approaches. The second experiment used existing datasets from the literature with varying base materials and parameters. The computational results revealed that the proposed method produced more accurate prediction results than the previous methods. For all datasets, the proposed strategy outperformed existing methods and state-of-the-art processes by an average of 1.35% to 6.78%.

Influence of SiC Microparticles and Multi-Pass FSW on Weld Quality of the AA6082 and AA5083 Dissimilar Joints

In the current research, the influence of multi-pass of friction stir welding and SiC microparticles on the tensile strength, microhardness, and %strain of dissimilar reinforced joints of AA6082 and AA5083 was examined. A tool rotating speed of 900 rpm, a transverse speed of 45 mm/min, a tool tilt angle of 2º and 8% volume percentage of SiC microparticles were considered as parameters for multi-pass FSW. The finding demonstrated that increasing the number of FSW passes from one to three augmented the dispersion pattern of SiC microparticles. The grain refinement of multi-pass reinforced joints was achieved by the pinning effect of SiC microparticles and dynamic recrystallization. The three-passes FSWed reinforced joint exhibited the highest tensile strength (247.17 MPa), % strain (13.1%), and microhardness (126.6 HV) due to the higher grain refinement.

Microstructure, mechanical, and force-torque generation properties of friction stir welded third generation Al/Li alloy at higher traverse speed

The third generation of aluminium lithium alloys has been used primarily in aircraft and spacecraft structures for customized facilities to reduce weight and improve performance. Therefore, the present study has investigated the implication of varying tool rotation speed (TRS) from 700 rpm to 1600 rpm on the force, torque, heat generation, microstructure, and mechanical strength of friction stir welded 2050-T34 Al-Cu-Li alloy plates at a constant higher traverse speed (10 mms−1) and tool tilt angles of 2°. The experimental results reveal that increasing TRS decreases the weldment surface's force, torque, ripple space, and grain size. However, the heat input increases during friction stir welding with increasing TRS. The joint efficiency (87.9 %) and tensile strength (343.5 MPa) are obtained maximum at higher TRS(1600 rpm). Further, mixed and ductile failure modes are observed at the lower and higher TRS, respectively.

Experimental and finite element investigations on formability of friction stir welded tailor welded blanks of AA6061 and AA2017

Basically, the use of forming limit diagrams has been increased and dertermined as a recognizing technique for obtaining tailor welded blank's formability. In this present investigation, an effort was made to calculate the formability of friction stir welded (FSW) dissimilar alloys by varying the three main process parameters such as tool rotational speed (TRS), weld speed (WS), and tool tilt angle (TTA). All possible combinations of dissimilar sheets were used for experimental and simulation studies to test the limiting dome height. Material characteristics such as densities, young's modulus, as well as all behaviors of blanks were manually allocated for simulation, using true stress vs true strain plots. The simulation process is performed by considering the whole blanck as three zones with heights of limiting dome seem to be nearer with simulation studies and experimental results. With consideration of Forming limit diagram along with assistance of profiles of strain distribution the formability of all dissimilar blanks was evaluated. Blanks that were tailor welded at a TRS of 13,00 rpm, WS of 20 mm/minute, and tool tilt angle considering 10 exhibited higher formability compared to the blanks friction stir welded at various conditions.

Optimization of FSW parameters for enhancing dissimilar joint strength of AA7050 and AA6061 using Response Surface Methodology (RSM)

This study used a central composite design of RSM to friction stir welding (FSW) of two different Al-alloys, AA6061 and AA7050, by varying input parameters, including tool tilt angle (TTA), rotating tool speed (TRS), and welding speed (WS). Twenty experiments were performed, and output responses such as UTS, percent strain, and hardness were perceived. The FSW parameters were optimized using the desirability method. An analysis of variance was performed with a 95 percent confidence interval (CI) to assess the suitability of the produced model. This study found that the WS and TRS were the most crucial variables affecting the ultimate tensile strength (UTS) and hardness of the weldments. At a TRS of 1500 rpm, 150 mm/min, and a TTA of 2°, the highest UTS (255.83 MPa) and percent strain (21.02) were recorded. At a WS of 120 mm/min, a TTA of 2°, and a TRS of 1100 rpm, the lowest UTS (148.58 MPa) and hardness value (66.4HV) were noted. The results of the tensile test demonstrate the significance of the TRS and WS in affecting the UTS of the welded joint. A higher TRS causes more significant material consolidation behind the shoulder and improved mechanical properties.

The Influence of the Tool Concave Shoulder Angle on Heat Generation in the Stir Friction Welding Process with AA6061-T651 Materials

This study aims to determine the effect of the concave shoulder angle of the FSW tool on heat generation rate and temperature simulation results. The FSW tool used in this study is the FSW tool with straight cylindrical geometry, tapered cylinder, hexagonal, and tapered square. Calculation of heat generation rate is carried out for all FSW tools, then the optimal one is selected and then simulated. The process of calculating heat generation rate and simulation using the Taguchi method has 4 factors, each of which has 4 levels. The factors used in this study are tool rotation speed, welding speed, concave shoulder angle, and tool tilt angle with temperature response. on the weld joint. The results of this study indicate that the influence of the concave shoulder angle on the heat generation rate and temperature simulation is very influential. Based on the results of the heat generation rate calculation, the FSW tool with hexagonal pin geometry was chosen to be simulated. The simulation results show that the selected process parameters are tool rotation speed of 1208 rpm, welding speed of 90 mm/s, concave shoulder angle of 5°, and tool tilt angle of 3°. From the selected parameters, it was experimented with to produce a fairly good connection even though there were still surface defects.

Friction Stir Welding Process Optimization on 4 Tool pin Geometries with Process Parameters and Shoulder Concave Angle in 6005A-T6 Aluminium Alloy Joining

FSW is a welding process which done by movement of tool against the workpiece. Tool is an important part in FSW process because tool generates most of the heat in the FSW process, so the tool material and geometry are important because they receive high stress and temperature. This research was conducted to decide the best pin geometry for tool from the 4-pin geometry that has been decided, which is straight cylindrical, tapered cylindrical, hexagonal, and tapered square. The optimization process is done with Taguchi method using 4 factors where each factor has 4 levels, factors that used in this research are tool rotation speed, welding speed, tool shoulder angle, and tool tilt angle with the respond is temperature at welding joint. The optimization process will be done in all of the pin geometries that has been decided and the best pin geometry out of 4 geometries will be chosen. The best pin out of 4 geometries is the hexagonal pin with the optimized parameters are the rotational speed of 1208 rpm, welding speed of 65 mm/min, tilt angle of 2.5° and concave angle of 2° with max. temperature of 322.48°C. The significant factor obtained was the tool rotational speed and concave angle with significance level of 95%.

A review on recent development in aluminium-copper friction stir welding

Aluminium (Al) and copper (Cu) are widely employed in the industry due to their significant corrosion resistance and electrical conductive properties. The simultaneous requirement of different special properties has increased the trend of joining of Al and Cu. The joining of dissimilar materials has arisen as a new challenge in the research field in the past decade. Friction stir welding (FSW) is a very worthy process to join metals that aren't the same. This article delves into the intricacies of FSW to join compatible metals such as Al and Cu. The various parameters of FSW, namely tool design, tool pin offset, rotation speed, welding speed, tilt angle, and different types of welding joints, are highlighted in this article. It also goes through the different types of defects, microstructures, and intermetallic compounds (IMCs) that are formed during Al-Cu FSW. The electrical behavior and corrosion behavior of the weld zone in Al-Cu FSWed joints were also reviewed. Role of interlayer in some emphasis was also given to form effective joints.

Multi-response optimization of process parameters during friction stir welding of AA2014-AA7075 using TOPSIS Approach

In this study, multi-objective optimization for Friction stir welding of dissimilar AA2014-AA7075 has been presented to provide optimum tensile strength, hardness, and % of elongation. The input parameters considered for the analysis are tool rotational speed, feed, and tilt angle. Experiments are designed based on Taguchi L9 orthogonal array. Investigative analysis on the effect of input parameters on the responses is carried out using the MINITAB14 software package. The parametric influence on responses is discussed through the main effects plot. Further, multi-objective optimization is performed with the Technique for order of preference by similarity to ideal solution (TOPSIS). Results demonstrated that tool rotational speed is the most significant factor affecting the response followed by feed and tilt angle. The optimum cutting parameters obtained are tool rotational speed 710 rpm, Feed 30 mm/rev, and Tilt angle 2o.

Influence of tool tilt angle on physical, thermal, and mechanical properties of friction stir welded Al-Cu-Li alloys

Influence of tool tilt angle on physical, thermal, and mechanical properties of friction stir welded Al-Cu-Li alloys

Optimization of Friction Stir Welding Parameters of AA5052-H32 Aluminium Alloy using Taguchi and Taguchi-Pareto Methods

It is difficult to improve the quality of friction stir welded joints of AA5052-H32 material because of scarce metrics on its concurrent optimization and prioritization. However, the objective of this article is to obtain optimal parametric values and identify important parameters using the Taguchi-Pareto method during the friction stir welding process of AA5052-H32 material. Then the ranks, delta values and optimal parameters are determined. The critical parameters identified for the friction stir welding process are the tool pin, rotational speed, welding speed and tool angle. When comparing the results of these parameters using the Taguchi method and Taguchi-Pareto method, the rotational speed retained its first position in both methods; the tool tilt angle gained the second position in the Taguchi-Pareto method from its third position when only the Taguchi method was considered. The welding speed became the third position in the Taguchi-Pareto method against the second position that it had in the Taguchi method. However, the tool pin profile retained its last position in both methods. Consequently, the rotational speed is the best parameter while the tool pin profile is the worst parameter. For the Taguchi-Pareto method, the optimal parametric setting is TPP2/TPP4RS1WS4TTA3. This is interpreted as cylindrical tapered or square tapered for the tool profile, 40 rpm of rotational speed, 75 mm/min of welding speed and 1.5° of tool tilt angle. The novelty of this study is the scope of analysis of the AA5052-H32 material that extends beyond the Taguchi method to the Taguchi-Pareto method where the concurrent optimization and prioritization of friction welding parameters are achieved.

Effect of tool tilt angle on microstructure, mechanical properties and fracture behavior of dissimilar friction stir lap welding joint of SiCp/ZL101 and ZL101

In order to achieve the lightweight goal of urban rail train braking system, friction stir lap welding (FSLW) was used to weld SiCp/ZL101 and ZL101 sheets to prepare a new type of brake disc material. The effects of different tool tilt angles (TTAs) on microstructure and mechanical properties of the welding joints were systematically studied. The TTA had a significant effect on the microstructure and defect formation of the dissimilar FSLW joints. There were tunnel defects under the advancing side at 1° and 2°. Internal defect-free weld structures were formed at 3° and 3.5°. A large number of dislocations caused by plastic deformation remained in the microstructure of the weld region at 1° and 2°, and the transformation of the microstructure of the weld region at 3° and 3.5° was dominated by dynamic recovery and dynamic recrystallization. The distribution of SiC particles in the nugget area was uniform, and the grains were obviously refined. With the increase of the TTA, the average grain size of the nugget area increased, the average size of the SiC particles decreased, and the average hardness of the nugget area increased. The four samples all formed a transition zone with good metallurgical bonding at the welding interface. The shear strength of the welding joints increased first and then decreased with the increase of the TTA. In the absence of welding defects, the shear strength reached the best level of 130.71 MPa at 3°. Both shear and tensile fractures were ductile fractures.

Multi-parameter sensing of robotic friction stir welding based on laser circular scanning

Sensing is the premise of process control and is of great importance for improving the weld quality in robotic friction stir welding (RFSW). The kinematic characteristics of the 5-axis robot make existing sensing methods unsuitable for the plunge depth and seam deviation. To address this problem, this paper presented a multi-parameter sensing method for the 5-axis RFSW based on laser circular scanning. The laser displacement sensor rotated around the tool forming a series of measured dots to acquire the three-dimensional profile of the workpiece. The measured dots in a circle could be divided into four groups: plane region, welded region, seam region, and disturbed region. Process parameters were extracted using specific algorithms in a circle. The sensing system simultaneously measured the tool tilt angle, plunge depth, and seam deviation online at the maximum frequency of 10 Hz. The absolute measurement accuracy was 0.04°, 0.01 mm, and 0.05 mm for the tool tilt angle, plunge depth, and seam deviation, respectively. And the maximum standard deviation for ten repeated measurements was 0.005°, 0.005 mm, and 0.009 mm, respectively. The feasibility of the sensing system applied to RFSW had been verified through dynamic measurement experiment. This system greatly reduces the number of sensors and facilitates reliable process sensing. Despite being made for 5-axis robots, the sensing system can be used with 6-axis robots and dedicated machines.

Influence of Welding parameters on Mechanical property during Friction Stir Welded joint on Aluminium Alloys: A Review

The friction stir welding (FSW) is widely used in the fabrication of Aluminium alloy and other non-ferrous alloy. It has good potential to be used in major industries such as automobiles, aerospace, shipbuilding and can be used in the joining of high strength alloys. The FSW process low distortion and heat affected zone (HAZ) with fine recrystallized microstructure which leads to better mechanical properties at the weld zone and produces great stability. In this study, the different FSW parameters such as weld speed, tool rotation speed, tool tilt angle, feed per min has been discussed. The different types of tool pin profile and shoulder have also been discussed and their impacts on mechanical and microstructural properties at welded joints. Among various welding parameters the rotational speed is the most influencing parameter in FSW. Increasing the rotational speed exhibits the increase at tensile strength and is supposed to improve the mechanical properties. The most affected tool pin profile would be considered to be tapered threaded cylindrical pin profile which makes the adequate mixing of material with better flow ability and provide the fine grains at nugget zone. Comparing the FSW with other arc welding processes, it shows a wide range of environmental benefits which are noticeable such as saving in consumable materials, decrease in consumption of filler material and reduction in grinding wastes. Harmful emissions created from arc welding causes a health hazard to the welder. For achieving the high joint-strength for aerospace aluminium alloys and high temperature sustainable metallic alloys, friction stir welding will be preferred.

Determining the range of process parameters for friction stir welding using steepest ascent approach

In the present research work, friction stir welding (FSW) of dissimilar aluminium alloy series (i.e., 7xxx and 8xxx) is performed at various rotational speeds (1900–2500 rpm), welding speeds (60–80 mm min−1), and tilt angle (1.8°–2.4°) to find out the optimal ranges of process parameters for main experiments. The experiments are designed as per the steepest ascent approach by using three factors two-level fractional factorial design. The tensile strength is considered as an output parameter for deciding the optimal levels of process parameters. The graphical analysis of the steepest ascent provides the optimal ranges of process parameters, i.e., 1818 to 2104 rpm for rotation speed, 42 to 63 mm min−1 for tool travel speed and 0.9 to 1.8° for tool tilt angle. Furthermore, microstructural and fractography analyses are also carried out to study the morphology and nature of joints. The microstructure shows the different welding zones such as the nugget zone, thermomechanical affected zone, and heat affected zone. The fractography analysis reveals the ductile nature of joint.

Investigation on polypropylene friction stir joint: effects of tool tilt angle on heat flux, material flow and defect formation

Tool tilt angle (TTA) is a critical factor that can control material flow in polymeric materials' friction stir joining (FSJ). This study selected a TTA range between 0° to 4° for FSJ of polypropylene (PP) polymer sheet. A modified computational fluid dynamic (CFD) technique was implemented to gain a deep understanding of the effects of TTA during FSJ of PP. The PP joint's internal flow, defect formation, heat generation, and tensile strength were investigated experimentally. The fracture surface of tensile samples was analyzed by scanning electron microscopy (SEM). Heat generation, heat flux, and defect formation results from simulation were evaluated by experimental tests output. The results indicate that the PP flow during FSJ is susceptible to TTA. Non-uniform volumetric weight transfer was caused at higher TTA in the joint line, which leads to tilted heat flux. At higher TTA, the generated heat increases, leading to PP exit from the joint line and internal gaps. According to selected parameters, the most robust joint (66 MPa) was produced at 1° TTA. The main reason for the mechanical properties of the PP joint was a dimension of the stir zone and internal defects. Shrinkage gaps were the root of crack initiation during the tensile test, and some local stretching in the fracture surface of the tensile sample after the test was detected.

Optimization of Sustainable Process Parameters of Friction-Stir Welding of Aluminium Alloy by Taguchi Method

In the current paper, AA6101-T6 aluminium alloy was subjected to friction stir welding (FSW) utilizing a vertical milling machine. Alloy plates were welded in butt position to provide a virtually flat interface, using a tool shape that was carefully selected. Because of the excessive generation of heat via the tool and workpieces during friction stir welding, substantial deformation in the nugget zone is seen. The mechanical attributes of the base metal at the joint are significantly impacted by an excessive variation in temperature at the weld. In this experiment, mechanical properties-related changes through the FSW process are kept to a minimum to achieve high tensile strength. The tool’s rotating speed (measured in rpm), the workpieces' traverse speed (measured in mm/min), and the tool tilt angle were chosen as the parameters to regulate the weld quality. As a result of its 44% contribution, the rotating speed parameter is shown to be the most beneficial one for stir welding. The metric determining transverse speed contributes the least, at 19%. For effective stir welding, such as high strength welds, defect-free welds, short welding times, low welding costs, etc., it is preferred that the tool rotational speed parameter be concentrated. By using sustainable Taguchi approach to optimize the chosen process parameter, high tensile strength is achieved at the welded connection.

Towards modeling and restraining surface ripples during bonnet polishing based on frequency domain characteristic control

Extensive research has been conducted on Bonnet polishing for its ability to manufacture freeform surfaces with nano-scale precision. However, surface ripples are easy to introduce under regular motion, and the underlying principle to address this problem remains unclear. In this study, a novel methodology based on frequency domain characterization is proposed, connecting the spatial process parameters and frequency domain evaluation index directly. Bessel function and single pulse convolution are introduced for model establishment. Tool radius, tool tilt angle, and contact radius are correlated with surface ripple mitigation. Polishing parameters optimization case study was conducted and verified using self-designed polishing robot.