Tool Rotation Direction Research Articles

Ispitivanje i optimizacija površine zavara i mehaničkih performansi termoplastičnih delova proizvedenih aditivnom proizvodnjom i zavarenih zavarivanjem trenjem

This study presents an experimental investigation into the weldability of ABS M30 (acrylonitrile butadiene styrene) plates produced by Additive Manufacturing (AM) using Friction Stir Welding (FSW). The effects of FSW process parameters on the yield stress and their optimal levels were determined using the Taguchi method. The optimal welding parameters were found to be a 16 mm tool shoulder diameter, 800 rpm tool rotation speed, and 10 mm/min traverse speed. The weld area of each sample welded using FSW was examined at a macroscopic level. The direction of tool rotation significantly affects the quality and strength of the FSW. When the FSW was performed with a clockwise rotation of the welding tool, a perfect weld could not be achieved. The tunnel effect resulted in gaps in the weld area of the samples at high rotation speeds. Differences were observed in the density between the weld area of the samples and the main parts.

Effect of the tool rotation direction on the joint properties of the pinless friction stir spot welding of pure copper

The main goal of this work is to explore the effect of the tool rotation direction with spiral groove on the joint properties of the pinless friction stir spot welding (PFSSW) of thin pure copper sheet. For this purpose, the surface appearance, cross-sectional morphology, microhardness, welding temperature and joint strength of the welded joints under the tool rotation conditions of clockwise and anticlockwise were studied comparatively at different rotation speeds. The fracture modes of welded joints under different tool rotation directions were also analyzed. The results show that the tool clockwise rotation has higher welding strength than anticlockwise rotation at lower rotation speeds, while the opposite is true at higher rotation speeds. Under the clockwise rotation of the tool, the fracture modes of the welded joints are shear fracture and plug shear fracture. When the tool rotates anticlockwise, the fracture modes of the welded joints are shear fracture and plug shear-pullout fracture. Furthermore, the depth of the stir zone produced by anticlockwise rotation of the tool is higher than that produced by clockwise rotation. Overall, the microhardness with anticlockwise rotation of the tool is higher than that with clockwise rotation. In addition, the tool rotation direction has little effect on the welding temperature. The research content can provide a reference for the selection of the tool rotation direction of the PFSSW.

Friction stir powder additive manufacturing of Al 6061/FeCoNi and Al 6061/Ni metal matrix composites: Reinforcement distribution, microstructure, residual stresses, and mechanical properties

Fusion based additive manufacturing (FBAM) of second, sixth, and seventh series Al alloys and their metal matrix composites (MMC) is difficult due to their higher thermal conductivity and solidification related problems namely porosity, cracks, thermal distortion, and formation of undesired phases. This paper presents friction stir powder additive manufacturing (FSPAM) process as a promising alternative to overcome these problems in producing multi-layer depositions of Al 6061 based MMCs namely Al 6061/6 wt%FeCoNi and Al 6061/6 wt%Ni. Their microstructure, distribution and elemental mapping of reinforcement particles, phase analysis, residual stresses of the MMCs and their correlation with microhardness, tensile strength, and fretting wear characteristics are investigated. Material accumulation on their advancing side was minimized by changing tool rotation direction in consecutive layers which produced smoother surfaces on both sides of their deposition. FSPAM made multi-layer depositions of Al 6061/FeCoNi and Al 6061/Ni MMCs have uniform distribution of reinforcement particles, good bonding between layers without cracks and defects, refined and equiaxed grains facilitated by dynamic recrystallization and pinning effect of reinforcement particles, compressive residual stresses of 39 and 48 MPa, no formation of deleterious intermetallic compounds due to absence of melting of matrix and reinforcement, and bowl-shaped substrate-deposition interface. Microhardness and ultimate tensile strength of the MMCs improved by 11.3% and 22.3%, and 30.5% and 31.5% respectively than Al 6061 alloy depositions, their wear resistance enhanced significantly, but % elongation reduced. This study proves FSPAM to be a potential alternative to FBAM processes for better quality multi-layer deposition of Al alloy-based MMCs.

Effect of Tool Rotation Direction on Mechanical Strength of Single Lap Friction Stir Welded Joints between AA5083 Aluminum Alloy and S355J0 Steel for Maritime Applications

This study aims to investigate a friction stir welded joint between steel and aluminum alloy that is employed in maritime applications (i.e., connection between the ship over-structures and the hull or deck). By changing the tool rotational direction, or the advancing or retreating side, a single lap configuration was studied. Tensile tests were conducted to evaluate the mechanical resistance and the surface fracture after a preliminary investigation consisting of morphological and microstructural analyses and microhardness measurements, with the goal of considering the possibility of replacing the typical joining processes, such as traditional welding or explosion welding, with friction stir welding. The testing showed that the joint produced on the advancing side performed better (+23.5% of the maximum load) than the joint made on the retreating side.

Investigation of Surface Roughness in Incremental Sheet Forming of Conical Drawpieces from Pure Titanium Sheets.

The article presents the results of the analysis of the influence of incremental sheet forming process parameters on surface roughness measured on both sides of conical drawpieces made from pure titanium Grade 2 sheets. The experimental plan was created on the basis of a central composite design. The study assumed the variability of feed rate, spindle speed, and incremental step size in the following range: 500–2000 mm/min, 0–600 rpm, and 0.1–0.5 mm, respectively. Two strategies differing in the direction of the tool rotation in relation to the feed direction were also analysed. Analysis of variance is performed to understand the adequacy of the proposed model and the influence of the input parameters on the specific roughness parameter. The sensitivity of the process parameter on the selected surface roughness parameters was assessed using artificial neural networks. It was found that the change in the surface roughness of the inner surface of the drawpiece is not related to the change of surface roughness of the outer side. The morphology of the outer surface of the draw pieces was uniform with a much greater profile height than the inner surface that had interacted with the tool. Taking into account the outer surface of the drawpiece, the direction of tool rotation is also most closely correlated with the parameters Sa, Sz, and Sku. Step size and feed rate provide the highest information capacity in relation to skewness and kurtosis of the inner surface of the drawpiece.

Split-Plot I-Optimal Design Optimisation of Combined Oil-Based and Friction Stir Rotation-Assisted Heating in SPIF of Ti-6Al-4V Titanium Alloy Sheet under Variable Oil Pressure

The aim of this paper is to determine the optimal input parameters for the process in order to ensure the maximum formable wall angle is obtained in a conical frustum with a varying wall angle fabricated using Single Point Incremental Forming (SPIF). The test material was 0.8-mm-thick Ti-6Al-4V titanium alloy sheets, and the test used a tungsten carbide tool with a rounded tip with a radius of 4 mm. Complete workpieces were heated using hot oil with a temperature of about 200 °C, and in addition, the high rotation speed of the forming tool generated an amount of friction heat. The input parameters were tool rotational speed, feed rate, step size, and tool rotation direction. Various oil pressures were used to improve both the accuracy of the components formed and the friction heating process. On the basis of calculations performed by means of the response surface methodology, split-plot I-optimal design responses were obtained by means of polynomial regression models. Models were fitted using REstricted Maximum Likelihood (REML), and p-values are derived using the Kenward–Roger approximation. Observation of the fracture surface of Ti-6Al-4V drawpieces showed that the destruction is as a result of ductile fracture mode. Tool rotational speed and step size are the most significant factors that affect the axial force, followed by feed rate. It was also found that step size is the most significant factor that affects the in-plane SPIF force.

Single-Point Incremental Forming of Titanium and Titanium Alloy Sheets.

Incremental sheet forming of titanium and its alloys has a significant role in modern manufacturing techniques because it allows for the production of high-quality products with complex shapes at low production costs. Stamping processes are a major contributor to plastic working techniques in industries such as automotive, aerospace and medicine. This article reviews the development of the single-point incremental forming (SPIF) technique in titanium and its alloys. Problems of a tribological and microstructural nature that make it difficult to obtain components with the desired geometric and shape accuracy are discussed. Great emphasis is placed on current trends in SPIF of difficult-to-form α-, α + β- and β-type titanium alloys. Potential uses of SPIF for forming products in various industries are also indicated, with a particular focus on medical applications. The conclusions of the review provide a structured guideline for scientists and practitioners working on incremental forming of titanium and titanium alloy sheets. One of the ways to increase the formability and minimize the springback of titanium alloys is to treat them at elevated temperatures. The main approaches developed for introducing temperature into a workpiece are friction heating, electrical heating and laser heating. The selection of an appropriate lubricant is a key aspect of the forming process of titanium and its alloys, which exhibit unfavorable tribological properties such as high adhesion and a tendency to adhesive wear. A review of the literature showed that there are insufficient investigations into the synergistic effect of rotational speed and tool rotation direction on the surface roughness of workpieces.

Simulation and experimental investigation of multi-walled carbon nanotubes/aluminum composite fabrication using friction stir processing

Multi-walled carbon nanotube/aluminum composites are fabricated on Al–Si cast alloy employing friction stir processing. First, the microstructure of the stir zone, as well as the effect of process parameters on the size of silicon particles, is investigated. Then, the process is numerically simulated using a thermo-mechanically coupled three-dimensional finite element method model. Material flow, as the primary reason for the dispersion of reinforcing particles, is considered in the numerical model, and proper conditions to obtain a uniform dispersion of multi-walled carbon nanotubes are determined. Scanning electron microscope analysis is carried out to consider the particle distribution in the texture of the stir zone. The results show that the particle distribution improves significantly by changing the tool rotation direction between the friction stir processing passes. The hardness test is accomplished on the cross-section of the friction stir processed specimens, and finally, the wear test is performed to compare the wear resistance of the composites with the base alloy. The results show that the wear resistance and hardness of the produced composites are considerably enhanced compared to the base alloy.

Effect of Process Parameters on Mechanical Properties of Aluminum Composite Foam Developed by Friction Stir Processing

The underwater friction stir processing is used for development of aluminum metal matrix composite (AA2219-Y2O3) foam. For development of foam, holes with different diameter in the mid thickness of plate were filled with a mixture of TiH2 and aluminum powder and underwater friction stir processing was used to mix this mixture in aluminum metal matrix composite. Then precursors extracted from the processed zone and heated upto 650°C in a furnace for development of foam. The effect of diameter of hole, number of passes and the tool rotation direction has been studied on the foam cell size and static and dynamic compressive behavior of the foam. It is found that as the diameter of hole increases, the size of pores increases. The distribution of pores is better with higher number of passes and increasing the hole diameter. The quality of foam further improves by reversing the tool rotation direction. The developed foam has different pore size varies from 0.7 to 2.7 mm depends on the FSP parameters. Based on the size of pores and their distribution the relative density ranges from 0.1 to 0.78. The foam produced with 4 mm hole diameter has best static and dynamic compression properties.

Defects, microstructure and mechanical behaviour upon multi-pass friction stir processing of magnesium alloy with spiral tool path

Friction stir processing is an advance technique to modify the microstructure of metals for enhanced mechanical properties. Previous works have demonstrated that the friction stir processing of Mg alloys is feasible. These works are restricted to small areas or sample sizes. The objective of this work is to adopt spiral tool path strategy to process a complete blank of Mg alloy and study the effect of process parameters on the microstructure and hardness. The friction stir processed samples are prepared with different combinations of tool shoulder overlaps and tool rotation directions. Experimental results show fully consolidated processed Mg blanks are achieved with the tool rotation direction, which forces the advancing side towards the ‘yet to be processed’ side of the tool. Further, tool rotation direction plays a crucial role towards defect formation and retention upon friction stir processing of Mg alloy blanks with spiral tool path. The microstructural studies and hardness test are performed for the fully consolidated processed blanks. The microstructure of the processed region consists of refined grains, with banded regions comprising even finer grains. The friction stir processing of the as-cast Mg alloy also lead to the dissolution of second phase and more uniform distribution of the alloying elements in the Mg matrix. The grain refinement and second phase dissolution lead to enhanced hardness upon friction stir processing. Higher tool shoulder overlap promotes higher temperatures and plastic deformation, which leads to more grain refinement and second phase dissolution with corresponding increase in hardness levels. The local variation in average hardness within a processed sample corresponds well to the local variation of the average grain size. This work shows that large samples of Mg alloy can be friction stir processed towards microstructure modification and mechanical property enhancement, with appropriate combination of tool rotation direction and tool shoulder overlap.

Artificial intelligent approach for process parameters modeling of friction stir processing

In the current study, an ANFIS model has been created using FSP process boundaries to predict the UTS & Hardness of Al-Y 2 O 3 composite. This work involved modelling, experiment, and optimization of FSP process parameters. For optimization and prediction process has been finished by four input variables such as: traverse speed, spindle rotary speed, no of passes and tool rotation direction. Total 36 experiments were carried to determine the UTS and hardness with different input parameters combination and all data sets that is 216 rules sets were applied to prediction, testing, and optimization of mentioned UTS & hardness by the help of Adaptive Neuro Fuzzy Inference (ANFIS). The results showed that the traverse speed had been 90 mm/min, the spindle rotating speed seemed to be 970 RPM, the multi-no-passes and the CCLW spindle rotation direction given the maximum hardness and UTS. Afterwards one confirmation test was executed to verify the ANFIS optimization solution.

Features for friction stir welding of butt joints of casting VAL8 alloy with wrought 1565chN2 and AMg6M alloys

The results of technological features for friction stir welding of butt joints of sheet blanks with thickness of 3 mm made of casting aluminum V AL8 alloy with wrought magnalium group 1565chN2 and AMg6M alloys are presented. It is established that the time resistance of the joints depends on the location of the welded alloys relative to the direction of tool rotation during friction stir welding. The ultimate strength of welded joints of VAL8 alloy with 1565chN2 and AMg6 alloys in automatic argon-arc welding is 0.82...0.84 of the ultimate tensile strength of VAL8 alloy. The grain size in the stir zone practically does not depend on the initial grain size in the alloys to be joined. The destruction of the joints made of VAL8 + 1565chH2 alloys under cyclic loading has multi-focal character and is initiated from irregularities on the surface of the weld. The discrete nature of the change in the chemical composition of the weld metal along the axis of the weld is revealed. The weld is formed by alternating strips of connected alloys with width of 30...90 microns.

Microstructure evolution and mechanical properties of double-sided friction stir welding between AA6061-T6 and AA7075-T651

The present study appraises the effect of tool rotation direction during dissimilar double-sided friction stir welding of AA6061–AA7075 thick plates. The mechanical strength, fracture behavior and the microstructure evolution for the joints are studied. Sound joints without defect and higher strength was achieved for the joint wherein tool rotation in the second weld is provided in the reverse to that of the first weld. Electron backscatter diffraction of welded joints revealed finer grains at the weld center than observed below the tool shoulder affiliated to high degree of deformation/strain. Pole figures revealed the dominance of high shear texture B/B¯ and C components at the weld center. Orientation distribution function revealed the presence of strong intensity recrystallization texture components Cube {001}<100>, Goss {110}<001> and P {011}<112> at the weld center.

Optimization of FSW Parameters to Improve the Mechanical and Metallurgical Properties of Aluminium Alloy AA 5083 Joints

Friction Stir Welding (FSW) is carried out on armour grade AA5083 aluminium alloy having the dimensions of 100X75X6.35 mm. The FSW process and tool parameters play a major role in deciding the joint strength. Many processing conditions and material properties affect the microstructure evolution and mechanical behaviours of the produced joints. Various parameters such as welding speed, tilt angle, spindle speed and various tool profile are used. Analyzing the mechanical behaviours of joints welded like tensile strength and hardness were investigated. The tool rotation and welding direction same side are similar is called Advancing side (AS) and opposite on the other known as retreating side (RS). The input process parameters which influence the strength of the joints. Main consideration is to select the best parameter to produce the defect free joints. Experiment is designed to determine the major factors affecting the hardness and tensile strength of the joints. Effect of rotational speed, welding speed and tilt angle on tensile strength and hardness are studied. The contribution of each factor is determined from ANOVA analysis “Tensile strength and hardness increased with increasing the rotational speed 1000 rpm to 1400 rpm, traverse speed from 30 mm/min to 40mm/min”. This investigation mainly deals with Taguchi and ANOVA were performed to improve the effective characteristics of welding inputs.

Temperature prediction of ultrasonic vibration-assisted milling

Machining temperature is a key factor in ultrasonic vibration-assisted milling as it can significantly influence tool wear rate and residual thermal stresses. In current study, a physics-based analytical predictive model on machining temperature in ultrasonic vibration-assisted milling is proposed, without resorting to iterative numerical simulations. As the tool periodically loses contact with the workpiece under vibration, three types of tool-workpiece separation criteria are first examined based on the tool trajectory under ultrasonic vibration. Type I criterion examines whether the relative velocity between tool and workpiece in cutting direction is opposite to the tool rotation direction. Type II criterion examines whether the instantaneous vibration displacement in radial direction is larger than instantaneous uncut chip thickness. Type III criterion examines whether there is overlap between current and previous tool paths due to vibration. If no contact, the instantaneous temperature rise is zero. Otherwise, the temperature rise is predicted under shearing heat source in shear zone and secondary rubbing heat source along machined surface. A mirror heat source method is applied to predict temperature rise, considering oblique band heat sources moving in a semi-infinite medium. The proposed predictive temperature model in ultrasonic vibration-assisted milling is validated through comparison to experimental measurements on Al 6063 alloy. The proposed predictive model is able to match the measured temperature with high accuracy of 1.85% average error and 5.22% largest error among all cases. Sensitivity analysis is also conducted to study the influences of cutting and vibration parameters on temperature. The proposed model is valuable in terms of providing an accurate and reliable reference for the prediction of temperature in ultrasonic vibration-assisted milling.

Friction stir welding of butt joints of 1420T1 and 1163T alloys sheets

The results of the butt joint formation of 5 mm thickness sheets from 1420T1 and 1163T aluminium alloys in different combination are presented. It is established that the ultimate strength of the joints depends on the location of the welded alloys relative to the direction of the tool rotation during friction stir welding. It is shown that depending on the location of 1420T1 and 1163T alloys on the side of the run in or out of the tool, the maximum temperature at the edge of the tool shoulder is 385 or 410 °C, in the weld core the metal is heated to 490 °C. The stir zone (the weld metal) consists of two zones corresponding to welded alloys without stir with each other. Ultimate strength to welded joint 1420T1 and 1163T alloys is 0.65...0.73 of ultimate strength to the 1420T1 alloy

Properties–microstructure relationship in Al–Fe in situ composite produced by friction stir processing

Effects of Fe particle volume percent (from 0 to 5%) and changing the tool rotation direction in each pass were studied on the microstructure evolution and mechanical properties of the in situ Al/intermetallic composites produced by three passes friction stir processing (FSP) with ∼10 µm Fe particles. Optical and scanning electron microscopes were used for the investigation of the composite homogeneity, formation of Al–Fe intermetallic compounds, and fracture surfaces. Tensile and microhardness tests were also carried out to evaluate the mechanical properties of the composites. Solid-state reactions between the aluminum matrix and Fe particles led to in situ formation of Al3Fe and Al5Fe2 intermetallics in the composite. Changing the tool rotation direction in each pass reduced asymmetrical distribution of the reinforcing particles and resulted in better dispersion of Fe particles. Increase in the particle volume percent refined the composite average grain size from ∼35 μm in the sample processed without particles to ∼6 μm in the composite included 5 vol.% of the Fe particles. Zener limiting grain size relationship was used to estimate the volume fraction of the sub-micron particles in the composites. Enhancement of the reinforcing particle volume percent (to 5%) increased ultimate tensile strength and yield strength of the composite up to ∼60% and ∼95%, respectively, due to finer grain structure as well as the higher load-bearing capacity of the Fe and intermetallic reinforcing particles compared to the aluminum matrix. Contributions of the Hall–Petch effect and the other strengthening mechanisms in the yield strength of the composites were also investigated.

Effect of reverse material flow on the microstructure and performance of friction stir welded T-joints of an Al-Mg alloy

Friction stir welding (FSW) has been developed and commercially applied with success to connect large and complex structures. However, process optimization is still required to improve the mechanical performance of the T assemblies. Therefore, a second welding pass was applied in this work and was performed backwards, while maintaining the same tool rotation direction. Thus, due to the creation of a reverse material flow, a second advance side over the previously retreating side of the joint was formed, which significantly reduced the defects typically found in FSWed T-joints. The joints were manufactured with dissimilar Al–Mg alloys (AA5083), which is of particular interest to the shipbuilding sector. The microstructural analysis revealed that the second pass significantly reduced the kissing bonding defect on the joints retreating side. As a result, the mechanical properties were improved under quasi-static loading, reaching performance levels comparable to those of the base material. A digital image correlation system (DIC) linked to a tensile test system was used to investigate the local strain fields of the T-joints under two different loading conditions. The fatigue strength was also evaluated and the FSWed T-joints reached the fatigue keen with a nominal load range of 88.4 MPa under skin loading.

Effects of the relative tool rotation direction on formability during the incremental forming of titanium sheets

The effects of tool rotation direction during single point incremental forming of pure titanium were experimentally studied. Axisymmetric components with a varying wall angle were formed using a round-tipped tool of 10 mm diameter and following a 3D spiral tool path. Test runs were executed by changing one factor at a time. Spindle rotation was tested in both the climb and the conventional directions. Tool step depth between runs was increased by a fixed interval over the range of 0.35 mm up to the plate thickness of 0.8 mm. The experimental results obtained by a comparison between the two forming strategies and their impact on the characteristics of formability are discussed in this paper. The achieved level of the forming angle (75°), and the reduction in geometric deviations from the conventional strategy, presents interesting findings. Considerable variations in the trends of forces and temperature between the two forming strategies are presented and discussed.

Effect of overlap orientation on fatigue behavior in friction stir linear welds of magnesium alloy sheets

In this work, we investigate the effect of sheet stacking orientation on fatigue behavior in friction stir linear welding of AZ31Mg alloy. It is well known that during friction stir welding, the advancing and retreating flow of the material generated by the tool creates asymmetrical weld features resulting is anisotropic mechanical behavior. As such, friction stir welding of overlap joints was carried out on 2mm thick sheets, where the orientation of the pull direction of the coupon was varied with respect to the tool rotation direction. Subsequently experimental fatigue tests were performed to evaluate this effect of the sheet stacking orientation on cyclic behavior. The fatigue results showed that the overlap joints loaded on the retreating side exhibited superior performance compared to the advancing side. Post-mortem analysis coupled with finite element results suggest that the geometrical shape of the faying surface produced by the advancing and retreating material flow largely determines the number of cycles to failure in these friction stir linear welded overlap joints.