Extrusion Welding Research Articles

Effect of Preheating Parameters on Extrusion Welding of High-Density Polyethylene Materials.

High-density polyethylene (HDPE) has emerged as a promising alternative to fiber-reinforced plastic (FRP) for small vessel manufacturing due to its durability, chemical resistance, lightweight properties, and recyclability. However, while thermoplastic polymers like HDPE have been extensively used in gas and water pipelines, their application in large, complex marine structures remains underexplored, particularly in terms of joining methods. Existing techniques, such as ultrasonic welding, laser welding, and friction stir welding, are unsuitable for large-scale HDPE components, where extrusion welding is more viable. This study focuses on evaluating the impact of key process parameters, such as the preheating temperature, hot air movement speed, and nozzle distance, on the welding performance of HDPE. By analyzing the influence of these variables on heat distribution during the extrusion welding process, we aim to conduct basic research to derive optimal conditions for achieving strong and reliable joints. The results highlight the critical importance of a uniform temperature distribution in preventing defects such as excessive melting or thermal degradation, which could compromise weld integrity. This research provides valuable insights into improving HDPE joining techniques, contributing to its broader adoption in the marine and manufacturing industries.

Long-term performance of HDPE extrusion welds aged at 85°C in synthetic leachate

The effect of ageing at 85°C of extrusion welds of 1.5 mm-thick high-density polyethylene (HDPE) geomembrane, immersed in synthetic municipal solid waste leachate, is investigated with respect to its standard oxidative induction time (Std-OIT) and stress crack resistance (SCR). Results show that the heat-affected zones (HAZ) adjacent to the squeeze-out bead (flashing) may exhibit faster STD-OIT depletion than the sheet. Generally, individual weld SCR failure times were observed to be between that of the notched and unnotched sheet. Welds with high welding-induced geometric irregularities (WIGI), and overheated fusion and extrusion welds are shown to result in SCR failure times close to that of a notched sheet. The average time to nominal failure (taken to be when tNF = 250 h) of Cool and Good welding parameter combinations ranges between 3% and 15% shorter than the unnotched sheet. Differences in tNF were attributed to accelerated craze formation in welds with high WIGI from stress concentration. No significant difference was observed between the SCR values of fusion and extrusion welds during 40 months of immersion in MSW-L3. This paper shows that overgrind negatively impacts the SCR of welds and accelerates the degradation of SCR.

Numerical and experimental investigations on AA6063 extrudates: effect of number of portholes on extrusion load and weld strength

In aluminium extrusion process, metal flow is greatly controlled by the die geometry and a variety of intricate profiles can be achieved by designing dies of different configurations. In porthole die extrusion, number of portholes used for a profile is often determined by the subjective knowledge of designers. Nevertheless, extrusion load and weld strength of profile produced are not only dependent on extrusion ratio, temperature of deformation but also on the number of portholes along with other die geometry variables. In the present investigation, systematic studies were carried out on three different dies with four ports, three and two ports around die center to extrude profiles of outer diameter 29.4 mm and thickness 2 mm. Numerical simulations were carried out for estimation of pressure, temperature, strain, and strain rate parameters in the weld chamber for all the dies, followed by press trials and profiles produced were subjected to wedge expansion test. The results from numerical simulations indicated that pressure generated inside weld chamber increases with number of portholes. The surface plots indicated highest pressure of about 280 MPa for four port hole and about 276 MPa for three ports die and pressure of about 160 MPa was estimated for two port hole die at the entry of weld chamber , which is 65 mm from profile end. Similarly, temperature at profile exit was 551 °C for four portholes die and 546 °C for three portholes die and 537 °C for two portholes die. Furthermore, press trials indicated peak extrusion loads of 5241 kN, 4406 kN and 3961 kN respectively for four, three and two portholes die. Thus, the peak extrusion load decreased by about 16% for three port and about 25% for two ports die in comparison with four port die. Also, the extruded profiles in wedge expansion test indicated mean compression load of 22.70 ± 0.14 kN in four porthole die, mean compression load 22.29 ± 0.26 kN for three port die and mean compression load of 17.841 ± 0.27 kN.

Effect of welding parameters on properties of HDPE geomembrane extrusion welds

The stress crack resistance (SCR) of high-density polyethylene (HDPE) geomembrane extrusion welds is examined for a 1.5 mm HDPE geomembrane and three different welding parameter combinations (denoted as “Cool”, “Good”, and “Overheated”). Results are reported for unnotched welds, unnotched sheet, and notched sheet. The average SCR for a Good extrusion weld is 23% of that of the unnotched sheet SCR. Little variation is found between the three welding parameter combinations for low geometry irregularity SCR weld specimens. There is no statistically significant difference between a good-quality fusion and extrusion weld. However, operator-dependent weld induced geometric irregularity (WIGI) greatly affects the SCR of extrusion welds. Extrusion welds with high WIGI have an average unnotched SCR of only 9% of the unnotched sheet. Extrusion welds with an overground surface can have an unnotched SCR as little as 1% of the best extrusion weld. Deleterious weld bead geometries are identified to provide a framework with which engineers can identify “high-risk” extrusion welds with respect to stress cracking.

Steady melting in material extrusion additive manufacturing

PurposeA main cause of defects within material extrusion (MatEx) additive manufacturing is the nonisothermal condition in the hot end, which causes inconsistent extrusion and polymer welding. This paper aims to validate a custom hot end design intended to heat the thermoplastic to form a melt prior to the nozzle and to reduce variability in melt temperature. A full 3D temperature verification methodology for hot ends is also presented.Design/methodology/approachInfrared (IR) thermography of steady-state extrusion for varying volumetric flow rates, hot end temperature setpoints and nozzle orifice diameters provides data for model validation. A finite-element model is used to predict the temperature of the extrudate. Model tuning demonstrates the effects of different model assumptions on the simulated melt temperature.FindingsThe experimental results show that the measured temperature and variance are functions of volumetric flow rate, temperature setpoint and the nozzle orifice diameter. Convection to the surrounding air is a primary heat transfer mechanism. The custom hot end brings the melt to its setpoint temperature prior to entering the nozzle.Originality/valueThis work provides a full set of steady-state IR thermography data for various parameter settings. It also provides insight into the performance of a custom hot end designed to improve the robustness of melting in MatEx. Finally, it proposes a strategy for modeling such systems that incorporates the metal components and the air around the system.

Numerical analysis of tooling design for extruding wide aluminium hollow profiles using multi-container extrusion technology

Recently a novel multi-container extrusion method has been proposed and proved feasible to simultaneously extrude multiple billets for producing thin-walled wide profiles with reduced force by experiments. Due to its different die structure compared to conventional extrusion methods, the effects of tooling geometries on the multi-container extrusion performance should be comprehensively analysed as the base of die design optimisation. In this study, the original three-container extrusion design and six modified designs were established to investigate the influence of three key geometrical variables, including container diameter, upper die height and welding chamber height, on the extrusion performance through finite element simulation. The considered extrusion performances include metal flow uniformity, extrusion force, welding pressure, die lifetime and material yield. The drawbacks of the original die design were revealed after the primary analysis of the key influencing variables and a three-step way of design improvement was proposed accordingly. Container block and upper die were optimised for the first step; welding chamber height and die bearing length were modified during the second and third steps respectively. Compared with the original design, the final optimised design can decrease the unevenness of the extrudate front shape by 75% and double the material yield, while the extrusion force, die lifetime and welding quality were basically unchanged.

Effects of Zn, Mg, and Cu Content on the Properties and Microstructure of Extrusion-Welded Al-Zn-Mg-Cu Alloys.

The study presents the results of research on the influence of different contents of main alloying additions, such as Mg (2 ÷ 2.5 wt.%), Cu (1.2 ÷ 1.9 wt.%), and Zn (5.5 ÷ 8 wt.%), on the strength properties and plasticity of selected Al-Zn-Mg-Cu alloys extruded on a bridge die. The test material variants were based on the EN AW-7075 alloy. The research specimens, in the form of 100 mm extrusion billets obtained with the DC casting method, were homogenized and extrusion welded during direct extrusion on a 5 MN horizontal press. A 60 × 6 mm die cross-section was used, with one bridge arranged in a way to extrude a flat bar with a weld along its entire length. The obtained materials in the F and T6 tempers were characterized in terms of their strength properties, hardness, and microstructure, using EBSD and SEM. The extrusion welding process did not significantly affect the properties of the tested materials; the measured differences in the yield strength and tensile strength between the materials, with and without the welding seam, were up to ±5%, regardless of chemical composition. A decrease in plasticity was observed with an increase in the content of the alloying elements. The highest strength properties in the T6 temper were achieved for the alloy with the highest content of alloying elements (10.47 wt.%), both welded and solid. Significant differences in the microstructure between the welded and solid material in the T6 temper were observed.

FEM Numerical and Experimental Work on Extrusion Welding of 7021 Aluminum Alloy.

Extrusion welding of AlZnMg alloys encounters great technological difficulties in practice associated with high shaping forces and the low quality of longitudinal welds. Three different chemical compositions of 7021 aluminum alloy, differing in terms of Zn and Mg contents, were used in the first stage of the research. The laboratory device modelling the behavior of metal in welding chambers of the porthole die was applied to examine the ability of 7021 alloys to produce high-quality joints. The weldability tests were carried out for different welding temperatures-400, 450 and 500 °C-and for a fixed welding pressure of 300 MPa. The microstructural effects in pressure-welds were evaluated with the use of OM and SEM/EDS. The temperature-pressure parameters in the welding chambers were analyzed by using the FEM method for original porthole dies while extruding tubes with dimensions of Ø50 × 2 mm. Finally, the industrial extrusion trials were performed with examination of the structure and strength of the seam welds. It was found that it is possible to produce high-quality high-strength welds in tubes extruded from AlZnMg alloys in industrial conditions (the strength of welds in the range of 96-101% of the strength of the basic non-welded material) through properly matched alloy chemical composition of the alloy, construction of the porthole dies and temperature-speed conditions of deformation.

Effects of Process Parameters on the Microstructure and Mechanical Properties of Large PE Pipe via Polymer Melt Jetting Stacking

The conventional methods for producing large-diameter pipes, such as extrusion and winding fusion welding, suffer from various drawbacks including difficulties in forming, complex molds, and high costs. Moreover, the flexibility and production efficiency of traditional manufacturing processes are relatively low. To address these challenges, this study proposes a new manufacturing process for polymer melt jetting and stacking based on fused deposition modeling (FDM) and rolling forming principles. This innovative approach aims to overcome the limitations of conventional methods and improve the flexibility and production efficiency in large-diameter pipe manufacturing. In the polymer melt jetting and stacking process, a plastic melt with a specific temperature and pressure is extruded by an extruder. The melt is then injected through the nozzle embedded in the previous layer of the pipe blank. By utilizing the localized rolling action of the forming device and adjusting the diameter using a diameter adjustment device, the newly injected plastic melt bonds with the previous layer of the pipe blank. Finally, the continuous large-diameter plastic pipe is formed through cooling and solidification. Experimental investigations demonstrate that the polymer melt jetting and stacking process can produce pipes with diameters ranging from 780 mm to 850 mm and thicknesses of 20 mm to 25 mm. The radial tensile strength, impact strength, and microstructural orientation of the produced pipes exhibit superior performance compared to those in the axial direction. Additionally, process parameters such as rolling speed, cooling temperature, melt extrusion speed, and tractive velocity significantly influence the microstructure and mechanical properties of the pipes.

Double Stage Friction Stir Spot Extrusion Welding: a Novel Manufacturing Technique for Joining Sheets

Double Stage Friction Stir Spot Extrusion Welding: a Novel Manufacturing Technique for Joining Sheets

Development of a multi-container extrusion method for extruding lightweight wide plates and sheets

Extrusion of wide plates and sheets of light alloys has been studied over a long period of time, yet the extrudable width of the material is still limited due to high extrusion force requirement. To overcome this drawback, a new multi-container extrusion process is proposed in the research, which allows the production of lightweight plates and sheets with less force compared to that of existing extrusion methods. A lab scale feasibility study system with three containers has been designed and built and tested for AA1060 billets. Experimental work has been carried out with the extrusion temperature of 450°C and extrusion speed of 0.5 mm/s. Optical microscopy observation and tensile tests have been performed for the extruded materials at different positions to investigate the extrusion welding quality between the three extrusion billets. The test results show that the welding quality improves as extrusion progresses and the overall welding quality is stable. This study demonstrates the feasibility of the new multi-container extrusion method.

An extrusion-welding criterion of magnesium alloy considering interfacial void shrinkage driven by plastic deformation and atomic diffusion

This study is aimed to develop a new criterion to predict the solid-state welding quality of magnesium alloy during the porthole die extrusion of hollow profiles. In this criterion, the mechanism of interfacial void shrinkage of magnesium alloy during the extrusion welding is considered, including the plastic deformation of rough interfaces and the atomic diffusion driven by the hydrostatic pressure gradient. The developed criterion is validated by the combined extrusion-welding experiments of magnesium alloy and the corresponding numerical simulations. The results indicate that the bonding strength of magnesium alloy increases with growing billet temperature and decreasing the extrusion stem speed. A sound weld seam with a strength higher than 316 MPa is formed by the porthole extrusion when the billet temperature of Mg-Al-Zn-RE alloy is above 350 °C (623 K) and the extrusion speed is below 16.67 mm/s. Compared with other existing criteria, the developed criterion is more reliable in predicting the extrusion-welding quality of magnesium alloy.

Welding analysis and optimization of ultra- sonic welding in HDPE-5%PBI composite by CODAS decision-making approach

Engineering plastics are increasingly being used in structural and non-structural applications. As the need for plastics grows, so do the joining requirements. Ultrasonic welding is one of the favoured processes for polymer composites among numerous approaches, especially for bonding plates, automotive panel boards and couplings due to its joint quality and low cost. The High-density polyethylene (HDPE) matrix was reinforced with 5 wt% of polybenzimidazole (PBI) fibre by twin screw extrusion process and welding samples were prepared using injection moulding. In this study, Ultrasonic welding was used to connect 4 mm-thick lapped HDPE-5wt% PBI composites. Taguchi-based L27 orthogonal array was employed for experiments to study the lateral shear strength (LSS) and Shore-D-Hardness for the input parameters (i) weld duration (30,45 and 60 ms), (ii) frequency (19,20 and 21 Hz) and (iii) horn pressure (1.5, 2 and 2.5 MPa). The relevance of the parameters affecting shear strength and hardness of weld was studied using analysis of variance (ANOVA). ANOVA results shows the frequency (Hz) and weld time (ms) had contributed 32.4% and 31.6% in determining shear strength and weld time (ms) contributes 45% for shore D hardness. The ultrasonic welding process was carried out, and the multi-criteria decision-making (MCDM) approach was used to optimise the process parameters. From CODAS assessment the relative evaluation score of 2.444 was achieved by the twenty fifth experiment having the input parameters (IP) at 60 ms welding time, frequency of 21 Hz and pressure at 2.5 MPa considering each output factor with an entropy of 0.5. Fractography and weld morphology of welded joints were investigated using scanning electron microscope (SEM).

Расчет мостовых конструкций из алюминиевых сплавов на выносливость

Introduction. The author has developed a method for the fatigue resistance analysis of bridge structures made of aluminum alloys subjected to polycyclic loading. The author suggests that this method should be introduced into the currently enhanced regulatory documentation focused on the analysis of highway bridges made of aluminum alloys. Materials and methods. The method is based on the results of integrated laboratory testing of a number of aluminum alloys 1915T, AD35 T1, 1565hM, EN AW-6082 T6 that have good prospects in terms of the production of bridge structures. Physical-mechanical and fatigue characteristics were identified in the course of the static testing of specimens of these alloys before the fatigue cracking at different values of the cycle asymmetry coefficient. The theoretical fundamentals of the method stem from the domestic research on the fatigue resistance analysis of steel structures and foreign regulatory materials on the fatigue resistance analysis of bridge structures made of aluminum alloys. Results. The reliability of the new method was verified in the course of static and fatigue testing of a full-scale pedestrian bridge made of 1915T alloy and orthotropic plates made of EN AW-6082 T6 alloy, designed by NRU MGSU and manufactured by the Russian plants GS-Reserve, KraMZ and Sespel using advanced innovative technologies of extrusion and friction stir welding. Discrepancies between the experimental findings and the results of the analysis, made pursuant to the proposed methodology, are within 5–20 %. Conclusions. The proposed method can also be applied to other types of structures made of aluminum alloys, such as tanks, pipelines, high-rise structures, and other items that are subject to multiple cyclic effects.

Applying torque based control to Friction Stir Extrusion

A series of Friction Stir Extrusion welds with varying groove geometries were performed to determine the effect on processing forces. A clear correlation with groove geometry was observed for z-force, torque, and y-force. The data was used to design a torque-based plunge depth controller. All the welds from the prior series of welds were repeated with the controller applied. When comparing the controlled welds to the uncontrolled welds, the use of the controller eliminated surface defects at larger groove cross-sectional areas, and the controlled welds maintained 10 % of the reference torque. The controller demonstrated good transient performance for both a step and continuous linear increasing groove widths.

Self-bending extrusion welding behavior of streamlined function die

Self-bending extrusion welding behavior of streamlined function die

Investigation into Atomic Diffusion at the Interface During Extrusion Welding of Magnesium and Magnesium Alloys

Investigation into Atomic Diffusion at the Interface During Extrusion Welding of Magnesium and Magnesium Alloys

Study of the microstructure, bonding evolution and mechanical properties of continuously extruded magnesium AZ31 sheet

Magnesium (Mg) alloys have considerable potential for lightweight applications in many industrial sectors. However, developing a cost-effective sheet forming process is extremely challenging because its poor formability leads to severe edge cracking, which limits their extensive applications. To overcome this challenge, scholars proposed a continuous extrusion extending forming (CEEF) method to produce Mg alloy sheets through solid-state extrusion welding of two rods. An AZ31 Mg sheet (160 mm width and 8 mm thickness) was produced through CEEF. The microstructure, texture and properties of the formed AZ31 Mg alloy sheet were investigated using experimental and finite element simulation. The high deformation strain (≥200%) and the high temperature in the welding region led to good welding quality. Banded microstructures and numerous tensile twins were found in the welding region and might result from <c+a> non-basal slip and rotational dynamic recrystallisation. The (0001) basal poles were inclined approximately 45° with respect to extrusion direction (ED) at the entrance of the chamber. No cracks occurred in the welding regions of the transverse direction (TD) samples. The tensile strength of the welding region was comparable with that of the feedstock area. The largest elongation of 18.6% versus 20% of the feedstock materials was observed in the samples along the extrusion direction. The high tensile strength of the welding region was attributed to the large number of tensile twins.

Influence of material degradation on weld seam quality in hot gas butt welding of polyamides

The joining of plastics is required because component geometries are severely restricted in conventional manufacturing processes such as injection molding or extrusion. In addition to established processes such as hot plate welding, infrared welding, or vibration welding, hot gas butt welding is becoming more and more important industrially due to its advantages. The main benefits are the contactless heating process, the suitability for glass fiber reinforced, and high-temperature plastics as well as complex component geometries. However, various degradation phenomena can occur during the heating process used for economic reasons, due to the presence of oxygen in the air and to the high gas temperatures. In addition, the current patent situation suggests that welding with an oxidizing gas is not permissible depending on the material. On the other hand, however, there is experience from extrusion welding, with which long-term resistant weld seams can be produced using air. Investigations have shown that the same weld seam properties can be achieved with polypropylene using either air or nitrogen as the process gas. Experimental investigations have now been carried out on the suitability of different gases with regard to the weld seam quality when welding polyamides, which are generally regarded as more prone to oxidation. The results show that weld strengths are higher when nitrogen is used as process gas. However, equal weld strengths can be achieved with air and nitrogen when the material contains heat stabilizers.

Homogenization of 7075 and 7049 Aluminium Alloys Intended for Extrusion Welding

During the extrusion of aluminum alloys profiles using porthole dies, the temperature of the material in the welding chamber is one of crucial parameters determining the quality of longitudinal welds. In order to extend the permissible temperature range, the billets intended for this process should be characterized by the maximum attainable solidus temperature. Within the present work, the homogenization of AlZnMgCu alloys DC-cast (Direct Chill-cast) billets was investigated, with the aim of solidus temperature maximization. Conditions of soaking and cooling stages were analyzed. The materials were homogenized in laboratory conditions, and the microstructural effects were evaluated on the basis of DSC (Differential Scanning Calorimetry) tests and SEM/EDS (Scanning Electron Microscopy/Energy-Dispersive Spectroscopy) investigations. For all examined alloys, the unequilibrium low-melting microstructure components were dissolved during soaking, which led to the significant solidus temperature increase, in comparison to the as-cast state. The values within the range of 525–548 °C were obtained. In the case of alloy with highest Cu concentration, the application of two-step soaking was necessary. In order to take advantage of the high solidus temperature obtained after soaking, the cooling rate from homogenization must be controlled, and the effective cooling manner is strongly dependent on alloy composition. For high-Cu alloy, the solidus decreased, despite the fast cooling and the careful billets preheating being necessary.