Ultrasonic Welding Method Research Articles

Investigating laser and ultrasonic welding of pouch cell multi-foil current collectors for electric vehicle battery fabrication

The escalating necessity for more efficient and defect-free joining of ‘ultra-thin foil collectors-to-tabs’ in electric vehicle (EV) Li-ion pouch cells motivates this study. The prevalent ultrasonic welding (USW) method for these joint types, faces limitations such as design constraints and access requirements, laser welding (LW) emerges as a promising alternative offering flexibility, one-side access and faster speeds with efficient heat input. This study aims to investigate the feasibility of LW as a viable alternative to USW for joining current collectors-to-tab joints. It compares the mechanical, metallurgical, electrical and thermal analysis of the joints to evaluate both welding techniques for joint defects. The comparison of solid-state material mixing during USW and the intermixing of aluminium (Al) and copper (Cu) during fusion LW using EDX analysis presents interesting observations in the study. The USW generates a thin transition layer with intermetallic compounds (IMCs) attributed to the diffusion of Cu into the Al matrix during joining, which is comparatively lower as in the case of LW with higher material mixing with brittle IMCs like Al2Cu and Al4Cu9. However, the joint strength of LW is comparatively lower than the USW joint attributed to the reduced fusion zone area. Furthermore, from the electrical contact resistance and the joint temperature analysis, it was found that the resistance and temperature vary by as much as 13% and 6%, respectively, for the 50 A and 75 A passing currents when the USW is replaced with the LW process.

Comparative Performance Evaluation of Ultrasonic Welding and Conventional Sewing Methods in Knitted Fabrics

Abstract When transforming two-dimensional fabric pieces into three-dimensional clothing with different sewing methods, choosing the proper technique is one of the primary factors affecting the quality of the product. Within the scope of the study, five different types of knitted fabric alternatives, which are frequently used in products for daily use, are discussed. The conventional joining methods (lock stitch and overedge stitching) and ultrasonic welding were evaluated in terms of joint performance. All the evaluations made in terms of seam strength and seam efficiency showed that the overedge stitch is more performant in sewing knitted fabrics. One of the critical advantages of ultrasonic welding, the absence of the need for needle and thread and the absence of these costs, necessitated the evaluation of one more feature of the joining methods in the study. In this context, the energy consumption values of all the methods were evaluated. As a result, the energy consumption value of ultrasonic welding is approximately 1.3 times higher than overedge stitching and approximately 10.7 times higher than lockstitching.

An investigation on metallurgical features and joint characteristics of ultrasonic spot welded Al-Ni sheets

Several potential benefits in joining thin, dissimilar and highly conductive metals in a solid-state environment make ultrasonic welding (USW) a popular method for building Li-ion battery packs. The USW method is highly complex and relies on multiple factors. In this study, aluminum (AA1100) and nickel (UNS N02200) dissimilar sheets were ultrasonically welded using various process parameters. Plastic deformation, microstructural development, and the corresponding mechanical characteristics of the joints were evaluated qualitatively and quantitatively. The joint strength and critical intensity factor values seemed to rise until the welding duration of 0.3 s, following which there was a subsequent drop in their values. Based on the mechanical analysis, it is observed that the optimal condition records an amplitude of 68 µm, a weld time of 0.3 s, and a clamping pressure of 0.24 MPa. It showed that the joint performance was significantly impacted by the plastic deformation and microstructural changes at the weld region. On the Al side, substantial plastic deformation was observed, and it was primarily attributed to the sonotrode knurls’ penetration. The Al sheet’s thickness was reduced by more than 40%. The microhardness readings at the welding region experienced diminution due to the acoustic softening effect. The cross-section and fracture surfaces of the Al/Ni weld exhibited several distinct microstructural characteristics, such as atomic diffusion, crimped interface, dimple pattern, and swirl pattern flow. Additionally, the diffusion zone is also investigated using X-ray diffraction analysis. These observations offer valuable insights for enhancing weld quality and controlling the overall welding process.

Joint interface optimization of all-CFRTP composite honeycomb prepared by ultrasonic multi-spot welding

An all carbon fiber reinforced polyetheretherketone (CF/PEEK) composite honeycomb is prepared by the multi-spot ultrasonic welding in this work. The interfacial responses and flat compression failure behaviors of the honeycomb are firstly analyzed. It is found that ultrasonic welding has both positive and negative effects on honeycomb performance. High-frequency vibration results in fiber waviness, which is beneficial to elevating both the bending resistance of the joints and the compression strength of the honeycomb. However, melted EDs also lead to resin-rich areas at the interface. Based on the findings, the multiwall carbon nanotubes/PEEK (MWCNTs/PEEK) energy directors are developed, providing new insights on optimizing the properties of the interface. The experimental results indicate that the interfacial node tensile strength is enhanced by 400 % (1267 kPa) with the MWCNTs content increasing to 7.5 wt%, and the optimized CF/PEEK honeycomb shows more superior specific energy absorption and specific compressive strength than those of the commercial light-weight honeycombs. Moreover, the joint failure behaviors are investigated thoroughly. The addition of MWCNTs is found to induce fiber bridging between the cell walls and facilitate stress transfer through the joint interface. The optimized ultrasonic welding method provides a new opportunity for efficient and volume manufacturing of carbon fiber reinforced composite honeycombs without dimension limitation and large mold costs.

Plastik Birleştirme Yöntemleri: Ultrasonik ve Vibrasyon Kaynağı

Plastic welding is a common method for manufacturing parts that can’t be molded and has a complex geometry such as the part that has undercuts. The process is suitable for mass production, cheap and meets automotive requirements. The process helps the zero-emission target of the automotive industry, due to the biggest obstacle of the plastic use in this sector was the moldability of the complex geometries. Most of the engine parts such as thermostat, water pump etc. can’t be molded as one piece. These engine components are manufactured by helping the plastic welding and decrease the weight of the automobile, therefore, improving fuel efficiency. Plastic welding technology has become more important especially in electrical vehicles, because metal to plastic replacement has a significant role in decreasing the weight of the vehicle. Selecting the welding method according to the polymer properties and the geometry of parts are the most important factors for the application area. All of the welding methods are basically based on the remelting of the welding surfaces of the parts and the consolidation of them under the pressure. In this paper, the vibration welding and the ultrasonic welding methods have been inspected. The most effective parameters of both processes have been discussed and shown.

Ultrasonic Welding of PEEK Plates with CF Fabric Reinforcement-The Optimization of the Process by Neural Network Simulation.

The optimal mode for ultrasonic welding (USW) of the "PEEK-ED (PEEK)-prepreg (PEI impregnated CF fabric)-ED (PEEK)-PEEK" lap joint was determined by artificial neural network (ANN) simulation, based on the sample of the experimental data expanded with the expert data set. The experimental verification of the simulation results showed that mode 10 (t = 900 ms, P = 1.7 atm, τ = 2000 ms) ensured the high strength properties and preservation of the structural integrity of the carbon fiber fabric (CFF). Additionally, it showed that the "PEEK-CFF prepreg-PEEK" USW lap joint could be fabricated by the "multi-spot" USW method with the optimal mode 10, which can resist the load per cycle of 50 MPa (the bottom HCF level). The USW mode, determined by ANN simulation for the neat PEEK adherends, did not provide joining both particulate and laminated composite adherends with the CFF prepreg reinforcement. The USW lap joints could be formed when the USW durations (t) were significantly increased up to 1200 and 1600 ms, respectively. In this case, the elastic energy is transferred more efficiently to the welding zone through the upper adherend.

Статистические зависимости влияния времени воздействия ультразвука на прочность и другие параметры сварного соединения полипропилена

Polypropylene is one of the most popular thermoplastic materials used in industry. To produce goods from this material, the ultrasonic welding method is often used. However, despite a large number of scientific papers, the influence of some parameters of the ultrasonic welding mode on the strength characteristics of polypropylene joints remains unstudied. The paper presents the results of experimental studies of contact spot ultrasonic welding of plates 3 mm thick made of 01003-26 grade polypropylene. The authors considered the process of gradual penetration of the ultrasonic tool working face into polypropylene to a depth equal to the total thickness of the welded plates. Statistical dependences of the depth of the tool face penetration into the material and the force of material separation on the ultrasound exposure time are obtained. The influence of the depth of the ultrasonic tool working face penetration on the tearing force of welded specimens is determined. A significant increase in the tearing force from 150 to 400 N was found at the tool penetration depth of more than 3.5 mm due to an increase in the nominal area of mutual mixing of the material between the welded plates caused by the flow of molten material into the gap. The authors proposed a hypothesis about the flow of the molten material in the direction opposite to the direction of penetration of the working tool by forming traveling Rayleigh waves. However, its confirmation requires additional studies of the influence of the ultrasonic welding mode parameters and the size of the gap between the parts to be joined on the rate of the molten material flow into the gap.

Applicability of ultrasonic welding to Ag-stabilized REBCO CC joints and evaluation of their electromechanical properties

Manufacturing a single long-length rare-earth barium copper oxide (REBCO) coated conductor (CC) tape with uniform critical current (I c) is still a challenge; therefore, joining between multiple-length CC tapes is needed in the production of longer CC tapes for superconducting cables, coils, and magnets. Various joining techniques have been developed to achieve acceptably low joint resistance (R j) with no I c degradation and good electromechanical properties. The authors established ultrasonic welding (UW) and hybrid welding (HW) methods for joining Cu-stabilized CC tapes with different configurations. However, these methods have yet to be applied to Ag-stabilized CC tapes to produce compact joints and longer tapes during in-line production. This study used the UW and HW methods to fabricate Ag-stabilized CC joints to have low R j without I c degradation through a direct connection at the overlapped Ag layers between both CC tapes. Two CC tape samples with different thicknesses of ∼2 µm and ∼6 µm Ag stabilizers were supplied to produce UW and HW Ag-stabilized CC joints. These were compared with soldered CC joints fabricated by a mechanically controlled soldering method. In the case of UW, the design of experiment using the Taguchi method was used to systematically determine the optimized weld parameter combination that yields a lower R j without any I c degradation. This study is a systematic attempt to evaluate the applicability of UW for solid-state joining between thin Ag layers, unlike the conventional joining of thick Cu stabilizers. Moreover, the electromechanical properties of differently processed Ag-stabilized REBCO CC joints were evaluated using both lap-shear and double-bending tests. As a result, the optimum UW parameter combinations were obtained to achieve Ag-stabilized CC joints. However, some variations were probably due to the differences in the production batch and thickness of the Ag layers. The UW Ag-stabilized CC joints showed superior joint characteristics and electromechanical properties compared to soldered CC joints. Good solid-state bonding of the Ag layers was observed through microscopic observation of the cross-section at the joint region of the UW CC joint. The joint characteristics and electromechanical properties of the UW Ag-stabilized CC joints can be further improved using the HW method.

Study on the SPCC and CFRTP Hybrid Joint Performance Produced with Additional Nylon-6 Interlayer by Ultrasonic Plastic Welding

Due to the high degree of dissimilarity in physicochemical properties between metal and carbon fiber, it presents a tremendous challenge to join them directly. In this paper, cold rolled steel (SPCC) and carbon fiber reinforced thermoplastic (CFRTP) chopped sheet hybrid joints were produced with the addition of Nylon 6 (PA6) thermoplastic film as an intermediate layer by the ultrasonic plastic welding method. The effect of ultrasonic welding energy and preheating temperature on the hybrid joint microstructure and mechanical behavior was well investigated. The suitable joining parameters could obtain a strong joint by adding the PA6 film as an intermediate layer between the SPCC and bare carbon fibers. Microstructural analysis revealed that the interface joining condition between the PA6 film and the SPCC component is the primary reason for the joint strength. The crevices generated at the interface were eliminated when the preheating temperature arrived at 200 °C, and the joint strength thus significantly increased. The lap shear test results under quasi-static loading showed that the welding energy and preheating temperature synergistically affect the joint performances. At 240 °C, the joint strength value reached the maximum. Through the analysis of the microstructure morphology, mechanical performance, and the failure mechanism of the joint, the optimized joining process window for ultrasonic plastic welding of SPCC-CFRTP by adding an intermediate layer, was obtained.

Interface microstructure and mechanical properties of copper/304 stainless steel dissimilar joint assisted by Ni transition layer using ultrasonic additive manufacturing (UAM)

The copper/304 stainless steel joints with high strength are obtained by preparing nickel transition layer on the steel surface using ultrasonic additive manufacturing (UAM) and pulsed TIG welding method. The results show that the addition of the nickel intermediate layer achieves metallurgical isolation between copper and steel, inhibits the infiltration of copper into steel grain boundaries and reduces joint stress, resulting in the formation of hybrid joints including fusion brazing (copper-nickel) and diffusion welding (nickel-steel). The weld and the vicinity of the interface are mainly composed of Cu-Ni solid solution and Ni-rich phase. The wavy texture produced by UAM on the nickel surface can form mechanical interlock at the interface to improve the joint strength, and finally all joints fracture near the fusion line on the copper side.

State-of-the-Art Technologies in Piezoelectric Deformable Mirror Design

In this work, two advanced technologies were applied for manufacturing a bimorph wavefront corrector: laser ablation, to vaporize conductive silver coating from piezoceramic surface, and parallel-gap resistance microwelding, to provide a reliable electrical contact between the piezodisk surface silver electrodes and copper wires. A step-by-step guide for bimorph mirror production is presented, together with the ‘bottlenecks’. Optimization of the laser ablation technique was carried out using an Nd:YAG laser with an output power of 4 W and a frequency of 20 kHz. A comparison of the ultrasonic welding and parallel-gap resistance microwelding methods was performed. The tensile strength in the first case was in the range of 0.2…0.25 N for the system ‘copper wire–silver coating’. The use of resistance welding made it possible to increase the value of this parameter for the same contact pair by almost two times (0.45…0.5 N).

Ultrasonic welding of short carbon fiber reinforced PEEK with spherical surface anvils

Ultrasonic welding of carbon fiber reinforced thermoplastic (CFRTP) has attracted increased attentions from researchers in the automotive and aerospace industries. This paper proposes a novel ultrasonic welding method for focusing the welding energy at the desired location without using the energy director (ED). An anvil with a spherical surface is used in the welding system instead of a conventional flat anvil. Short carbon fiber reinforced polyether ether ketone (CF/PEEK) is employed as the research material. The effects of spherical radius and welding energy on the weld formation are investigated. The microstructure, tensile-shear property, and fracture characteristics of the joints are also analyzed. The results show that the using of a spherical surface anvil can effectively concentrates the welding energy and therefore, reduces the scattered welds.

Comparative Study Between Solid State Welding and Radiant Energy Welding Processes for Joining Metallic Glassy Ribbons

Amorphous alloys have emerged as an important class of advanced materials that own a combination of properties, such as mechanical strength, hardness, high elasticity modulus and a very good corrosion resistance. Since the number of amorphous structures alloys increased in the last decades, ways of joining such materials were studied in order to produce complex structures or increase their size. Thus, if this kind of complex products are obtained, it will diversify their applicability in multiple and various domains. For this research two ways of joining amorphous ribbons has been studied: solid state welding and radiant energy welding. For the radiant energy welding process, it was selected electron beam welding (EBW) method and for the solid-state welding process, ultrasonic welding (UW) method was chosen. Seeing that these methods have found applicability in industries, a comparative study was done in order to see which one offers the best outcome. Recently, in the last years, such products were embedded in a polymer matrix, creating thus, composite materials that have improved mechanical properties. This raised curiosity for major industries, such as aero-space, medical and automotive. Amorphous ribbons from Ni-Fe-Cr-Si-B and Al-Ni-Nd-Co alloy families were welded by EBW method, and Cu-Zr-Al amorphous ribbons were welded by the UW method. Microstructure characterization has been performed by SEM, EDX, XRD and DSC analyses.

Effect of ultrasonic welding process parameters on seam strength of PVC-coated hybrid textiles for weather protection

Using a lapped seam, PVC-coated hybrid textiles with uniform thickness were bonded by continuous ultrasonic welding and conventional joining method with the help of hot air tape welding technique for weather protection purposes. Three fundamental sewing parameters at two distinct levels and three primary welding parameters at three levels based on 6 and 12 mm welding widths were used. To consider the effect of welding and sewing parameters on seam strength, full factorial designs of experiments were designed, fabricated, and tested. The thermal behavior and possibility of chemical conversion in the welding zone under the influence of ultrasonic vibrations were examined. Variation in width of heat-affected zone of weld seam was measured. The seam strength of ultrasonic weld seam compared with that of conventional seams, and superior seam strength yielding parametric levels were assessed. The parametric influence of both joining techniques on seam quality and their tendencies in the relationship were analyzed statistically. The weld seam strength (1256.392 and 2116.93 N/50 mm) was optimized numerically and identified its trend with the variation of the weld seam. The discovered relationship led to the conclusion that the variation in the weld seam can be used to estimate the tensile strength of the weld seam through the developed effective numerical model as a non-destructive testing method, and its outcome was successful as a destructive testing method. The result shows that the ultrasonic weld seam provided a higher tensile strength ( > 75%) than the conventional seam for both evaluated welding widths and obtained statistically significant results.

A study on thermo-mechanical analysis of ultrasonically welded dissimilar alloys for automotive application

Abstract Ultrasonic spot welding (USW) method has the capability to produce highly efficient solid-state bonds in lightweight alloys with minimum power consumption. Unlike fusion welding techniques, this technique utilizes less energy and produces superb joint quality with refined grain structures and minimal intermetallic compounds (IMCs). This method has been receiving attention progressively in the material joining field because of its advantages like environmentally friendly, shorter weld time, and involvement of low temperature. Thus, these properties make this process suitable for welding of malleable thin metal sheets. During the USW process, it is noticed that the effect of intensive material contact increases when the weld progresses, and it leads to the frictional heating and plastic deformation phenomena. Subsequently, it results in the change of mechanical and microstructural characteristics at the weld zone. To reduce the forming load and static stress distribution from the welded samples, it is necessary to analyze the thermo-mechanical properties of ultrasonically welded joints. In the current study, various aspects of ultrasonic energy on material deformation and temperature variations are investigated using the finite element analysis (FEA). As a result, several types of features are noticed in the weld region with different forming morphologies. To further explore the effect of weld process parameters on the weld interface of this dynamic process, the strength and fracture in USW are also studied.

Research into the Textile-Based Signal Lines Made Using Ultrasonic Welding Technology

Abstract The article describes research into the transmission properties of textile signal lines (TSLs) made using ultrasonic welding technology. The presented TSLs are made from electroconductive, nickel coated, fabric strips welded between non-conducting textile layers. The article presents an analysis of the usability of the ultrasonic welding method for creating TSLs. This analysis shows that direct welding of an electroconductive path with the substrate increases its linear resistance, making it impossible to create a properly functioning line. This article presents an alternative method of creating the line using ultrasound welding technology.

Effects of Different Roller Profiles on the Microstructure and Peel Strength of the Ultrasonic Welding Joints of Nonwoven Fabrics

Nonwoven fabrics are widely used in the textile manufacturing industry due to their advanced characteristics, such as their soft, water-repellent, recycle, ecological, and resilient functions. Nowadays, one of the innovated technologies applied to bond nonwoven fabrics is the ultrasonic welding method, due to the advantages afforded by its clean, fast, and reliable approach. In this work, isotactic polypropylene (PP) nonwoven fabrics were bonded by a continuous ultrasonic welding process. In order to consider the influence of the roller on the formation of welding joints and their mechanical properties, different roller profiles were designed, fabricated, and tested. Eight types of roller profiles corresponding to No. 1–No. 8 in the experiments were divided into four groups. After bonding, the microstructure in a typical case (i.e., No. 1) was captured by scanning electron microscopy (SEM) to examine the formation of the welding joints. Additionally, the load and the peel strength of the welding joints of all eight roller profiles were analyzed. The results showed that no welding defects, such as cracks or blowholes, were visible in the melted zone. The load depended on the area ratio(s) of the welding area (S0) to the cycling area (S1). Furthermore, it was found out that the peel strength of the welding joints with brick structures were higher than the peel strength in the case of solid line structures.

Особенности процесса разогрева при ультразвуковой сварке изделий из поликарбоната в условиях независимого давления

This paper presents a mechanism of formation of a hard-to-weld polycarbonate joint by ultrasonic welding. The method utilizes internal and external friction occurring in the welded joint area on abutting surfaces due to shear vibrations of the end of the upper part relative to the lower part. A layer of the heated welded material is formed, localized by thickness, in which predominant absorption of the ultrasonic vibrations occurs, which allows one to obtain high-quality and durable welded joints without significant deformation due to the concentration of thermal energy in the welding zone. The effect of independent welding pressure on the strength of the welded joint of polycarbonate is considered. A new method of ultrasonic welding under the conditions of independent pressure is proposed. The method consists of dividing the static welding pressure into two components: the pressure of the acoustic contact in the zone of contact of the waveguide with the product, and the welding pressure that compresses the welded products, with the latter component being lower than the former. In order to obtain high-quality welded joints made of polycarbonate and to prevent displacement of the welded edges during the welding process relative to each other, a special preparation of the welded edges is developed, which allows one part to be moved vertically relative to the other during the welding process. It is established that the quality of welding depends on the speed of movement and the angle of cutting the edges.

Ultrasonic welding of polymer fi lms

The choice of the method of ultrasonic welding of polymer fi lms is substantiated, its advantages over other welding methods are noted.It is shown that the parameters determining the performance of seam ultrasonic welding process for polymer fi lms are the amplitude of the waveguide oscillations, the welding static pressure and the speed of welding with a fi xed gap on a rotating support roller with self-stabilization of the welding seam thickness.

RESEARCH OF FACTORS INFLUENCING THE PROCESS OF FORMATION OF WELDED MICROCONNECTIONS IN ELECTRONIC MODULES

The features of the formation of microconnections in electronic modules on an aluminum-polyimide basis by the method of ultrasonic welding, which allows to obtain reliable mounting joints of different thickness aluminum without preliminary removal of oxide films where the use of contact welding and soldering are practically difficult or impossible, are investigated. The influence of technological modes (power of an ultrasonic generator, oscillation amplitude of a welding tip (tool), welding force and welding time) on the reliability of mounting microconnections is considered