Analysis of the oscillation behavior during ultrasonic welding of EN AW-1070 wire strands and EN CW004A terminals

For fulfilling the demand of durable yet lightweight electrical connections in transportation industries, ultrasonic metal welding (USMW) sees widespread use in these branches. As the ultrasound oscillations utilized in the welding procedure occur at a range of only a few micrometers at frequencies of 20–100 kHz for an overall duration of only 50–1500 ms, it is not possible to observe the compaction behavior with the bare eye. This paper focusses on investigating the oscillation behavior of the horn, the anvil, and the joining partners during the welding procedure by utilizing an array of synchronized laser vibrometers and performing welds with incrementing time stages. The oscillation data is correlated with temperature measurements in the welding zone as well as tensile testing results. Inter alia the formation of sidebands at the fundamental frequency as well as 2nd- and 3rd-order harmonics has been observed for the anvil, terminal, and wire front face when exceeding optimal weld time which would lead to maximum joint strength. Following the assumption of other research groups, the cause of these sidebands could be a change in relative motion of these components. As the terminal is slipping with increasing weld time, it could be assumed that the reason for the sidebands is low-frequency movement of the anvil, modulated onto the fundamental frequency, additionally indicating successful bonding of the stranded wire and the terminal. Furthermore, this slipping of the terminal on the anvil could lead to increased wear of the anvil knurls.

Process Monitoring in Ultrasonic Metal Welding of Lithium Batteries by Power Signals

Ultrasonic metal welding is one of the key technologies in manufacturing lithium batteries, and the welding quality directly determines the battery performance. Therefore, an online welding process monitoring system is critical in identifying abnormal welding processes, detecting defects, and improving battery quality. Traditionally, the peak welding power is used to indicate abnormal process signals in welding process monitoring systems. However, since various factors have complex impacts on the electric power signals of ultrasonic welding processes, the peak power is inadequate to detect different types of welding defects. Therefore, a signal pattern matching method is proposed in this study, which is based on the electric power signal during the entire welding process and thus is capable of identifying abnormal welding processes in various conditions. The proposed method adopts isometric transformation and homogenization as signal pretreatment methods, and Euclidean distance is used to calculate the similarity metric for signal matching. The effectiveness and robustness of the proposed method are experimentally validated under different abnormal welding conditions.

Simulation of an Electric Arc in Metal Welding

This paper describes the proces of electric arc welding in the zone of protective gas, with an emphasis on transmitting metal dropelts via a short ciruit.Parameters of the welding proces and of an electric arc are described, and a mathemacal model for the MIG system is sugessted. Model simulation is completed used Matlab/Simulink package. The proces is simulated using real parameters in order for the output values of the process to corespond to real values obtained by the means of mesasurement.

A Parametric Study on Dissimilar Metal Welding of Aluminum and Copper using Pulsed Fiber Laser

Joining dissimilar metals is critically challenging due to the difference in properties of the metals themselves which leads to the formation of brittle intermetallic compounds (IMCs). Aluminum (Al) and copper (Cu) are well-known materials for electrical application as they attribute to various advantageous characteristics. In lithium-ion batteries, to obtain most of the features of the metals, combinations of these metals are highly recommended. However, with such high reflective metals and heat-sensitive characteristics in the battery, the joint of these metals needs to be processed with an advanced method. In this study, a pulsed fiber laser source that suits to process for heat-sensitive components is utilized to weld two overlap configurations of Al/Cu and Cu/Al, separately. Different ranges of laser power are designated for each welding configuration separately. Thus, the quality of the two welds is evaluated in terms of microstructure and mechanical properties. Consequently, it is found that the growth of IMCs with dendritic structure towards the Al side is observed in both cases. Moreover, the weld of Al/Cu shows a better connection strength as well as fewer imperfections than the weld of Cu/Al.

Dissimilar Non-Ferrous Metal Welding: An Insight on Experimental and Numerical Analysis

In recent years Gas Metal Arc Welding (GMAW) technology has expanded its functionalities in various areas which have further motivated its usage in several emerging manufacturing industries. There are several issues and challenges associated with this technology, especially in dissimilar metal welding (DMW). One of the predominant challenges is selecting appropriate welding parameters which influence the efficiency of this technology. To explore several modern advancements in this expertise, this paper has done an exclusive survey on various standards of GMAW and its variants for selecting suitable parameters for welding dissimilar nonferrous metals. This review summarizes various experimental and numerical results along with related illustrations to highlight the feasibility of welding dissimilar nonferrous metals using traditional GMAW and investigations on advanced GMAW processes such as cold metal transfer (CMT) and pulsed GMAW (P-GMAW). Simulation and modeling of nonferrous DMW have identified several research gaps and modeling problems. Researchers and manufacturers can use this review as a guideline to choose appropriate welding parameters to implement GMAW and its variants for non-ferrous dissimilar welding. It found that by controlling the heat input and effective post-heat treatments, adequate joint properties can be achieved. Automated large -scale manufacturing will widen the utilization scope of GMAW and avoid some costly methods such as laser welding, ultrasonic welding, and friction stir welding etc.