Electrospinning can be used to create nanofiber mats for diverse applications, from wound dressings and tissue engineering to filters for medical and biotechnological applications. In most of these ...applications, it is necessary to fix the nanofiber mat on a macroscopic textile fabric, on another nanofiber mat or within a frame to keep it at the desired position. Due to their extremely low thickness and areal mass, however, nanofiber mats are easily destroyed by sewing, and in several situations glued bonds are too thick and not flexible enough. Here we report on ultrasonic welding of polyacrylonitrile nanofiber mats, suggesting this method as a joining process without destruction of the mat morphology for thermoplastic nanofiber mats. A variety of welding patterns results in different adhesion forces between both joined nanofiber mats and different failure mechanisms, with some welding patterns enabling bonding stronger than the mats themselves. Our findings show that ultrasonic welding is a possible joining method for polyacrylonitrile nanofiber mats.
The paper presents a new method for determining the machine-hand welding times of synthetic polymer materials using ultrasonic welding machines with rotary sonotrode. The method is based on the ...claims and observations of W. Möller intended for the clothing industry in the 1990s, according to which there is a spontaneous drop in sewing speed when strongly curved seams are joined, which is due to the possibility of human reactions. The method for determining machine-hand sewing times of curved seams was well accepted in garment production processes. It is used to standardize production time. Using ultrasonic welding machines with rotary sonotrode, the problem of determining the time of ultrasonic joining of curved seams on clothing or technical textiles remained unsolved. That is why is completely new and original model was created, which combines eight technical parameters of ultrasonic welds, eight technological parameters of the production process and seven ergonomic parameters depending on the psychophysical conditions of the workers. The systematic development of the mathematical relationship of all 23 parameters mentioned and the corresponding mathematical expressions for determining and calculating these parameters are presented. These results were also verified by experimental measurements, which show a favourable correlation between the calculated and measured machine hand times. The relationships between the recommended welding speeds, the critical radii of curvature and the number of reactions required according to Möller and the new model are also presented. An analysis of the success in the application of Möller’s and the new model was also performed.
There have been extensive efforts within the field of lightweight design over the past decade, especially regarding multi-material designs. It has also become a major subject for electrical ...applications, especially considering electrical contacts in modern vehicles and the respective approaches of substituting copper by aluminium. In this case, ultrasonic metal welding (USMW) represents a well-suited technology to join resultant material combinations. The joint formation is usually completed within less than 1 s and is based on frictional heating and plastic deformation at the interface and within the work pieces but is also highly affected by the boundary conditions at the interface. Therefore, this investigation focusses on the influence of the interface characteristics during USMW of EN AW 1070-stranded wire to Ni-plated EN CW004A terminals, especially considering different platings. The samples are characterised by shear tensile testing as well as metallographical preparation. In addition, the fabricated samples are subjected to elevated temperature in order to draw a comparison of the ageing behaviour for the different interface conditions. The results underline the need for a profound understanding of the mechanisms at the interface and that the bond quality can differ significantly depending on the process parameters.
In this book, you will find information on new materials and new welding technologies. Problems related to the welding of difficult-to-weld materials are considered and solved. The latest welding ...technologies and processes are presented. This book provides an opportunity to learn about the latest trends and developments in the welding industry. Enjoy reading.
Aluminum/copper dissimilar joints are widely used in electronics, the automobile industry, and battery manufacturing. Ultrasonic spot welding (USW), as a quality, efficient, clean, and ...low-consumption solid phase bonding (SPB) technology, is applicable for the connections of aluminum/copper and other highly conductive and heat-conducting materials. At present, this technique has been applied by automobile producers and lithium battery manufacturers at home and abroad. In this work, the optimal performance of the ultrasonic welding process of aluminum/copper dissimilar joints was studied. Based on a single-factor test on how welding parameters (lap mode, welding pressure, welding amplitude, and welding energy) influence the quality of welding joints, the lap mode of aluminum plates on the top and copper plates on the bottom (Al/Cu) was deemed better than that of copper plates on the top and aluminum plates on the bottom (Cu/Al) under the same optimal parameters (40 psi, 45 μm, and 500 J). With this group of parameters, the Al/Cu joint formed a cladding mechanical occlusion. The element had a diffusion layer of 2 μm and a joint specimen maximum failure load of 605 N.
We present an all-polymer, single-use microfluidic chip system produced by injection moulding and bonded by ultrasonic welding. Both techniques are compatible with low-cost industrial ...mass-production. The chip is produced for magnetic bead-based solid-phase extraction facilitated by immiscible phase filtration and features passive liquid filling and magnetic bead manipulation using an external magnet. In this work, we determine the system compatibility with various surfactants. Moreover, we quantify the volume of liquid co-transported with magnetic bead clusters from Milli-Q water or a lysis-binding buffer for nucleic acid extraction (0.1 (v/v)% Triton X-100 in 5M guanidine hydrochloride). A linear relationship was found between the liquid carry-over and mass of magnetic beads used. Interestingly, similar average carry-overs of 1.74(8)nL/µg and 1.72(14)nL/µg were found for Milli-Q water and lysis-binding buffer, respectively.
•We present an all-polymer mass producible passive filled microfluidic chip system.•Rapid system fabrication is obtained by injection moulding and ultrasonic welding.•The system is made for single-use nucleic acid extraction using magnetic beads.•We systematically map compatibility of the chip system with various surfactants.•We quantify the volume carry-over of magnetic beads in water and 0.1% triton-X solution.
Ultrasonic welding has been applied for joining thermoplastic components due to their advantages such as clean, fast and reliable. The basic principle is to use the mechanical energy of ultrasonic ...frequency vibration to produce the molten pool at the interface of the joined components under high pressure to create solid-state welding joints. Depending on the specific application, the ultrasonic horn is designed to generate suitable amplitudes on the surface of the welding zone. Uniformity of the amplitudes can be a challenge as the welding area increases. Therefore, design a welding horn in order to obtain the uniform amplitudes at the large area is significant difficult. This work presents a method for obtaining the uniform amplitudes at the working surface of the stepped wide-blade horn. Finite element method is used to analyze the amplitude distribution at the horn surface of 250 × 34 mm2 with working frequency of 15 kHz and aluminum alloy 7075. The uniformity of amplitude is obtained by changing the shape of the horn.
The market for hybrid electric vehicles and electric vehicles is expected to expand due to the recent growing interest in environmental protection and stricter regulations. The power supply system ...used for them tends to increase, and the size of electric wires used is increasing. The use of aluminum wires is advancing as a measure to reduce weight to improve fuel economy. The destruction of the oxide film on the aluminum surface is important for the connection between the aluminum wire and the terminal, and it is considered that ultrasonic bonding is effective particularly for the connection between the large－sized aluminum wire and the terminal. In this study, we investigated the correlation between contact resistance and welding strength, which are important for connecting wires and terminals. As a result, good contact resistance was obtained with a welding strength of about 1/20 of the maximum welding strength, and even if the weld strength was increased, the contact resistance was constant.
This paper focuses on the development of an effective methodology to determine the optimum welding conditions that maximize the strength of joints produced by ultrasonic welding using response ...surface methodology (RSM) coupled with genetic algorithm (GA). RSM is utilized to create an efficient analytical model for welding strength in terms of welding parameters namely pressure, weld time, and amplitude. Experiments were conducted as per central composite design of experiments for spot and seam welding of 0.3- and 0.4-mm-thick Al specimens. An effective second-order response surface model is developed utilizing experimental measurements. Response surface model is further interfaced with GA to optimize the welding conditions for desired weld strength. Optimum welding conditions produced from GA are verified with experimental results and are found to be in good agreement.
PC/ABS thermoplastic blends are widely employed in manufacturing sectors, as it yields good mechanical behavior when subjected to dynamic loading conditions. While investigating the fundamental ...nature of PC/ABS blends, ultrasonic welding process appears to suit their joining as compared to other conventional techniques. This paper focuses on PC/ABS welding using ultrasonic and the subsequent investigation from the insight of thermal science. It is imperative for the materials to retain key properties after subjecting it to welding. Examinations to evaluate these properties through DSC reveal a lower onset temperature change and a small variation of glass transition temperature, respectively, for parts which indicate minimal changes in thermal properties in welded and non-welded specimens. Apparent activation energies determined from TG data are practically independent of heating rates, which suggests that the most important process in the degradation of these materials corresponds to ABS. Those mixtures with high PC content show a clear increase in apparent activation energies with heating rate, suggesting that the thermal degradation mechanism of these samples is composed of several complex processes, each predominant during different stages of the overall process. SEM is used to investigate the structural morphology of the welded parts.
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