FastenersASIA November 2023

Industry news

Ultrasonic welding

Fastener manufacturer selected for demanding ultrasonic welding application German specialist machine maker

such as 20,000 vibrations per second. The high fatigue strength that Bumax screws offer is central to their ability to withstand a high number of cycles without fracture. All Bumax bolts are made with high quality European steel, and the advanced manufacturing processes result in further enhance- ment of the material’s fatigue-resistance properties. Fatigue fracture often begins with a stress concentration such as inclusions, slags or surface defects. The raw materials Bumax uses, together with the metallurgical processes and surface properties, ensure the fatigue strength. Bumax also uses rolled threads rather than cut threads, which further increases fatigue resistance. Bumax AB

by heat generated by friction when applying high-frequency ultrasonic vibrational energy. “Standard steel bolts simply cannot cope with the extreme pulling and bending forces of ultrasonic vibration, so we had to find a bolt that does,” said Stefan Mueller, head of R&D at Schunk Sonosystems. “Of all the screws we tested, only Bumax met all our needs. Not only are Bumax consistent in how they perform and do not break, they last the lifetime of the sonotrode without problem, are not creating abrasion dust on the screw head and do not require rust protection.” The Bumax DX 129 (duplex stainless steel) offers high tensile strengths of minimum 1,200 MPa and fatigue resistance properties. It can handle the extreme forces of ultrasonic welding,

Schunk Sonosystems has opted to use Bumax DX 129 screws for all of its ultrasonic welding flexure sonotrode products, to improve quality and reliability. The machines are mainly used in the automobile industry. Schunk Sonosystems develops and builds machines for ultrasonic metal welding. The machines include a sonotrode or welding tip that transfers vibrational energy to the workpiece. Up to two high-strength bolts are required to fix the sonotrode, which is subject to extreme levels of vibration due to the very high frequency used in ultrasonic welding. Ultrasonic welding is a solid-state welding process that uses ultrasonic vibrations to weld pieces of metal together. The metals are welded together

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November 2023

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