The automotive division of Hetal-Werke, located in Alpirsbach (Germany), is intensively looking for alternatives to conventional joint technologies. In the future, ATP? TriPress fasteners from Arnold Umformtechnik are expected to be used in place of conventional weld-on studs. These press-in studs match the requirements profile of the company, which specialises in the full scope of kinematic subassemblies and hinges in the passenger car seating area.

"The anticipated use of lighter materials, such as magnesium, fibre-reinforced composites such as carbon, or high-strength steel in car construction requires fastener systems that ideally provide better joint quality at lower cost," according to Reinhard Gruber, sales manager of the automotive division of Alpirsbach-based Hetal-Werke (Figure 1). With their triangular shape, Arnold TriPress press-in studs provide the answer to this cost/benefit dilemma. They are polygonal fast-assembly components that can be pressed into plastic and light metal materials (Figure 2).

The cost savings result from the process. 

The number of manufacturing operations is dramatically reduced compared to the welded-stud option, and cycle times are shortened. The triangular shank and longitudinal knurling provide high resistance to fastener stripping in permanent joints, such as for seat rail adapters (Figure 3). Circumferential locking grooves on the shank provide high pull-out strength.Eliminating the thermal stresses resulting from stud welding reduces the effort necessary for material inspections, which yields cost savings of around 50 per cent for this cost item alone. The environmental impact, such as noise and vapour emissions, is also reduced, along with the associated protective measures. In addition, the reject rate in production is sustainably lower due to the purely mechanical nature of the process.

Experience from the use of ATP? TriPress fasteners indicates potential cost savings of around 80 per cent compared with using weld-on studs. At the same time, joint quality is improved and the process allows different types of materials to be assembled quickly and economically. These are all convincing arguments for the specialists at Hetal-Werke.

Arnold Umformtechnik GmbH & Co KG, Germany. Tel: +49 (0)160/98908602. Fax: +49 (0)7947/821-195. Email: michael.pult@arnold-umformtechnik.de