Structural parts such as threaded plates create highly stable connections in the vehicle. For their production, the forming specialist Kauth uses partly unique know-how – and BALINIT® FORMERA. The CrAlN-based coating from Oerlikon Balzers catapulted the service life of a forming tool from a few hundred to over 60,000 finished parts.
The Kauth Group knows exactly how different structural components can be connected to one another with high strength - thanks to the unique tube technology developed in the 1970s with a large automobile manufacturer, which is still a unique selling point of the company with its headquarters in Denkingen. A tube is a thread passage, produced by step-by-step deep-drawing in combination with stamping of a sheet of steel using progressive dies. Unlike nuts welded onto sheet metal, the part manufactured in this way is made in one piece, with no weak points and the associated risks of breakage or corrosion. On this basis, Kauth manufactures threaded plates, hinge systems, attachments for axles, seats, engines and transmissions as well as brackets for tank and exhaust systems for many well-known car manufacturers.
Withstands 9 tons
The stability elements produced can be welded onto a wide range of body components. They not only serve to fasten other parts, they increase safety where high forces are at work. "Built into the suspension of the rear wheel axle, for example, our parts can take over 9 tons of load," describes Johannes Kauth, managing director with his brother Christian. The high stability is achieved through strain hardening of the machined metal during forming. Strip material made of steel is first stretched in width, then in height and then compressed again to form the tube. In the case of the threaded plates, this is done in a 1,000-ton press with a tool made of powder-metallurgical high-speed steel (HSS) manufactured by Kauth.
If a tool is exposed to such forces, even copious amounts of lubricating oil will not protect against damage. "After a few hundred strokes, it's over, the wear is too great, which is why we only work with coated tools," explains Tobias Wenzel, Head of Tool Maintenance. To this end, Kauth has been cooperating with the coating partner Oerlikon Balzers for over ten years.
Test winner BALINIT® FORMERA
In the case of threaded plate production, a CrAlN-based layer clearly came out on top in various tests: BALINIT® FORMERA. This PVD coating (Physical Vapor Deposition) is used for metal forming of high-strength steels and scores with an almost unrivaled wear behavior, a layer thickness of around 10 micrometers and a special surface finish that reduces friction.
In order to increase the service life to more than 60,000 manufactured parts, the punch of the modular tool is coated with BALINIT® FORMERA. "We can change such wear parts quickly, and the long availability of the coated tool ensures little machine downtime. That pays off,” explains Tobias Wenzel. Not only in view of the annual volume of around 7 million pieces for this thread plate project alone. Coatings generally mean more process reliability for the entire business, the important basis of which is an in-house tool shop.
Kauth is a technology leader and can produce extremely solid tubes, thicken material at critical points or draw sheet steel up to 80 millimeters. Competences that only a few companies have mastered and that are also needed in electromobility: battery technology tends to make vehicles heavier there, which means that more and more stability and strength of structural parts are required. In this respect, Kauth already offers solutions for the future - always with the support of suitable coatings.
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