Tech Update

Tailor-welded coils bring tailor-welded blank (TWB) benefits to progressive-die and roll-formed parts. Weight and cost savings along with part consolidation are the forces driving this new technology.

Leading the way in North America is TWB Co., LLC, Monroe, MI, and we asked the firm’s manager of new product development Mark Eisenmenger to summarize the company’s work in this area. What follows is a brief summary of a paper Mark prepared for Great Designs in Steel 2010, held May 5 in Livonia, MI.

There are 18 common TWB applications in the automotive body-in-white, but more than 35 applications have been identified for tailor-welded coils—technology developed in Germany and based on technology that evolved for high-volume blank-welding applications. TWB Co. has completed several design and feasibility studies that illustrate potential applications for the North American market and the impact this technology will make on automotive steel-body structures

several additional parts scheduled for implementation in the next several years. Tailor-welded coils are implemented much the same way that tailor-welded blanks have been implemented over the past 25 years, and may have more potential due to the number of coil-fed press and forming processes used in metal fabrication. Using conventional and advanced high-strength steels, tailor-welded coils offer weight and cost savings by utilizing the exact gauge and grade of steel that the finished part requires. Sheet thickness can range from 0.4 to 3.5 mm, with weld length to 4 m.

Another major benefit of using tailor-welded steel products is the ability to consolidate parts into single stamped components that improve dimensional characteristics, lower weight and provide a significant cost savings. Many automotive applications realize as much as a 25-percent cost savings and at the same time provide a lower-weight finished part. A German manufacturer, for example, uses tailored coils to stamp a longitudinal chassis beam, which reduces vehicle weight by 2.0 lb. And, one recent design study shows a 25-kG weight savings by using tailor-welded coils to optimize 33 progressive-die parts for material grade and thickness.

The coil-welding systems used to manufacture tailor-welded coils actually evolved from blank-welding machines—slit coils are fed into TWB Co.’s continuous welding machines. The welded coils then are recoiled for customer use. Typical automotive parts that run in a progressive die and benefit from a tailor-welded steel coil include roof bows, B-pillar inners, sills and rails. Nonautomotive appliance brackets and construction supports also have also been identified and planned for future implementation.

TWB Company LLC: 734/289-6471, www.twbcompany.com