Jan
2
Chrysler delays coatings for panels
Filed Under Chrysler News
DETROIT–Material qualification problems are preventing Chrysler Corp. from meeting its goal of converting the exterior body panels on most or all of its cars to two-side precoated steel during the 1987 model year, it has been learned.
Instead of trying to phase this material into use on its vehicles during the current model run, Chrysler is resetting its target date to mid-1989, sources said.
Chrysler officials and the company’s suppliers have not talked about the problems publicly, but the automaker has decided to change its coating requirements and target dates for achieving advanced levels of corrosion-resistance in its vehicles.
The new specifications call for electrodeposited zinc-iron (Zn-Fe) alloy coatings to be deposited in a “50/50″ mix consisting of 50 grams per square meter on both sides of the steel used in the firm’s body skins instead of a differential coating mix of 50/25-50 grams on the inside and only 25 grams on the outside. The iron content in the coatings will continue to be 15 percent and Chrysler will continue to rely on just two suppliers, National Steel Corp. and USX Corp., to furnish nearly all of the precoated steel.
The decision to raise the coating requirements was made in part to solve the problem of what to do with the differentially coated steel when nicks, scratches or small dents are created in the surface, sources said. In contrast to the case when each side has the same 50-gram density, differentially coated panels can’t be simply turned over if the damage occurs on a surface intended to be visible because the coating weight on that side does not meet Chrysler’s requirements for the inside surface.
By or before the middle of 1989 the company hopes to have the body skins of all of its cars converted to two-side 50/50 precoated steel. The only panels that stand to be excluded from this are the roofs, which are subject to considerably less corrosion than are fenders, doors, rocker panels, quarter pan panels and other body components.
The company probably will be able to convert the exterior body panels of most of its vehicles, including pickup trucks, vans and wagons, to the two-side Zn-Fe precoated material by mid-1989.
Chrysler, which has led the campaign in this country to develop cars that have an advanced degree of built-in corrosion resistance, did not anticipate any slow-to-resolve problems trying to get two-side, differentially coated steel into high-volume use in its cars (AMM/MN, Feb. 13). But the steelmakers are employing their new electrogalvanizing lines to produce this material, and the new technology has posed some problems on both the suppliers’ and user’s sides.
When these lines were designed, it was thought they would be used to apply pure zinc coating (Zn-Zn), rather than alloy coatings, to the steel sheet, or coils. Chrysler’s two steel suppliers have had to learn how to use their new facilities to apply Zn-Fe coatings of consistent quality, while Chrysler has had to learn how to handle, form, weld and paint the alloy-coated steel. For both, the learning process has been more difficult than anticipated.
