U.S. automakers use more zinc in fight against rust

The use of zinc-coated steel in the typical U.S.-produced automobile rose 23.2% during the 1986 model year, according to the New York based Zinc Institute.

That’s the largest annual per- vehicle increase in the use of zinc as a corrosion inhibitor.

As auto makers further improve the no-rust-through warranties on their products, they built an average of 8.34 lb of zinc into each of their 1986 cars in the form of pre- coated steel compared to 6.77 lb in the previous model year.

The record 1.57-lb gain was derived from design data provided to the institute by General Motors, Ford, Chrysler and American Motors. The figures take into account three commonly used types of zinc-coated steel.

The weight of zinc die castings in the typical 1986 U.S.-built car, however, settled at 19.7 lbs — a 0.7-lb decline from the 1985 model year. The 3.4% decline in die casting is largely due to the trend away from carburetors in favor of fuel injection.

Six years ago, in 1980, a total of 25 lb of zinc die castings were used in American-built cars.

The 23% increase in the zinc coatings content of 1986 cars represents the sharpest upturn ever recorded in a market that has been steadily expanding in recent years. In 1985, the per-vehicle use of zinc was up 8.7% while a 12.9% increase was registered during the 1984 model year and a 2.1% increase was recorded in 1983.

Since the stamping of steel results in a 35% waste factor, the gross amount of zinc used in pre- coated steel totalled 12.83 lb for the average 1986 model. About one pound of zinc in the form of zinc- rich paint was also applied in the cause of corrosion protection pushing the domestic car consumption total to 13.83 lbsper typical unit compared to 11.41 lb in 1985.

In an 8-million-car year at the current per vehicle average, the U.S. domestic automotive market would account for over 55,000 tons of zinc consumed for coatings of all types. The institute predicts that the potential market can increase by another 40,000 tons.