GM corrosion engineer Christa Cooper inspects a Cruze body shell for rust. Image: © GM Corp.Enlarge Photo
You can learn a lot by tearing a car down to its individual components, especially if that car has been force-aged to simulate years of life in the harshest possible environment. By applying forensic science to the automotive world, GM is doing just that with the new 2012 Chevrolet Cruze.
Rust is generally the enemy of steel, and rust can form anytime bare steel meets water and oxygen. Add salt, like many states use to de-ice roads in winter weather, and the process of corrosion can accelerate greatly.
In the past, automakers lacked the tools to effectively force-age cars, and rustproofing was generally done by the car dealer or the aftermarket, with marginal results. Today, General Motors has the ability to simulate 10 years of hard life, in the worst possible conditions, within a few months.
In the case of the 2012 Chevy Cruze, cars were tested to the 95th percentile, representing the worst-case environment that GM can simulate. Next, the cars were stripped down to individual components to search for rust, a process that involved drilling out up to 3,000 spot welds by hand.
When traces of rust were found, steps were taken to eliminate moisture or treat steel in affected areas. In the case of the Cruze, forensic engineers found corrosion where the inner panel of the rear door meets the safety beam. The forensic team made suggestions to change to a rust-resistant steel stamping, and the corrosion was eliminated in future tests.
Tearing down a car can take a two-member forensic team as long as two weeks, but the benefits in added body life are payback for their efforts. As corrosion engineer Christa Cooper puts it, “it’s part investigation, part engineering - I love this job.”