GM Process for Better Brakes

General Motors is using a process ordinarily used in powertrain component manufacturing to produce better brake rotors. Rotors that aren’t as susceptible to rust.

The process is ferritic nitro-carburizing (FNC). According to Jim Webster, GM brake rotor technical expert, after machining, brake rotors are put inside an oven that’s at 560°C and has a nitrogen-rich atmosphere. The rotors remain in the oven for 24 hours.

As a result, there is a layer measuring 0.01mm that provides corrosion-resistance to the brake rotors.

Not only do some wheel designs expose more of the rotor and calipers so that having a shiny non-rusted surface an aesthetic issue, but as Webster points out, there are performance issues that FNC improves, as well.

General Motors brake engineer Jim Webster with machined brake rotors in Flint, Michigan. (Photo by Jeffrey Sauger for General Motors)

When rust builds on rotors, there is a thickness variation that results in pulsations during braking, as well as some steering shudder. “Rotors aren’t a cheap think to replace. So doubling the average life expectancy of the brake rotors from 40,000 to 80,000 miles is something we think our customers will appreciate,” Webster says.

The FNC-processed rotors are presently in use on the Buick Lacrosse and Regal, and the Chevrolet Malibu, Impala and Volt models. The company plans to use FNC on more than 80% of its U.S. vehicles by model year 2016.

GM has patents pending on FNC.