Induction heat treat brake discs against corrosion.

Finishing in style

What do more and more leading auto makers (including BMW, Audi and Volvo) have in common? They’ve all selected EFD Induction to heat treat brake discs against corrosion.

Safety is of course a top priority for carmakers. Which is why they coat brake discs to prevent corrosion. Coating with Geomet—one of the world’s leading coating products— ensures top-level protection, especially in salty atmospheres. But as we’ll see, post-coating induction drying and curing finishes the job in style.

The process works like this. Once the discs have been coated, a conveyer transfers them to the induction heating booth where induction dries and cures them. 

The discs’ first stop is the induction drying stations, where the heat will range from 80–100°C. The number of stations depends on the  weight and shape of the discs, as well as the induction coil shape, and the stations are usually equipped with SINAC PM 50 converters   (50 kW each). Each station has a matching box consisting of capacitors, transformer and coil that is mounted on a double-axis moving table. That way, the coil is well-positioned for each brake disc. (Drying is basically a mass transfer process whereby water moisture or moisture from another solvent is evaporated.)

After drying, the discs move to the induction curing stations, where temperatures reach around 340°C. The number of stations here also depends on the discs’ weight and shape, as well as the coil shape, and each station has a SINAC PM 100 converter (100 kW). Curing  refers to the toughening or hardening of polymer material by cross-linking polymer chains. It can be achieved by chemical additives, ultraviolet radiation, electron beams, or, in this case, heat.

Well-known benefits

One coil can process all the discs on a production line. However, because all kinds of discs are included on the line, coil efficiency compromises must be made.

Also, disc temperature varies during the process. To overcome this, “free stations” between the stations create a more homogenous temperature.

Each heating station’s power is controlled separately in relation to the brake disc to be heated, and the MF frequency used on the existing installations is 7–12 kHz. Once cooled in a cooling chamber, the discs are placed on an exit conveyor for unloading.

Throughout, induction heating delivers well-known benefits: optimized consistency, maximum productivity, extended product life, minimal environmental impact, and reduced energy consumption.

Ultimately, applying heat induction to brake disc drying and curing illustrates once more how induction saves time and money. It also underlines how EFD Induction plays a role in making our roads safer—for everyone who uses them.