Fluidized-bed coating: cost-effective and efficient

Requiring minimal tooling, the technique achieves layer thicknesses of 250 to 500 micrometers; even layers of one to two millimeters are possible. In this process, heated steel production parts of any shape are dipped for a few seconds in fluidized VESTOSINT^® powder. The powder sinters to the surface of the piece and fuses into a smooth surface, thanks to its residual heat.

A fluidized-bed coating pan consists of the powder container and the air receiver, separated by a porous fluidizing bottom. Oil- and dust-free air flows into the air receiver and passes through the fluidizing bottom in the form of fine bubbles. It transforms the sintering powder to a fluidized state, which resembles a boiling liquid. The fluidized-bed coating powder has a particle size distribution ranging from 30 to 250 microns, and is adjusted so as not to produce dust. Depending on the desired coating thickness, the pieces are heated to 230–450°C and dipped for 2–10 seconds.

The process works without solvent. Materials that change their shape, lose their properties or generate gases during the above-described procedure cannot be coated.

Key applications for fluidized-bed coating with VESTOSINT^® include the coating of

• Wire products of all kinds (e.g., dishwasher racks and refrigerator shelves)
• Industrial components (e.g., springs, rollers, drive shafts, valve handles, handrails)