Powder Coating

At a Glance

Applicable Materials

Colors

Texture

Can be applied with

Black (20% or 90% gloss)
White (20% or 90% gloss)
Gloss or semi-gloss
Media blasting, tumbling (neither is needed)

About the Process

Powder coating is a process in which a dry powder paint (either a thermoplastic or thermoset polymer) is applied to a metal surface using electrostatic application. Unlike traditional liquid paint, powder coating does not need a solvent to keep the binder and filler of the paint in liquid suspension. This allows for application of thicker coatings without running or sagging, and the coatings are also tougher as a result.

The powder coating process starts off by electrically grounding the part to be painted, which gives it a net negative charge. After grounding, the paint is sprayed at the part using a corona gun, which applies a positive charge to the powder. The polarization of the two components causes the powder to stick to the metal, where it will remain so long as it is undisturbed.

After the powder has reached a specified thickness on the part, it is cured into a polymeric film using elevated temperatures (~200°C), such as with a convection oven. Thermosetting polymers will crosslink during the curing process to improve performance, but thermoplastic varieties simply flow while heated to form the final coating.

CNC finishing powder coating semi gloss
CNC finishing powder coating high gloss

Design Considerations

- This process adds substantial thickness to a part’s surface, so plugging and masking threaded/reamed holes or other critical-to-function surfaces is recommended.
- Powder coating polymers are usually insulative and offer poor electrical conductivity.

Related Resources

Finishing Metal Parts Glossary