What is Faraday Cage and how to avoid it in powder coating?

Generally, when parts have internal corners or an odd geometry, due to how the electrostatics travel through the metal, the powder will not apply to these areas easily. This is called a Faraday Cage. Within these zones, the resistance to electrical forces is much greater than on all other surfaces. This results in areas of a surface that are left bare of powder, leave such areas vulnerable to corrosion.

So how can we avoid Faraday Cage Effect?

First, you need to check the grounding of the parts, powder coating equipments and operators.  to ensure the powder particles could be attracted to the grounded surface.

Then, there should be a good charge of powder. If you do not have enough powder coming out of the gun itself, it is going to make it even harder to get the powder into those internal corners. If this is the case, adjust your flow and increase the amount of powder leaving the gun.

About adjusting some crucial parameters:

- The velocity of the air flow should be sufficient to transfer the powder inside the recess. But it should not be very big, otherwise it will interfere with the settling of powder particles.

- It is necessary to control the electrostatic field so that powder is hardly influenced by Faraday cage.

- Voltage should be reduced, and try to reduce or increase the distance from the sprayer to the product.

Some important tasks before powder coating：

- Check the confition of powder, if your reclaimed powder is too fine, it will not carry a charge as well, meaning the risk of a Faraday Cage is increased.

- Heating the parts before powder coating can help the powder spray more evenly into those tough areas. This step increases the overall film build and how well powder grips to the internal corners.