Powder Coatings Electrostatic vs Fluid Bed

For most coating requirements powder is sprayed and charged electrostatically through spray guns onto the work piece. Other methods include fluidised bed dipping, powder cloud and electrostatic brush application. Most of the methods used fall into one of the following processes:

1. Electrostatic spray process

- Corona spray gun
- Tribo spray gun (see Corona vs Tribo page)

2. Fluidised bed process

The advantages and disadvantages of the electrostatic spraying process and fluidized bed process are compared below. It is clear that both methods have their typical fields of application. In most cases, the electrostatic spray process is more flexible and versatile.

Electrostatic Powder Spraying:

Advantages

1) Difficult shapes can be coated

2) Film thickness between 30-250

3) Simple and low cost for automation

4) Colour can be changed relatively simply

5) No pre-heating of components required

Disadvantage

1) Cost of equipment is higher than a fluidised bed

Fluidised Bed Process:

Advantages

1) Very high film thickness (>250m ) can be applied in one application and curing cycle

2) Low initial plant cost and maintenance

Disadvantages

1) Relatively large volumes of powder are required to charge the plant

2) The work-piece must be pre-heated and in some cases post cured in order to obtain the required result

3) This application can only be used where relatively thick films are required

4) The components should be of simple shape to avoid powder entrapment

5) Thin gauge material cannot be coated by this method due to its low heat capacity

6) A film thickness of between 200-250 microns is average

7) Colour change must be achieved by additional beds