Wet Painting and Powder Coating

Painted sheet metal fabrication supplier

Electropak has two paint plant facilities – a conveyor coating plant for powder coating, and a batch processing plant for powder coating and wet spraying.

How Does Powder Coating Work?

Powder coating is commonly used in the manufacture of metal products and fabrications.

Powder coating is based on the principle that objects with opposite electric charges (positive and negative) attract one another.  Powder particles are negatively charged by passing them through a special spraying gun.  This results in an electric field between the spray gun and the earthed component.  The powder particles then follow the field lines and adhere to the product.

The component is then conveyed to an oven where the powder is baked at temperature of 160 to 200 degrees C for approximately 20 minutes.  Most conducting or thermally stable materials are suitable for powder coating and metals are particularly good due to their high electrical and thermal conductivity.  Complex metal components can be powder coated evenly with excellent adhesion.

All products are cleaned and treated prior to powder coating to ensure correct adhesion.  Electropak uses a typical three-stage pre-treatment spray system on its conveyor line.

Stage 1:  Clean and Phosphate (temperature 50 degrees C), 90 seconds
Stage 2:  Rinse, 45 seconds
Stage 3:  Clean water rinse, 30 seconds.

Components are then dried at a temperature of between 100 and 120 degrees C before the powder is applied.

Powder Coating Frequently Asked Questions

What is the maximum size of components that can be coated using Electropak’s powder coating plant? The maximum dimensions of a part are 3 metres long, 600mm wide and 1.5 metres high.

Can components be re-coated using a different colour, if they are already coated, and will the old colour show through? Yes, parts can be re-coated using another colour, but certain colours (like red or purple) can cause problems.

Do you carry out subcontract powder coating on free issue components? Yes, we powder coat various different components for some of our customers.  Some send their own powder to help with the cost of the painting.

Will you be able to provide me with the COSHH data sheets for the product being used?
We have copies of COSHH data sheets for all our stock powders.  If we are coating using a non-standard powder, if required, we can obtain the data sheet direct from the supplier.

Can powder coated components be used outdoors? Providing the correct type of powder is specified then parts can be used outside.

Have you got a colour chart, or a list of paints that you have in stock?
There are various different colour charts available and we keep a stock record of all the powders we use.

Does powder coating chip off laser cut edges? Components that are laser cut with oxygen (typically those made from mild steel) have a layer of metal oxide on the profiled edges.  This layer can be removed by dressing or by an aggressive pre-treatment solution, or avoided altogether by using nitrogen cutting.  If the oxide layer is not removed prior to powder coating, it has a tendency to chip off, taking the paint with it.

Is powder coating as good as wet painting? Wet painting is more resistant in outside conditions because of the primers used, but it is much more expensive and time consuming.  Powder coating is more cost effective, and in many cases, can still be used outside.

Can parts have a primer applied before the main coat? Yes.  Primers are available in both powder form (such as “Zinc Primer”) and wet (which can be baked dry prior to final coating).  Primers are only recommended if the components need to endure extreme conditions due to the increased cost.

Electropak – the precision sheet metal fabrication company.