Powder Manufacture & Application

How is powder made?

It’s actually a pretty simple process. The raw materials are weighed out and mixed together - that's called premix. The premix is then put into an extruder, which uses controlled heat and pressure to completely homogenize the mix. The hot extrudite is then forced out through chilled rollers, which cool it very quickly, making cold, thin and brittle sheets of hard material. These long sheets cool on the cooling rack and then are broken up into small chips and then ground down into a powder.

Making metallic or 'sparkly' powders

Sparkle effect or metallics have an extra step. The powder is made in the same way, but we then bond the powder and mica. The bonding process makes the tiny metallic flakes stick to the powder particles. It ensures a more even and professional finish. At IFS we do most of our bonding in house, for a professional, quick, efficient and cost competitive bonding process.

Making adjustments to color

Because everything is heated up and mixed together during the extrusion process, then cooled and ground down, if the color is not quite right, we have to start again. Once the raw materials have been through the extruder, they are all melted together - we can’t “unmelt” them. So, if the color isn’t quite right, then we start all other again, adjust the pigment quantities, and create a whole new powder.

Powder Application

At IFS we manufacture powder, we don’t actually apply it. There are thousands of powder coaters all over the USA who do a great job of applying powder to the substrate. However, while there are a few different ways of applying powder, the most common is electrostatic application.

In this method, the powder is placed in a hopper and fluidized, which essentially means air is pushed through the powder which makes it behave like a liquid. The fluidized powder can then be pumped from the hopper, through hoses to a powder spray gun.

The parts to be coated are hung on a moving conveyor and they are grounded.

At the end of the spray gun there are some electrodes. When you fire the powder gun, the powder is discharged and picks up the electrostatic charge from the electrodes at the end of the gun. The electrostatically charged powder is therefore attracted towards the grounded parts. The electrostatic bond keeps the powder on the part. Once the part is covered in powder, the conveyor then carries the parts to an oven.

Each powder comes with its own cure schedule, which tells us how hot the oven should be and how long the powder coated part should stay in the oven. Once the coated parts are in the oven for the required amount of time, the powder heats up then melts, flows and gels. As it gels and cools a whole new chemistry is created on the part. That is what makes powder so tough, hard and scratch resistant.

Tribostatic application

In tribostatic application, the powder particles are charged by rubbing along a specially designed tube on the inside of the powder gun. The particles become charged using friction and are then attracted to the grounded parts. Using a tribo gun often requires a different formulation of powder than a corona gun.

Fluidized bed application

Another way of applying powder is to use a fluid bed. In this method a fluidized powder bed is created and the parts are “dipped” into it.

Pre-treatment

Pre-treating the substrate before applying powder to it is important. At the very least the parts to be coated should be cleaned and have any dirt or oil etc. removed from them. If this is not done then you are going to get powder coated dirt, oil and grease and this will not only affect how the powder performs but also how the substrate performs beneath the powder.

For certain applications such as architectural applications, a complete pre-treatment program is recommended. Good pre-treatment is essential for adhesion and corrosion protection. 

During this type of pre-treatment process the parts are cleaned using water of a specific PH level, then the chemical pre-treatment is applied. With powder coatings a chrome-based pre-treatment or a non-chrome pre-treatment can be used. Once the pre-treatment chemicals have been applied, the parts are rinsed and then sent through a dry-off oven which quickly dries the parts, so they are ready to be powder coated.

With powder coatings, there is no primer-chrome based or otherwise - required after the pre-treatment of aluminum. This is a huge advantage over liquid coatings as it is one less layer of paint, process, energy and time.

When coating steel, a powder primer is recommended. If corrosion is a concern, then a zinc rich powder primer may be used, otherwise a standard epoxy-based primer helps deliver another layer of protection and performance.