Powder coating

Corrosion and erosion resistant paint layer for maximum protection and a flawless appearance.

Advantages powder coating

  • High quality coating
  • Available in every imaginable RAL colour
  • Excellent mechanical resistance
  • No use of solvents for a better environment!
  • Lower costs than conventional coating
  • Many possibilities with special coatings and effects that cannot be achieved with other techniques
  • Applicable for products that require a thick coating for maximum protection
I would like to know more about the possibilities of
powder coating at Kalfsvel!

No own transport possibilities? We are happy to help you out!

Please contact us via the contact page to discuss the options.

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15 to 20 minutes in the oven
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from 130 to 200 °C

Applications

Powder coating is used for many different types of metals such as steel, Iron, Aluminium, Copper, Zinc, etc. Products, such as car rims, sheet metals, crane parts, drill heads, car parts, aluminium frames, bicycles, street and office furniture can also be powder coated.

“Kalfsvel Coating has been the specialist in powder coating for an extensive period. Thanks to our many years of experience, we guarantee maximum quality in every situation. ” – C.O. Kalfsvel

Powder coating process

During powder coating, a negatively charged paint powder is sprayed under pressure (compressed air) onto an electrostatically grounded product. This in effect makes sure that the paint powder sticks to the product, after which the whole goes into the oven. At a temperature between 130 – 200 ° C, the powder behaves like a conventional paint, flows and forms a perfect layer around the treatment surface of the product.

Most powder coatings are 2-9 component coatings, the components only give the desired end result after 15 to 20 minutes at 150-200 ° C. This process is also called stoving. After cooling, the product is ready to use or ready for further processing. The maximum hardness of the coating or mechanical load is immediately achieved.

Before this process can take place, the product must first be properly pre-treated.

Pre-treatment

First the product is cleaned. This removes residues from, such as, sand, oil or fats, rust and welding slag. This is essential for the success of the rest of the powder coating process. Various mechanical and / or chemical methods are used for this.
Blasting is used for the mechanical removal of contamination from the surface. Kalfsvel Coating shines to a fine grain of corundum (aluminium oxide). The correct anchor pattern is now created for a good adhesion of the coating.

By applying the correct grain size and pressure to each material, the aesthetic part can also be guaranteed after powder coating. If a too coarse grain is used for blasting, the impact is so large that you can see it in the coating. If the grain is too small, the coating does not have the maximum adhesion to the surface (service life). The impact is greater if you increase the pressure during blasting and our Corundum breaks at a pressure higher than 6 bar. This in effect results in a higher roughness impact, with the result that the coating shows those contours. The selected grain size and work pressure are in direct relationship with each other, which is why this balance must be strictly maintained.

Phosphates or chromates are used in the chemical removal of surface contamination. The product is (often in several steps) bathed or the agent is sprayed onto the product. This chemical cleaning ensures that the powder adheres much better to the material. This treatment takes place in continuous ovens at other companies, but it is environmentally harmful.

Spraying process

The powder is sprayed onto the metal product with an electrostatic spray gun. It receives a negative electrical charge from the spray gun. The powder is sprayed on the product. Because the product is grounded, the powder is drawn to the workpiece by the electrostatic charge.
Another method is the so-called “tribo-charging”, where the powder is charged by passing it along the wall of a Teflon tube. The powder is positively charged by this frictional tension. These charged powder particles then attach to the grounded substrate. This method is not applied by Kalfsvel Coating.

Curing

Most thermosetting powders are cured at a temperature of 180 ° C for 10-15 minutes. A chemical reaction then develops, resulting in a polymer with a higher molecular weight density. This process is called crosslinking.

Possibilities of coating thickness

In order to gain optimal results in the operation, the particles of most powder coatings have a size that is between 30 and 50 microns (μm) and it has a glass temperature of 200 ° C (the temperature at which a plastic is softened). Powder coatings with this particle size must be thicker than 50 μm to get a smooth layer. Kalfsvel Coating usually works with a minimum of 60 – 80 μm and for outside uses, a thickness of 80 – 100 μm per layer is used.

The layer thickness is determined based on the end product. A rougher thick coating is preferred by many, which means that any defects in the metal can be easily concealed. A rougher coating is also less sensitive to fingerprints.

In specialized processes, powder coatings of less than 30 μm can be applied, possibly with a glass temperature lower than 40 ° C. This makes thinner coatings possible.

If it needs to be thinner, a variation of dry powder coating can be applied, the “powder slurry process”, combining the advantages of powder coatings and liquid coatings by distributing very fine powders of 1-5 μm particle size in water.

Powder coating variants

Powder coatings are divided into two main categories, the thermoplastics and thermosets. A thermoplastic powder melts and flows to form the final coating. No reaction takes place during baking.

A thermoset powder contains a commonly named cross-linking agent. All molecules are being chained to a network where a cross-linked coating is formed. During baking, the various components of the powder react with each other to form a polymer.

Commonly used polymers are polyester epoxy (also known as hybrid), polyurethane, polyester, fusion bonded epoxy (direct epoxy) and acrylic.

Contact us without obligation. We are happy to talk to you personally. Mail info@kalfsvel.nl or call 0031 (0) 75 6174355.

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