powder coating aluminum profiles

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Powder coating aluminum profile
Powder coating electrostatically charges the powder and sprays it on to the aluminium extrusion, and then fuses it into a smooth painted coating in a curing oven. powder is a mixture of finely milled resin and pigment, it gives a good resistance to UV and corrosion but with various choices of colors. The chrome-based chemical pre-treatment increased better adhesion between profile surface and powders, coating thickness is normally 60 – 120 μm.

Powder coating is a form of protective coating which is applied by electrostatically charging and spraying dry powder. The powder coating is preferred to liquid coating because the powder does not need to be placed in a liquid solvent and it does not emit volatile organic compounds into the atmosphere. This makes it more efficient and less hazardous.

The powder coating process is usually divided into three parts - preparation, spraying and curing. First, the aluminum profiles are prepared by cleaning, rinsing, etching, rinsing, chemical treatment,  rinsing and rinsing again with de-ionized water. During the preparation process, oil and grease are removed with neutral detergent and the surface is etched to take off heavy oxides. After rinsing the aluminum, it is dipped into a phosphate or chromate solution to produce a conversion coating on the surface of the metal. The conversion coating gives the profiles a more adhesive surface than the natural oxides that form on the aluminum surface. It also minimizes the occurence of film corrosion. After rinsing the aluminum profiles in de-ionized water, to reduce chemical salts attached to the metal surface, profiles are moved to the spraying section.

The powder coating is normally applied with a set of automated electrostatic spray guns. The gun gives the powder a positive charge and sprays it towards the profile with the aid of compressed air. The profiles, which are at ground potential are arranged for spraying either horizontally or vertically.

Before the powder gets to the gun, its individual grains are separated through a process known as fluidization. This ensures that the powder flows to the gun without any hindrance. The powder will get attached to the profile while the electrostatic charge remains. But to ensure that it has a solid, abrasion resistant and permanent effect on the aluminum surface, the thermoset powder on the coated profiles must be cured in an oven.

At a very high temperature, the thermoset powder will melt and flow out. It reacts chemically to create a polymer network with a higher molecular structure. The curing process, also known as cross-linking, occurs in a curing oven, at a temperature of about 200 degrees Centigrade, for less than a quarter of an hour. When the powder is fully cured it will have a smooth and attractive look and form a hard abrasion-resistant surface.

Powder coating is available in a wide variety of colors. The process allows clients to choose their color with the appropriate RAL, RGB or pantone value or use a sample of a cut off metal to get an accurate match. The powder coating is done with our advanced conveyor system and we can provide profiles that are as long as 6 meters.

To ensure that the powder coating remains well bonded and resistant to wear and abrasion, we use very strict quality control and quality assurance standards. We also use a protective film to protect the powder coating where necessary. This helps to reduce any damage due to abrasion while the profiles are in transit.