How does the powder coating work

How does powder coating work and what is it good for?

Basic knowledge of powder coating: protection and optics in one

Powder coating is a surface treatment process in which the applied layers not only offer protection against corrosion, but also meet optical requirements. Because the powder coating can be applied in an almost inexhaustible variety of colors: In all RAL tones from white to black, special colors as well as NCS and RDS color systems are possible. This is why the process is also used in a wide variety of industries, from the construction industry to automotive to mechanical and plant engineering.

How the powder coating works

In powder coating, powder is electrostatically charged and sprayed onto the component to be coated. Before the actual powder coating, the workpieces must be cleaned and pretreated, whereby phosphating, KTL coatings and galvanizing can be used for priming; the pretreatments can be combined with each other depending on the corrosion requirements.

The components are then transported to an application system. There the powder is applied to the workpieces and then burned in at approx. 180 ° C. Here, the powder coating is interlinked, is permanently anchored to the workpiece and is later given a decorative appearance. A conveyor system transports the components to the various stations in the coating process.

The powder consists of the finest solid particles based on polyester and epoxy resins. Powder coating is a very sustainable, environmentally friendly and almost waste-free coating process, as it contains neither solvents nor heavy metals and excess powder is recovered. As part of the recovery process, powder coating that has not been applied to the workpieces is collected, processed and fed back into the coating process.

Advantages of powder coating

The powder used and the pretreatment decisively determine the properties of the coating. The applied powder layers are usually relatively thick, between 60 and 180 µm, and ensure high corrosion resistance. Compared to alternative coating processes such as wet painting, the process also offers higher impact and abrasion resistance. In addition, powder-coated components are more resistant to chemicals and weathering.

The powder coating system of the Holzapfel Group is suitable for workpieces up to a length of 2,000mm, a width of max. 650mm and a height of 1,400mm and a maximum weight of 30kg.

For maximum protection against corrosion, the components can be coated with zinc-nickel in advance. Then they are provided with a zinc phosphate coating, coated with KTL and finally provided with a powder coating. The Holzapfel Group also takes on downstream processes such as assembly activities.

    Example of powder coated industrial springs @Pixel_B - stock.adobe.com

Advantages at a glance

  1. High chemical and UV resistance
  2. Stone chip resistance
  3. Good coverage of small irregularities in the substrate of the component thanks to the high layer thickness of the powder coating
  4. Decorative, even surface
  5. High corrosion protection
  6. Very temperature and weather resistant
  7. Shock, impact, scratch and abrasion resistant surface
  8. Excellent edge coverage
  9. Individual coloring possible through the entire RAL color spectrum as well as special colors and NCS, RDS color systems
  10. The powder surface can withstand extreme mechanical loads and is elastic at the same time
  11. Powder coating can also be bent or deformed to a certain extent
  12. In the duplex process with a base layer of zinc, zinc alloys or KTL, a powder coating is also possible for particularly high corrosion protection (> 1000 h) against base metal corrosion (salt spray test according to DIN EN ISO 9227).
  13. Electrostatic process is "self-limiting", i.e. excess
  14. Powder is repelled (back spray effect)
  15. Environmentally friendly by recovering the excess powder
  16. Powder coating without toxic, flammable and explosive solvents and without heavy metals
  17. Normally no primer required for indoor use

Almost all metals can be refined with a powder coating, but mainly steel and aluminum are powder-coated, as well as zinc die-cast, iron materials, cast and pre-galvanized substrates. In general, it is essential that all parts of a workpiece that is to be provided with a powder coating must be heat-resistant in order to withstand the stoving process.

Would you like an example? Read now how the Holzapfel Group coats components for a construction machinery manufacturer with powder and which services round off the overall package!

Special feature: ultra-thin powder coating

Incidentally, the Holzapfel Group can too Ultra thin layer powder Apply with particularly thin layers - Find out more about the Ultra thin powder coating!

More about powder coating and a contact for inquiries can be found at https://holzapfel-group.com/oberflaechenverfahren/pulverbeschichtung.html