SPW Engineering

SPW Engineering

437 Joseph Street,
Ballarat. 3350
Victoria, Australia.

PH:   (03) 5331 5400
FAX: (03) 5331 5911

Where to find Us

Powdercoating

Powdercoating

SPW Engineering - Powdercoating

Powder Coating is sometimes referred to as dry painting. It uses an electrically charged polyester powder paint which is sprayed on to an earthed work-piece, such as a wheel, using a special low ampere spray gun. The electrostatic charge holds the powder on the work-piece as a fine coating until it is transferred to the oven.

In the oven the work-piece is heated to a temperature of around 200°C which causes the powder to melt and fuses it to the work-piece. The melting process causes the paint to flow resulting in a superb finish which is scratch resistant and up to three times stronger than solvent based paints.

Solvent based paints take several weeks to reach full hardness and are much less environmentally friendly than powder coating. Polyester coatings are suitable for both indoor and outdoor conditions are are available in a range of gloss levels and textures.

Coatings are available in all Standard Colours and in addition, many other special colours and finishes are also available, please ask for details.

All metal items can be considered for powder coating so just give us a call and we will be happy to discuss your requirements.

Advantages and disadvantages of powder coating

There are several advantages of powder coating over conventional liquid coatings:

  • Powder coatings emit zero or near zero volatile organic compounds (VOC).
  • Powder coatings can produce much thicker coatings than conventional liquid coatings without running or sagging.
  • Powder coating overspray can be recycled and thus it is possible to achieve nearly 100% use of the coating.
  • Powder coating production lines produce less hazardous waste than conventional liquid coatings.
  • Capital equipment and operating costs for a powder line are generally less than for conventional liquid lines.
  • Powder coated items generally have fewer appearance differences between horizontally coated surfaces and vertically coated surfaces than liquid coated items.
  • A wide range of specialty effects is easily accomplished which would be impossible to achieve with other coating processes.

 

While powder coatings have many advantages over other coating processes, there are limitations to the technology. While it is relatively easy to apply thick coatings which have smooth, texture-free surfaces, it is not as easy to apply smooth thin films. As the film thickness is reduced, the film becomes more and more orange peeled in texture due to the particle size and TG (glass transition temperature) of the powder.

For optimum material handling and ease of application, most powder coatings have a particle size in the range of 30 to 50 μm and a TG > 40°C. For such powder coatings, film build-ups of greater than 50 μm may be required to obtain an acceptably smooth film. The surface texture which is considered desirable or acceptable depends on the end product. Many manufacturers actually prefer to have a certain degree of orange peel since it helps to hide metal defects that have occurred during manufacture, and the resulting coating is less prone to show fingerprints.

Powder coatings have a major advantage in that the overspray can be recycled. However, if multiple colors are being sprayed in a single spray booth, this may limit the ability to recycle the overspray.