Coating of metal

Date:

04.07.2008 - 03:26

Coating Processes

A number of processes are used in a variety of coating applications

• fluidized bed coating is used especially for wire products,
• electrostatic coating for corrosion protection and decorative metal coating, and
• the minicoating process for industrial small components.
• The flame spray process is particular favored for repair work.

Fluidized Bed Coating Process

Since 1952, fluidized bed coating technology has been used for powder coating. It is the most cost-effective method for plastic-coating preheated, primarily metallic objects. The technology combines fluidized bed and dipping processes. Layer thicknesses of 250-500 microns are achieved, with a minimum of tooling; even coatings of 1-2 millimeters are possible.

Steel, metal-alloy, and aluminum workpieces are coatable, regardless of their geometry. For this purpose, the pieces are dipped in fluidized VESTOSINT® powder for a few seconds. The powder sinters to the surface of the piece and fuses into a smooth surface, thanks to its residual heat.

Important applications for the fluidized bed coating process with VESTOSINT® are

• wire products of all kinds (e.g., dishwashing racks and deep-freeze racks)
• industrial components such as springs, rolls, drive shafts, valve handles, stay bars and much more.

Electrostatic Coating Process

In the electrostatic coating process, VESTOSINT® powder is electrostatically charged as it exits a powder gun and sticks to the grounded metallic portions to be coated. These portions are subsequently heated to a temperature above the melting point of the powder (ca. 176°C), causing the powder to fuse into a smooth, nonporous plastic film.

The process works without solvents and produces no harmful substances. Electrostatic powder coating thus provides an ecological surface finish.

Electrostatic coating is used in almost all areas of corrosion protection and decorative metal coating.

Minicoating Process

The principle of minicoating is similar to that of fluidized bed coating. Hot (small) parts drop into a fluidized VESTOSINT® powder pan. As they fall, the powder sinters to the metallic surface. The objects are subsequently conveyed out of the VESTOSINT® container in a vibrating trough and the surface is further smoothed, no matter what the shape of the articles being coated.

The main fields of application of minicoating include the coating of brassiere parts and component coating for the electrical and automotive industries.

Flame Spray Process

In addition to classical application processes, VESTOSINT® powder may also be processed in the flame spray process. In this process, the powder is fed into a flame-spray gun where it is surrounded and melted by a circular flame. It is then applied to the surface to be coated. Since the process can be used anywhere, it is particularly favored for repair work and for coating pipe bushings, tanks, and similar objects.