PAINTING – GALVANIZING – SILKSCREENING
2 variants are viable for the painting of iron, aluminum and steel parts, namely:
Painting with liquid products offers a wide range of practicable solutions, thanks to the numberless cycles that can be performed and by the chemical and physical properties of the paint.
Painting provides a special finishing to the object that has to be treated, thus making the surface smooth and glossy, protected by a film layer that ensures anti-corrosive properties and protection against the chemical agents.
The advantages of liquid painting certainly include a simpler processing cycle, which is – subsequently – faster and cheaper, as well as a limitless range of shades of colors. Its disadvantages are – though – lower resistance to the atmospheric agents and the severer issues to both the operators and the environment because of the use of solvents.
Powder painting mainly uses epoxy powders or polyesters.
The thermosetting powders based on polyester resins form hard stretched films with optimum chemical characteristics on the surface of the part, thus giving it anti-corrosion properties and – subsequently – ensuring the finished product a longer life span.
Powder painting represents an optimum solution for several industrial parts.
The process is called polymerization: the pigmented powder is sprayed on the parts and it remains electrostatically attached to it. The powder is then melted in the polymerization oven, at a temperature which varies between 180°C and 220° C, for the time required.
The powders applied can be of different nature: epoxy, epoxy-polyester and polyester, with options of obtaining smooth, textured or embossed finish in all the wished color shades.
At the end of the polymerization, the part is ready to be removed from the chain once cooled down,
The thickness of layer painted by this technology is remarkably greater than the one that can be obtained through liquid painting and – subsequently – the part is more resistant to both the chemical and atmospheric agents.
No solvents are used, and this remarkably reduces the risks for both the environment and the operators.
There are different methods of galvanizing, namely:
- Hot galvanizing: The part is immersed into molten zinc and – thanks to this “hot bath” – is coated by a robust layer of zinc that ensures efficient resistance against corrosion.
- Electrolytic or electro-galvanizing: The part is immersed into a salt solution containing zinc, and electric current is made pass through it. By this process, the metallic zinc deposits onto the surface of parts, thus inhibiting the generation of rust and protecting against corrosion
- Cold galvanizing: A coating of the metal surface, more similar to painting. Polymer-linked zinc powder paint is used and applied like a standard primer, on which a second – finishing – layer shall be applied.
- Zinc spraying. By this process, finely pulverized molten zinc is sprayed – through special guns – on a metal surface which was previously sand-blasted.