The-Benefits-of-Powder-Coating-Finish-for-Metal-Fabrication

Electrostatic powder coating

Electrostatic field painting is a manufacturing process that uses charged particles to paint a particulate piece more efficiently. The paint in the form of powder or atomized liquid is initially designed to a conductive workpiece using normal spray methods, and is then accelerated to the workpiece with a strong electrostatic charge.

An addition to the electrostatic coating process is the sinking of the conductive piece into a paint tank which is then electrostatically charged. The ionic bonding of the paint with the metal creates the paint layer, in which its thickness is directly proportional to the length of time the parts are left in the tank.

After the pieces are extracted from the paint tank, they are rinsed to remove any residual paint that is not ionically bonded, leaving a thin film of electrostatically bonded paint on the surface of the piece.

Surface treatment

To ensure good adhesion to the surface, it is recommended to check it before application to ensure it does not show any traces of: lubricants, oil, wax, rust or other contaminants. Otherwise, the paint will not provide adequate surface protection, resulting in premature corrosion and low adhesion. A thorough cleaning of the application area is recommended. For increased corrosion resistance, chemical surface treatment is recommended, eg chromating or equivalent for aluminum and phosphating for steel.

Surface preparation

Steel surfaces

Oils and greases can be removed by solvents or washing emulsified agents, then by water or vapors washing and taking care not to be spread in the uncontaminated areas;
Washing solvent: white-spirits;
It is not recommended degreasing only by manual washing with solvents because it leads to spreading of a fine grease film on the surface which can affect the coating;
After a coarse removal by solvents, it is recommended washing by detergents or emulsified agents, followed by a perfect rinsing with drinking water and a drying process;
The edges and corners shall be specially considered;
The degreased surfaces shall not be touched by hands because perspiration contains salts;
All the welds and sharp edges shall be rounded and the welding slag shall be removed;

The surface preparation shall be continued according to the following versions:

Version 1

The sufaces shall be blasted until the grade ISO-Sa3 as per ISO 8501-1: 2002;
Dust shall be removed by aspiration, brushing or cleaning by a cotton cloth;
They shall be phosphate coated by their immersion into a water solution of iron/zinc phosphate in order to get a layer with a thickness of 1-10μm;
Salts shall be removed by washing with water followed by a drying procedure.

Version 2

The sufaces shall be blasted until the grade ISO Sa 2½ -Sa 3 as per ISO 8501-1:2002;
Dust shall be removed by aspiration, brushing or cleaning by a cotton cloth;
The blasted product shall be preserved until paint application in a dry area where the surface cannot be moistened or contaminated by oils, greases, dust. In case of contamination, the surface must be blasted again because a simple cleaning by solvent is not enough;
Paint shall be applied in 4 hours for the sand blasting procedure, at most.

Aluminium surface

Oils and greases can be removed by solvents or washing emulsified agents, then by water or vapors washing and taking care not to be spread in the uncontaminated areas;
Washing solvents: white-spirits, perchlorethylene , toluen;
It is not recommended degreasing only by manual washing with solvents because it leads to spreading of a fine grease film on the surface which can affect the coating;
After a coarse removal by solvents, it is recommended washing by detergents or emulsified agents, followed by a perfect rinsing with drinking water and a drying process;
The edges and corners shall be specially considered;
It sahll be chrome coated;
Salts shall be removed by washing with water followed by a drying procedure.

WARNING

To be not applied on the zinc coated surfaces (galvanized), if only the following rules are observed:
Oils and greases can be removed by solvents or washing emulsified agents, then by water or vapors washing and taking care not to be spread in the uncontaminated areas;
Washing solvent: white-spirits;
It is not recommended degreasing only by manual washing with solvents because it leads to spreading of a fine grease film on the surface which can affect the coating;
After a coarse removal by solvents, it is recommended washing by detergents or emulsified agents, followed by a perfect rinsing with drinking water and a drying process;
The edges and corners shall be specially considered;
Zinc oxidizing components shall be removed by brushing and then by water jet washing (120-140 bari) followed by a drying process;
They shall be phosphate coated by their immersion into a water solution of iron/zinc phosphate in order to get a layer with a thickness of 1-10μm or they shall be chrome coated;
Salts shall be removed by washing with water followed by a drying procedure.

NOTE :

Our specialized personnel is available to help clients to get the optimal performances from our products. Recommendations are based on trustworthy tests and information. Nevertheless, as long as we have no control upon the conditions in which the products are stored or used by clients, all the recommendations do not incur our responsibility for any damages coming from the products utilization. Our responsibility shall be limited to the replacement of a potential unproper product. In case of complaints, please keep minimum 250 g of the product in question for contr-expertize.