Surface finishes in the manufacturing industry have evolved rapidly over the last two decades. Coatings play a critical role in the decoration and protection of your products. This has fueled the rise in popularity for powder coats over liquid coating in industrial finishes. As of 2019, the global market share for industrial powder coating stood at $12.39 billion. In the US, 10% of total industrial finishing applications use this technology. Here is an in-depth analysis of what makes professional powder coating popular.
It is a finishing process that involves the use of dry powder that is applied electrostatically to the surface of the substrate. The product then passes through a curating oven where the powder coat melts and blends over the surface to form a hardened coating. The result is a glossy finish that is resistant to corrosion, abrasion, and fading.
Before the application of the dry powder, the material must be cleaned and treated. Sandblasting removes dust, dirt, and debris that may affect the quality of the final finish. The manufacturer gets rid of rust, oil and grease residues by dipping the substrate in weak alkali and neutral detergents. It results in a clean and smooth surface ready for professional powder coating. The wash stations have sections for cleaning, rinsing, etching, blasting, and drying.
There are two techniques used, depending on the nature of the powder coating material. These are:
- Thermosets: The powder material has resin additives made from polyester, polyurethane, epoxy, and acrylic. The blended powder melts and undergoes irreversible chemical cross-linking reactions. The reactions produce long-chained polymer molecules that harden to a thick, even, and glossy finish.
- Thermoplastics: There is no addition of resins, with the powder melting and fusing with the metal material to form a tough coat.
The two main methods are:
- Electrostatic deposition: This is the most common technique for metal substrates. The application uses an electrostatic spray gun to deposit charged dry powder on the surface of the metal. The spray booth acts as a work area, as well as a filter for powder overspray.
- Fluidized bed powder coating: The material is dipped into a fluidized powder bed where the powder particles cover the surface of the substrate. An electrostatic fluidized bed generates a cloud of charged powder particles above the fluid where the products are passed through.
Products coated with electrostatic deposition must be cured in a powder curing oven. The temperature and time for the cure depend on the material’s size, shape, and thickness. Most ovens operate between 350°F to 450°F. The powder melts and flows over the surface, forming a continuous film.
Products passed through fluidized beds are heated before powder application. As the heated material immerses into the powder, the particles melt and flow in contact with the heated surface, forming a thick coating.
Once cooled, the product can then be assembled packed and shipped for the market. Powders coatings are free of solvents and have negligible amounts of volatile organic compounds (VOC) present in wet paints. This makes powder coats to be environmentally friendly, increasing their demand.
Professional powder coating is a multi-step process that guarantees durable finishes for your products. The coat is also corrosion resistant and environmentally-friendly. For additional information on the powder coating process, talk to the team at Professional Finishing.