Processe - Powder Coating

POWDER COATING

The powder coating heating process is a critical step in the application of powder
coatings to various surfaces, such as metal, plastic, or even wood. Powder coating is a
dry finishing process where a fine powder of pigment and resin is applied
electrostatically to a surface. The coated object is then heated to enable the powder to
melt, flow, and cure into a durable, protective, and visually appealing finish. The heating process, often referred to as curing, involves specific temperatures and durations to achieve optimal coating performance. Here's an overview of the industrial processes:

Application Method of Powder Coating

Electrostatic Application Method: The powder coating (thermoplastic or thermoset polymer) is applied to the substrate using an electrostatic spray gun. The positively charged powder particles are attracted to the grounded or negatively charged object, until melted or fused ensuring an even coating.

Curing in the Oven

Purpose: The primary purpose of the curing process is to melt and fuse the powder particles into a continuous film, creating a durable and protective coating.

Temperature Range: Curing temperatures typically range from 150°C to 220°C (302°F to 428°F), but the exact temperature depends on the powder coating formulation and the material being coated.

Duration: Curing times can vary but are typically in the range of 10 to 30 minutes.

Cooling

After the curing process, the coated object is allowed to cool to room temperature. The cooling phase is crucial to ensure that the powder coating hardens and adheres properly to the substrate.

Key considerations in the powder coating heating process

Gelation: The powder coating goes through a gelation phase (semi-liquid) during heating, where it transforms from a powder into a gel-like state before eventually curing into a solid film.

Flow and Cure: The coating must reach a sufficient temperature to allow the powder to flow and cover the substrate uniformly. The curing phase involves the chemical cross-linking of the resin, resulting in a hardened and durable finish.

Different Substrates: The heating process can be adjusted based on the type of substrate. For example, metal substrates may require different curing conditions than heat-sensitive materials like certain plastics.

Powder coating offers advantageous solutions such as durability, corrosion resistance, and a wide range of color options. The precise temperatures and durations in the heating process are crucial factors in achieving a high-quality, long-lasting powder coating finish.

INDUSTRIAL POWDER COATING OVENS

Industrial powder coating is typically done through a two-step process: first, the coating
is applied to the part electrostatically, and then the newly powdered part is cured under
the heat of our industrial powder coating ovens to form a hard-plastic coating. This process is efficient since the powder wraps around the entire part for better coverage and can provide 95% material usage of the powder. There are two different types of
powder used for coating parts – Thermoset and Thermoplastic.

Thermoset Powder
Thermoset powder is used most often for powder coating since it results in a nice surface layer, creating a finished look and providing durability. It also reacts when baked with other chemical groups in the powder to polymerize harder, which improves the performance properties. After curing thermoset powder in our powder coating ovens, itcannot be melted back into a liquid from further heating.

Thermoplastic Powder
Unlike thermoset, the thermoplastic powder does not permanently change during baking and will be remelt if heated. These types of coatings can be found on refrigerator shelves or metal benches, for example. Thermoplastic powder coatings provide a functional, flexible, and durable coating for a variety of materials.

Wisconsin Oven manufactures industrial powder coating ovens that are designed to
prevent powder blow-off and provide uniform air distribution along the entire length of the work chamber which reduces rework, saving you time and money. This also results in quality cured finishes and optimum cycles. These industrial ovens are factory adjusted and tested prior to shipment from our facility to help reduce installation and start-up times.

Our powder-coating oven configurations include reach-in, walk-in, and top-load designs
and are available in hundreds of sizes.

Products associated with the process

Pyradia has developed the most advanced line of Drop Bottom Ovens for aluminum solution heat treating. These ovens incorporate state of the art insulation, control system, and hoist mechanism, which make them the most performing and reliable on the market.

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