Decoding Coil Coating Process

What is Coil Coating Process

Coil Coating Process is a method of applying organic coating material on rolled metal strip substrates in a continuous process. This process includes: decoiling and cleaning, chemical pre-treatment of the metal surface (single or double-sided), single or multiple applications of (liquid) paint or coating powder, subsequent curing or laminating with plastic film, cooling, and recoiling the same roll, so it can be delivered to a sheet machine, slitter, or manufacturing plant.The Basic Principle of Coil Coating Process is that materials pass continuously through various process stages. Thus, the coated material has very consistent performance. In addition to obvious labor efficiency, environmental benefits, and energy savings; coiled coating materials are inherently more consistent than products produced on a part-by-part basis.

Types of Coil Coating Process

Reverse Roll Coating Process

In this process, the paint circulates in a paint pan, with a rotating pick-up roll partially submerged in the coating, moving counterclockwise, which then transfers the coating to a clockwise-rotating applicator roll. This specific configuration is used for most products and can achieve a coating thickness of 25 microns in most coatings.

Direct Roll Coating Process

Thinner coatings and printing use a similar setup, but the rolls work in the opposite direction, so the applicator roll surface moves in the same direction as the coil, while the pick-up roll moves in the same direction as the applicator roll. Direct coating requires additional equipment due to the hazardous pinch point between the two rolls.

Three-Roll Coating Process

If the coating machine is equipped with an additional roll, a third configuration can be used. Three-roll coating is typically employed for those coatings requiring extra thickness, such as PVC coatings and coatings applied as stripes with bare edges. This is quite common when producing materials for garage doors and lighting fixtures. Three-roll coating uses a third roll located behind the pick-up roll, with all three rolls rotating clockwise.

Main Applications and Key Benefits of Coil Coating Process

Virtually, all appliance category products are produced using coiled materials coated with polyester. For the long-term prosperity of the coil coating industry, it will continue to provide advantages superior to competing industries in several fields:

Product Durability

Some building products have a lifespan of up to 40 years without repainting. Suppliers typically provide warranties to reinforce their claims.

Recyclability

Pre-coated metals are fully recyclable, and there is a feasible infrastructure to recycle scrap metal.

Low Consumption of Consumables

The coil coating process embodies inherent efficiencies such as high coating transfer efficiency and custom width substrates.

Low Emissions

Low waste emissions, including water and VOCs.

Quality Consistency

Coil coating is a highly automated continuous process that helps in producing consistently high-quality products.

Cost-Effectiveness

For most applications, the coil coating process represents the most cost-effective way to paint metal surfaces.