coil coating on metal sheet after fabrication

Coil coating for cost-efficient, optimized processes

Coil coating is an immensely efficient method of coating metal. It is a continuous and highly automated process which takes a coil of metal through every step of finishing, from cleaning to curing, before being packaged for shipment. The metal arrives entirely finished and ready to be used – the slogan of the industry is “Finish first, fabricate later!”. By opting for coil coating you are choosing a product of consistently high quality that is durable, corrosion resistant, cost-effective, recyclable, and greener than other alternatives. It is also available in a range of coating chemistries and the resulting painted metal sheet can be formed without loss of performance.

In this article we will look at the coil coating process, the different coating technologies used for coil coating, how coil coating benefits fabricators, and coil coating companies in the Emirates.


The benefits that make industry turn to coil coating

Businesses in the building and construction, HVAC, appliance, automotive, transportation, and furniture industries are increasingly using pre-painted or coil coated materials in their manufacturing and building. The reasons for this are manifold:

  • High quality finish: Coating a smooth flat sheet of metal allows the finish to be smooth and consistent while removing the risk of nooks and crannies causing adhesion problems and hiding imperfections. The uniform layer of coating also allows strict maintenance of color consistency.
  • Environmentally friendly: The closed loop of the coil coating system eradicates an enormous percentage of waste associated with the paint process. The coating application efficiency is over 90%, excess metals are recyclable, emissions and disposal are low and well-controlled.
  • Customization: Coil coated metals allow for a wide range of colors, thickness, performance characteristics, and even aesthetics, including printing, stripes, embossing and more.
  • Corrosion resistance: Studies have shown that coil coated metal consistently offers better corrosion resistance than post-painted surfaces. The consistency and accuracy of the painting process also ensures the best possible protection and finish.
  • Reduced costs: Coil coating significantly reduces or eliminates paint wastage, material handling costs, energy consumption, hazardous waste disposal, insurance premiums, capacity restraints, and the cost of compliance.

The continuous coil coating process step by step

The continuous process of coil coating starts with an untreated coil of metal sheet which is unwound, treated, coated, cured, rewound, and packaged for shipment at a rate of 100-200 meters per minute. This process can be for one or both sides of the metal sheet, and can apply and cure up to three layers of paint. The metal sheet is most commonly aluminum, steel or galvanized steel, and coil dimensions vary –  for steel the average coil is 1.6m wide and 0.5mm thick, where aluminum lines are typically larger at 2m wide. The typical line will include decoilers, entry accumulators, brushers, coaters, treatment and quenching tanks, curing ovens, and finally recoilers. The coil coating process looks like this:

  1. Stitching the strip to the previous coil
  2. Cleaning the strip
  3. Power brushing
  4. Pre-treating with chemicals
  5. Drying the strip
  6. Application of primer on one or both sides
  1. First curing oven (15-60 seconds)
  2. Cooling the strip
  3. Top coating on one or both sides
  4. Second curing oven (15-60 seconds)
  5. Cooling to room temperature
  6. Rewinding of the coated coil

As you can see, the process is intensive and thorough. This production line allows for a consistent, accurate, and high performance coating application.


Coating types for coil coating and the end uses

For a process so finely tuned, there is a remarkable degree of flexibility with regards to coating technologies. The metal sheet can be coated with your specific end use in mind. Available coatings include polyesters, polyurethanes, epoxies, fluoropolymers, and more. These can also be applied with different finishes, from matte to high gloss, and textures like wrinkle.

Polyvinylidene fluoride (PVDF)

washing machine with coil coating

Polyester coil coating is suitable for metal for appliances such as washing machines.

Also called 70% PVDF (from the percentage of resin), polyvinylidene fluoride is a high performance fluoropolymer coating which is particularly used for architectural applications. Though known for their non-stick properties, fluoropolymer coatings bring a host of other benefits due to their stable and strong chemical structure. They are chemical resistant, corrosion resistant, and temperature resistant as well as having superior color and gloss retention due to its UV stability. In short, they provide excellent protection against weathering, sun exposure, chemicals,  heat, and other harsh outdoor elements.
APPLICATIONS: Architectural and residential metal roofing systems, composite and insulated metal wall panel systems, curtain walls, siding, canopies.

Polyester

Polyester is available in a range of formulations which means there is diversity in its properties. This is usually indicated by cost – the lower the cost, the less durable the coating. Polyester is an extremely hard and tough coating, used across a wide range of heavy-duty surfaces. When you combine this with the lower cost, it is clear why polyester is a common choice for warehouses and industrial or storage buildings. Polyester is also used for appliances due to its superior scratch resistance, great flexibility and formability, and stain and dirt resistance.
APPLICATIONS: Heating, ventilation, and air conditioning (HVAC) equipment, garage doors, warehouses, appliances such as refrigerators, freezers, water heaters, washers, and dryers.

Silicone modified polyester (SMP)

Silicone modified polyester is created by adding silicone resin to a polyester resin coating. The resulting coating is somewhere between polyester and PVDF, with the hardness of polyester and a fade and chalk resistance more comparable with that of PVDF. SMPs are more scratch and abrasion resistant that PVDF, meaning they are able to withstand rougher handling conditions. They can be modified to have an expected lifespan of up to 20 years. SMPs are durable, and have good weatherability, color consistency, color and gloss retention, and resistance to chalking, fading, and scratching.
APPLICATIONS: Commercial and residential metal roofing, agricultural and industrial building components, siding, gutters, and downspouts.


The biggest players in the coil coating industry

The world’s leading coil coatings producers are AkzoNobel, Axalta, Beckers, Valspar, and PPG Industries. AkzoNobel has been expanding its coil coating operations by buying the Industrial Coatings business from BASF in 2016 including their manufacturing plant in the United Kingdom. Globally the biggest user of coil coated metal is the building and construction industry, accounting for 75% of the global market in 2017.

If you are interested in what coil coating can do for your project, our experts are here to help. Get in touch through the button below or through our contact form and let us know about your coating needs. Then we collaborate with our coating partners to determine the best coating solution for your project. Below is a selection of the coil coating companies in the UAE.

Coil Coating CompanyLocationServices Offered
CoolCoatingPO BOX : 656, SharjahOffers a wide range of can and coil coatings for the needs and requirements of the construction, building and packaging industry
Modern Ajman Steel Factory LLCPO Box No. 1760, AjmanOne of the leading suppliers of Galvanized, Cold rolled, and Hot Rolled Coils/Sheets and all types of structural steel in United Arab Emirates and Middle East market
MPIL OVERSEAS TRADING DMCC30-H, Silver Tower, Cluster I – Jumeirah Lake Towers, DubaiMPIL has a state of art coil coating line to meet every requirement of customer needs
Oasis Coils & Coatings L.L.C.Buldg No 98, 26th St, Al Quoz Industrial Area 4, DubaiSpecialist in the manufacturing and coating of HVAC coils
Spectrum Industries LLCPlot No: 597-619, Dubai Investments Park – 2, DubaiSpecialists in the production of Coil, Extrusion and Can coatings, including PVDF coating
Sunrise Metal CoatingDubai Investment Park, Jabel Ali, DubaiProduction and supply of high quality pre-painted coils in a range of metals and coating types
United Metal Coating LLCDubai Industrial Park, P.O. 181837, DubaiLeader in the coil coating industries in the Middle East region with an annual production capacity of 25,000 MT Pre-Painted Aluminum coils / 70,000 Tons of Pre-Painted Steel Coils