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Coil Coating

Metal Coating: Solid and Looking Good

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MCN Editor Beth Gainer Coating, such as prepainting, helps protect coils from a variety of conditions while producing aesthetically pleasing products.

Prefabrication coil coating is a big player in the building and construction arena. These applications demand coils be treated to protect against inclement weather and other harsh conditions. Whether solely for corrosion protection, for aesthetic reasons, or both, coil precoating and its technology are ever-evolving.

Chemcoaters LLC is a metal finisher in Gary, Ind., serving OEMs and service centers who use OEMs. Chemcoaters has developed an innovative in-house, water-based chemical treatment called InterCoat ChemGuard, which is applied onto zinc-treated metal surfaces. As the chemical treatment leaches into the zinc, a new layer of protection is formed over the substrate. 

Most other companies’ coating lines have gas-fired ovens and accumulation towers. However, Chemcoaters’ curing occurs in an infrared oven. “We are actually a 600-foot stop/start line so when our coil falls off, our line actually stops until [staff] put on the next coil,” says Technical Sales Manager Ted Jarosz. “If we were to have a traditional gas-fired oven, whatever was inside that oven would burn because of the heat.”

Another form of corrosion resistance is found by prepainting coils. While the prepaint process does not change the properties of the underlying steel substrate, “it does add an additional layer of corrosion protection to the finished product,” says Troy Brooks, vice president and general manager of Nucor Steel Arkansas in Blytheville, Ark. 
According to Richard King, product manager for Steelscape LLC, Kalama, Wash., prepainted metal offers durable and cost-effective material options for end users. “The paint does add more than color. It can provide an additional barrier against corrosion, can improve the metal’s formability and can improve metal’s resistance against the effects of certain chemicals, such as industrial gases.”

In fact, when properly applied, treated and cured, paint can tightly bond to the base metal, extending its lifespan in many applications. King says each prepainted coil must undergo stringent ASTM standard test procedures, compared with field-painted metal, which is only visually inspected. Prepainting can lead to “a robust, flexible finish that can be formed into product shapes such as roof profiles without cracking or peeling,” he says, adding that because the metal is formed after painting, manufacturers need not inventory finished products.

Coil prepainting “is applied in a continuous, automated and controlled process,” says King. “With a controlled environment, precise application and tightly bonded adhesion, less paint is needed to achieve a robust finish, improving paint efficiency and lowering the end price for product users.”

Jeff Williams, vice president and general manager at new Carlisle, Ind.-based EDCOAT LLC, agrees the right environment helps yield high-quality prepainted products. Seventy percent of the material EDCOAT processes is aluminum, with the remainder being steel. The company precoats metals to be used in residential applications, such as soffits, roofing and siding.

“The biggest advantage of coil coating is that we’re the last point in the supply chain in which [the metal] is flat, so by painting it in a flat condition, we’re able to control things much better,” Williams says. “Being able to clean, pre-treat and prime the substrate better helps it off to a good start.” He adds that 80 percent of coil coating benefits occurs during this process because there are no corners or holes to worry about. “We are controlling paint better than the mills can control the steel thickness or the aluminum thickness,” he says. 

So agrees Laura Lanza, sales director, building and construction products at Atlanta-based Novelis. Lanza agrees the keys to a quality product are the “controls that are virtually impossible to attain with most other painting processes. Dealing with a flat sheet allows for mechanical cleaning in addition to the spray cleaning.” She adds, “The flat sheet also enables excellent control of coating weights of both the pretreatment and the paint to within a tenth of a mil or less, depending upon the equipment and the paint system being applied.” She says that today’s coatings can make a product “more UV resistant, more graffiti resistant, more thermal emitting and enhance water tightness.”

Applications for prepainted metal have evolved, thanks to ever-changing technology. “Paint companies are constantly developing technology that improves the hardness, flexibility and exterior durability of their products. This is especially important since 75 percent of what we do in our industry is produce materials that go outside in a building construction environment,” says David Cocuzzi, technical director of the National Coil Coating Association, Cleveland. “UV durability and resistance to rain and all the other elements are paramount.”

Novelis is exploring the use of solar reflective coatings for building exteriors and “working toward coatings that can be used in all climates to help regulate indoor temperatures by emitting the right amount of UV energy depending on climate,” says Lanza. She adds that prepainted coils are environmentally sustainable. “Unlike brick, cement, wood and many other building materials, prepainted metal can be recycled without loss of quality,” she says. “Aluminum and steel continually recover their original performance properties, even after multiple times of recycling. In fact, about 95 percent of the prepainted metal that is used in buildings is collected and recycled.”

Prepainted metal offers abundant options. “You always hear about disruptive technology, typically when you’re talking about electronics,” says Cocuzzi. “Prepainted metal is actually the disrupter because a fabricator can order a painted coil of any color and texture and then fabricate it into any part that he wants, and he doesn’t have to bother with a painting process because it’s already been done by the coil coater.”

Indeed, painting metals before they are fabricated helps lend a long, attractive life for commercial and residential applications. In fact, today, structures such as roofs, siding products, gutters and garage doors never looked – or functioned – so good. 

Special Effects 
Today’s prepainted-metal technology provides many aesthetic options. “Traditionally coil coating finishes offered a kaleidoscope of glossy, solid colors. New technology builds upon this to offer paints with texture, paints with translucent finishes for dynamic light play and matte finishes,” says King. “The technology used to apply paint has also evolved to include the use of specialty paint application processes to create a wide range of painted effects.” For example, the coater can apply paint effects such as an overall look of woodgrain or stucco.  

Prepainting coils is an attractive field from an aesthetic and financial standpoint. For instance, in December, instead of building a brand new paint line, Nucor acquired the Precoat Metals facility in Armorel, Ark. Near the Nucor Steel Arkansas sheet mill campus, the facility is now known as Nucor Coatings. Most of the time, Nucor Steel supplies the substrate, but the company also processes non-Nucor material. “We will continue to support those supply chains,” says Brooks. “Nucor Coatings will support both single invoice and toll processing programs.” 

The already-existing paint line offers advantages over building a new facility. “Buying this paint line will greatly accelerate our entrance into the painted products market, and we will do so with existing capacity,” says Brooks. “Through this acquisition, we get an experienced team who are familiar with paint line operations, scheduling and inventory management, as well as an existing book of business. We can hit the ground running.” 

This paint line will help Nucor diversify its offerings for construction, HVAC systems, garage doors, lighting and transportation. “Adding this capability is another way we can serve our customers by providing a product they need,” notes Brooks. “We will also have greater control over quality and on-time delivery.”

While applications such as walk-in coolers, truck trailer bodies and appliances are strong markets for prepainted metal, vast applications exist in the building and construction industry, with technology applied to garage doors, soffits and siding. The pandemic has made homeowners shelter in place – and that has helped turn a profit for many companies such as EDCOAT. “[Homeowners] look around the house and say, ‘I could use some new gutters,’ and ‘That siding is looking a little banged up; I think it’s time to change it,’” says Williams. “Our business is up tremendously.”

And for homeowners, metal is raising the roof – literally. In residential construction, metal roofs continue to grow in popularity.

Agricultural, industrial and commercial structures have historically had metal roofs, but recently, the residential roofing market has witnessed a huge demand for this product. “Twenty years ago, residential roofs might have had a one to three percent market share. These days we’ve got maybe 12 to 13 percent market share,” says Cocuzzi. “Now that may not sound like it’s a huge jump, but it’s a giant market.”

He acknowledges that asphalt shingles still dominate the residential roofing market. Although homeowners might be initially reluctant to pay for pricier metal roofs than shingle roofs, the life cycle of metal roofs justifies their price. “The lifetime of a metal roof is 40 or 50 years, whereas with asphalt shingles, it is more like 10 to 20 years,” he says.

However, this industry is not without its challenges. According to Williams, metal availability is a problem. “We’ve had some industry issues in the aluminum mills that have impacted supply greatly. We have various tariffs that have been installed that are reducing the flow of foreign metal,” he says. “Metal availability on the aluminum side is extremely tight. On the steel side, it’s been tight as well. The mills [and others] have taken capacity offline and have been slow to bring it back online, trying to bump up prices, and there are tariffs on imported steel.”

In addition, prepainting has its own issues. “Given the size of coils, they typically require established supply chains with specialty handling equipment, which can limit supply chain changes,” says King. “However players in the supply chain are always seeking to improve process efficiency and to improve inventory turnover.” To help do this, businesses are using automated cranes to manage inventory flow and turnover “while reducing inventory floorspace, improved logistical equipment including custom rail cars and handling equipment to maximize load limits,” he adds.

“Other developments have included the expanded use of RFID and integrated information systems to improve the visibility and communication of product flow between producers and customers,” he continues. “The availability of more economical manufacturing equipment that uses pre-painted metal for construction products, namely roofing roll formers, continues to expand the application and use of prepainted metal.” 

The top coat paint layer is applied to prefabricated metal. 
(Photo courtesy Steelscape LLC)

Digital Design Developments
U.S. coil coaters are able to print patterns on coils, but there’s an up-and-coming printing method, not yet commercially available in the country, that the Cleveland-based National Coil Coating Association’s Technical Director David Cocuzzi describes as “phenomenal” and “one of the most intriguing developments.” 
This method involves digitally printing patterns on top of prepainted steel and aluminum. This approach is similar to that of an inkjet printer, but on a very large scale. The print options are only limited to the imagination of the designer.
The idea behind digital printing is conceptually straightforward. “It’s a matter of simply creating the electronic file and plugging it in, then running a certain number of feet, or a certain number of pounds of metal,” says Cocuzzi.
“You can shift from one pattern to another on the fly because electronic files are just being swapped,” he says, adding that paint suppliers would help with the production of the colored inks and perhaps the protective clear coat. “The inks themselves need to be formulated with pigments and resin chemistry that is very durable in sunlight, and usually there’s a clear overcoat to offer even better protection,” he says.
Digital printing “has left the proof of principal stage and is now entering the commercial stage,” he adds. 
While using the digital printing mechanisms seems easy, Cocuzzi still predicts a learning curve. “When you finally go to prime time, that’s when you find out what the bugs are,” he says. “It all looks good on paper, but when you make the installation, then you start working with particular issues that you never dreamt would be a factor.”
Despite the unknowns, and the fact that digital printing devices may be quite expensive, this technology is a huge development for countless design possibilities. Coil coaters will have another arsenal of tools at their disposal – and customers will have a plethora of choices.


Protecting Coils with Polyurethane 
Protecting coils is vital to Bruce DeMent, CEO of Kastalon Polyurethane Products, Alsip, Ill. The company manufactures polyurethane products to protect coils’ surfaces. “The surface finish is critical and needs to be protected,” he says, adding that Kastalon’s mandrel sleeves protect the coated coil from metal-to-metal contact with the mandrel drum. Furthermore, the company’s mandrel sleeves help prevent common processing damage, such as reel breaks and head-end damage.
“Our sleeves help prevent coil slippage and increase the overall efficiency of the processing line,” says DeMent. “Our proprietary chemistries and manufacturing capabilities allow for Kastalon mandrel sleeves of virtually any size and hardness, and specific to each customer’s requirements.”
Kastalon coil floor pads protect coated coils during storage as well as serve an organizational function for the production floor.  The pads are available with and without fluid-collection capabilities. In addition, rollers used in uncoilers or surfaces that support the coil are covered in polyurethane so the surface where each coil is resting upon doesn’t dent the coil.
Kastalon also manufactures polyurethane devices in coil material handling and storage. “Everything that touches that coil can be covered with polyurethane – from a c-hook to the [forks] of a forklift truck,” says DeMent. 
While polyurethane is more expensive than rubber, the former lasts 10 to 20 times longer than the latter. In addition, polyurethane requires less maintenance than rubber, according to DeMent. The equipment is operating longer and doesn’t have as much maintenance, resulting in cost savings.
“Polyurethane is extremely durable and yet cushions the coil so that it doesn’t get edge damage,” says DeMent. “The polyurethane floor pads protect coils by keeping them off the floor.”
“Everything is protected.”