Thermoforming, sometimes called vacuum forming, has been around the sign industry for many years, and some consider it something of an art form. It’s a manufacturing process in which a plastic sheet is heated to an optimal forming temperature and—using vacuum and pressure—is formed into a 3-D part. In its simplest form, an oven is used to heat small cut sections of plastic sheet and stretch it over a mold using a vacuum. From the suction of the vacuum, the plastic is drawn up to the contours of the mold, giving a sign a 3-D look and feel. This could either be a logo, lettering or just a plastic pan face.
In the sign world, thermoforming is mostly employed in the creation of lighted 3-D pole, hanging and storefront signs, but can be used for packaging, P.O.P. and prototyping applications as well. From a marketing point of view, thermoforming can provide a significant impact on the final look of a finished product.
Plastivac produces fully decorated thermoformed sign faces from Plaskolite SG-10 modified acrylic and Lacryl paint. (Image courtesy of Plastivac Inc.)
Imaging for Thermoform Applications
Producing an image on a thermoformed sheet can be accomplished a number of ways, including hand painting, applying graphic vinyl, screen printing and even direct digital printing. Sometimes the image can be applied after the sheet is heated and formed, and sometimes it needs to be applied before. However, you need to alter the image to compensate for the amount the plastic will be drawn (stretched) over the form in order for the image to appear normal after thermoforming.
This type of “distortion printing” onto raw sheet stock for thermoforming has been a niche market and it has traditionally taken extensive knowledge and skill to become efficient and profitable with the process. This knowledge was mostly developed by screen printers, derived by trial and error working with the process over a number of years. Because of the intricacies involved, there are only a small number of sign shops that specialize in this business. However, thanks to recent advances in proprietary distortion printing software, improved media and processing techniques, these sign makers are now able to easily create these products by utilizing virtually the same standard job procedures they traditionally use.
The traditional way to add graphic elements to a thermoformed sign was to paint them. One of the pioneers in this market is Plastivac, Inc., a Buda, Texas-based sign wholesaler that has been supplying custom vacuum formed sign faces to clients since 1980. “We produce fully decorated faces with embossed copy, painted pan faces using Plaskolite SG-10 modified acrylic and Lacryl paint that can be matched with any PMS or vinyl color chart,” says company president Richard McCormick. He adds they also make white pans that are manufactured with Crylex DR white modified acrylic, from those a sign company can apply the vinyl or the digital graphic to the face when they install the sign.
Painting by the Numbers
“I have been making sign faces for over 30 years and painting them is still the best way to go,” McCormick says. “The painted faces will last anywhere from 20-30 years, where the digital prints and vinyl will last 4-5 years before they start to fade. We paint all the graphics on the second surface so the paint is protected from the elements. I still see sign faces that I made 25 years ago that look great. The colors don’t fade or turn yellow.”
Spartech offers a rigid UV-stable thermoplastic sheet called WeatherPro SG that is intended for applications in which irregular custom shapes are required, such as this channel letter facing application. (Images courtesy of Spartech Corporation.)
McCormick says they work with a large number of sign companies from all over the country. “We only make the sign faces; that’s all we do. These types of lighted signs are made for the outdoor locales such as service stations, restaurants and grocery stores.”
He says that the sign companies will send them the digital artwork and using their software, they will design and build the mold which will make the pan face. “We then cut out the letters for the sign with our CNC router and then we nail those on the front of the mold to emboss the letters, thus, giving it the raised letter effect. For painted signs we use a clear modified acrylic. It holds up in the sun a lot longer than other materials. Acrylic possesses the rigidity essential for signage use. Its uniform composition and glass-like sheen are well-suited for light transmission and color rendition. Acrylic resists fading and general discoloration. After we cut the plastic it goes into the 8' x 12' oven to heat to 300 degrees. When it’s hot enough, it is laid over the mold and vacuum formed onto the mold. After it cools it is trimmed to size then ready to be painted. There are only a couple of paints out there that are designed for this purpose and it takes an expert hand to apply them correctly,” he explains.
McCormick adds that text or graphics can either be back-sprayed to the second surface or vinyl can be applied to the first surface of the pan face. Pan faces can also be used as reader boards or changeable letter signs by adding tracks. They also can apply a digital graphic if needed and paint the rest depending on the logo and graphics.
“I’m seeing a trend where more clients are asking for vinyl instead of paint. In my opinion, vinyl is a short-term product for this application, and many of these types of signs are made to be long term. At the end of the day, I think paint will still be part of the equation for years to come,” he says.
In this example, a Harley Davidson logo is printed on a plastic rigid sheet using a UV-curing printer and special highly-elastic inks. The sheet is then placed over a metal form, and using heat and vacuum pressure, the plastic takes on the shape of the form. The end result is a printed, thermoformed sign.
New Trends in Plastics
“Polycarbonate, acrylic and impact acrylic are the materials that still dominate the outdoor sign face market,” comments John Hirsch, commercial development manager at St. Louis-based Spartech Corporation. Spartech is a leading producer of plastic products and has been serving the sign industry for all sign face applications for more than 50 years. “The terrific thing about plastics is the flexibility you have in designing a sign for a specific application. Plastics are extremely versatile. The array of properties available in this class of material is so vast; you should be able to find a number of them that fit an application. For instance, if you want to make a plastic that is weather resistant to sunlight, it can be formulated that way. If you want to make a plastic that is conductive, it can be formulated that way,” he adds.
One of the company’s top products is their SunGard Ultra Weatherable Polycarbonate sheet. “It’s an all polycarbonate weatherable sheet product that combines the extraordinary impact strength of polycarbonate with outstanding UV stability. SunGard is highly resistant to weathering, discoloration, surface haze, loss of impact strength and other properties after prolonged outdoor exposure,” Hirsch explains.
The company also markets Crylex Plus, an acrylic material for rigid formed sign faces when the conditions require both weatherability and impact strength.
“Crylex Plus provides the necessary toughness to withstand the typical abuses of sign fabrication and installation, yet retains its color, clarity and weatherability. It is clearly a superior sign material choice,” he adds.
Hirsch says that the advent of digital printing is also becoming a game changer in this area. “Digital printing is quickly moving into the thermoforming space” he says. “It’s allowing signs to be made on a custom basis much faster and provides an alternative to painting. Digital inks are also being perfected to last longer in outdoor environments. Ten years ago they wouldn’t last, but today’s inks last much longer than that. It’s an emerging evolution that is beginning to change the landscape of this marketplace.”
The other growth area he is seeing is the rise of thermoformed “Cloud” sign bodies, which in some cases replace aluminum ones. “Many logo signs are made in different shapes. In the past, to fabricate aluminum into a sign body with an irregular shape was time consuming, labor intensive and costly. The current trend is to thermoform a thermoplastic into the shape of that sign. Then you can put all lighting and transformers inside that thermoformed part, then you put a face on front and you have a sign. This is the niche that our new WeatherPro SG was designed to satisfy.”
“WeatherPro SG is intended for applications in thermoformed signage in which irregular body shapes are required. It is a rigid, UV-stable thermoplastic sheet. Combining a unique, proprietary UV-resistant surface with the ductility and high impact resistance of ABS (Acrylonitrile-butadiene-styrene terpolymer), WeatherPro SG is finding a home with thermoforming and fabrication into custom sign applications,” he concludes.
A sampling of some of Plastivac’s thermoformed sign face projects. (Image courtesy of Plastivac Inc.)
Digital Software Solutions
If you are printing graphics on a sheet to be thermoformed for signs, retail displays, packaging; graphic designers, as mentioned earlier, must take into account the optical distortion that will occur when the flat printed image is formed into a 3-D surface. In the past this was a hit and miss procedure. New software is helping take the time and guesswork out of this process. R&R Graphix is the U.S. distributor for a product from France-based Quadris, developers of Thermo 3D Suite, a pre-distortion software system that allows for graphics to be printed right onto a thermoformed object.
“We saw a need for thermoformed products that needed to have pre-distorted artwork before printing to achieve accurate end results,” says Molly Ryback, sales consultant and graphics manager at the Charleston, SC-based firm. The company also provides thermoforming out sourcing services.
“Thermo 3-D Suite offers a solution to companies who need to create and produce thermoformed parts to get the most out of, not only rich graphics, but also a maximum decoration area. It also allows designers and prepress operators to correct design distortions occurring while the plastic sheet is formed. To that end, it is based upon measurements and not some hazy calculation or simulation,” she adds.
Ryback points out the software allows for companies to systematically distort artwork for putting onto any type of product including signs, packaging, prototyping, consumer electronics, etc. “The software eliminates the need for any manual calculations or guesswork. We provide them with a smart grid that recreates a 3-D model for them right on screen. With our software you get it right the first try, which saves time and money.”
Four Step Process
She adds that using this software users now have any thermoformed product they want covered by a perfect artful design in only four simple steps.
“The first step is the reconstruction of a 3-D template of the object. Next is visualization of the original artwork on the 3-D template so you get to see how the design is impacted by the thermoforming process. The third step is an amorphous calculation and pre-distortion of the design to make up for the distortions. And, finally the creation of a 3-D PDF file so you can actually see how the final product will look. Basically, this new software helps turn a difficult, time-consuming distortion thermoformed project, into a straightforward affordable vacuum formed product,” Ryback says.
She reports that they just started distributing the software in U.S. in the past year and the initial response has been very positive.
“As far as I know, we are the only software company currently in the U.S. with this type of product,” she says. “It’s a perfect solution to make your product stand out. We are getting a lot of good feedback from customers currently using the software as well as new companies inquiring about it.”