By Melinda Tetreault
Part 1 of 2
Thermoforming is used in the creation of signage, but is also found in industrial markets like building and construction, automotive/transportation, and medical. The newest UV ink sets are flexible enough to be placed in a thermoforming device after being digitally printed to the plastic sheet. Cracking or distortion is minimized, if not eliminated, ensuring a quality finished product.
Relating Digital to Thermoforming
The process of thermoforming involves a plastic sheet placed in a thermoforming device—a vacuum forming heat machine—that stretches and molds to a desired shape when heated. When UV ink sets are used on the printed substrate they must be able to withstand the heat in the vacuum forming machine.
Michael Maxwell, senior manager, Mimaki USA, Inc., explains that “inks with ultra stretch offer no distortion or cracking, which allow for deeper returns. The combination of CMYK, white, and clear offers more potential on colored or clear surfaces increasing the application potential. Additionally, the fact that it is digital means the user can produce just in time to whatever size required.”
“In regards to the vacuum forming market, whether it be point of purchase, automotive, signage, or pan face applications, the message is clear—with the capabilities of these highly specialized inks and printers, the opportunities and economic benefits users enjoy are unlimited. Imagine producing products with minimum waste and with literally no set up time. What used to take days to print, paint, or spray can now be done in minutes, saving thousands of dollars every single day,” shares Michael Plier, director of ink business development, EFI.
According to Kaz Kudo, associate product manager, graphic systems division, Fujifilm North America Corporation, customers have produced beer tap handles and shrouds to suitcases with digital and thermoforming. “Digital is continuing to grow into different markets as technology advances. With requests for faster turnarounds and more customization, digital inkjet is versatile in achieving these needs.”
Thinking Beyond Conventional Methods
Screenprinting is traditionally used in conjunction with thermoforming. Graphics can also be painted or decaled after thermoforming occurs. Digital printing presents manufacturers with a third possibility, one that allows for smaller runs and reduces time consuming practices.
“Digital offerings in this space have common advantages to other sectors. They allow for personalization, one-off prints, and reduced lead time, waste, and stock holdings,” offers Phil Jackman, global product manager, digital, Sun Chemical.
Originally, thermoformed products were simply one- or two-color products, according to Jay Roberts, product manager, UV printers, Roland DGA Corporation. As more complex requests evolved and with the introduction of digital UV “shrink” inks, “this made it possible for designers to experiment with and test diverse types of designs, images, and graphics quickly, easily, and cost effectively.”
“Screenprinted thermoforming is traditional; however, this process requires careful planning so the thermoformed image distorts and stretches appropriately. Screenprinting setup is time consuming and requires careful planning since each color is separated and a screen must be provided for each. Some of the process is the same for digital, however digital offers a more unique approach in that the file can be calculated prior to printing with more ease, and any adjustments that may need to be made, can be done so without lengthy setup,” adds Maxwell.
Heather Rockow, UV business development manager, Kao Collins Inc., shares information on decorating thermoformed products after the thermoforming process. “Painting by hand or applying stickers are two of the methods used and can be time consuming and expensive, not to mention the additional inventory of materials that is required. Digital printing the flat surface before it is thermoformed is faster and less costly. It also offers the ability to print different images on various products during the same production run or duplicate a customer’s order at a later time.”
Jackman offers tips on what manufacturers should look for when deciding on a UV ink. The first is a good backing white. This is important in the case of clear signs, but it also needs to transmit a nice clean white when backlit. Second are highly lightfast pigments as thermoforming applications are often used outdoors in challenging conditions. Third is adhesion. These inks need to have good adhesion to traditionally challenging materials, such as acrylic and polycarbonate. Fourth is surface resistance, as the inks need to be stackable following printing. Inks must have the resistance to the pressures in the forming process and be stackable during the transportation process. Finally, long-term flexibility is needed to ensure the print’s performance long term, especially in cases where the temperature is known to fluctuate or prints are subjected to movement.
Digital and Thermoforming
Screenprinting and manual techniques are popular ways to decorate a thermoformed item. With the advent of digital printing and UV inks that offer stretch and flexibility, manufacturers in building and construction, automotive/transportation, and medical can implement faster processes for shorter runs.
“As the speed of the printing machines and the resolution of the printheads increase, more manufacturers of thermoformed products are looking at digital printing as a way to broaden their customer base and reduce cost,” explains Rockow.
The second article in this two-part series on thermoforming looks at available digital UV inks and provides information from a sign company working with thermoforming.
Oct2018, Industrial Print Magazine