By Olivia Cahoon
Part 2 of 2
Dye-sublimation (dye-sub) transfer printing requires the use of a heat press or calender to execute the sublimation process. While both devices are designed to transfer images to a substrate through heat and pressure, each sources heat through different methods.
Heat Press vs. Calender
For dye-sub transfer printing, a heat press or calender may be used.
A flat heat press presses fabrics, non-curved objects, and pieces such as mouse pads or doormats, as large as the heat platen and table allows. In large format, this size starts at 30×40 inches and can exceed 10×10 feet in a custom configuration, shares Matt Gusse, VP sales and marketing, Advanced Color Solutions (ACS). The device may be set up manually, semi-automatically, or fully automatic and driven with air.
Heat presses are available in many sizes and designs. Michael Stark, sales and marketing manager, Joto Inc., says that unlike a calender press, heat presses can also be used to transfer images to mouse pads, glass, ceramic tiles, and HD photo panels.
Heat presses use aluminum heated by an electric heater, offers Catherine Lou, sales manager, Eastsign Inc. “So, the temperature is not even across the plate,” she admits.
A rotary or calender heat press is designed to affix heat or cure printed fabrics in three ways—continuously from a roll, sheet, or cut pieces, explains Gusse. “You can invest in a machine which handles all three applications or in one that just presses roll to roll (R2R),” he adds. Calenders use two drums, either heated with oil or an electrical IR rod inserted in the drum. “The speed of these machines is dictated by the size of the drum and consistency of the heating element.”
The calender process includes feeding material over or under a rotary drum. Widths vary between 45 and 122 inches, with large custom orders possible. Drum diameters vary from eight up to 55 inches and larger, admits Dan Kane, marketing manager, graphics, Royal Sovereign. “Drum size is related to speed. The larger the drum, the faster production speeds can be achieved,” he continues. However, calenders are limited to only flexible media making them ideally suited for flags, banners, and apparel production.
Calenders consist of a series of hard pressure rollers that finish or smooth a sheet of material like paper, textiles, or plastics, adds Marty Silveira, VP, DigiFab Systems, Inc. It’s also used to form plastic films and apply coatings. These devices are designed for R2R sublimation, typically for textiles.
Heat presses/calenders consist of a variety of features, but the most important include the device’s size, heat distribution, and textile alignment.
When determining heating equipment width, there are two considerations—the size of the sublimation printer and the future requirements to what will be produced, says Stark. “Often a decorator will choose to purchase a calender press that is wider than their current printer in anticipation of growth and changes in the market.”
Heat presses are available in two options, small format and large format. According to Stark, it’s always advisable to select the heat press size based on the type of items to be imaged. “It is recommended that your press has between 0.5- and one-inch margins around all four sides.”
He also advises print service providers (PSPs) ensure the press is well constructed and can produce adequate pressure. “There are many inexpensive presses on the market, they are generally only suitable for the hobby market,” he explains. Additionally, presses should have at least one year warranty and five years on the heating element.
Large format heat presses should distribute even pressure and accurate heat across the entire platen area, recommends Cris Saunders, director of sales and marketing, Insta Graphic Systems. “Heat recovery also must be quick and within five degrees of the set temperature. Failure to maintain heat means inferior applications,” he explains.
PSPs should also pay attention to transfer paper and textile alignment. John Selfhout, manager marketing and sales, Klieverik, believes a sharp print is the result of a high resolution design and printer, as well as a transfer process where the alignment between the paper and the textile is perfect. In a heat press, this process is uncontrolled when the press is opened. “Upon lifting the top-section textile, the paper may be lifted simultaneously and in a split second the gassed inks deposit on the textile, destroying the sharp image,” he explains.
The use of sticky paper is the most common way to limit this effect. On a continuous belt calender, Selfhout believes the alignment should be perfect as well. Here, he says the belt’s steering and pressurizing are the key issues to look at. “A discontinuous belt steering—waiting till the belt wanders to one side of the machine and then counter action to direct it to the other side—may result in a lateral movement of the textile versus the paper,” he offers.
According to Chase Pender, marketing manager, Supply55, Inc., PSPs looking for heat presses and/or calenders should also consider the device’s available parts, ease of training, power requirements, and if the price meets the production requirements of the application.
Electric vs. Oil
Rotary/calender heat press equipment is available in two heating element configurations—electric and oil. Silveira says oil presses are recommended for use in large production. “The cost of an oil heat press is higher than an electric of a similar drum size, so it’s not a necessary expense to make when pairing speed with most digital equipment,” he explains.
The true benefits for oil are apparent with larger drums. Smaller oil drums, for example those of eight inches in diameter, contain less than two cubic feet of oil but still require a longer heat up and cool down than an electric press of even larger dimensions, which turns into higher power consumption, shares Silveira.
According to Gusse, electric calenders offer a lower cost investment, quicker warm up and cool down, simplicity, and the ability to handle most applications with ease. On the other end, oil configurations provide consistency, a variety of size options, efficiency, and the ability to better handle thicker materials.
Available Heat Presses/Calenders
Depending on the application, operator’s expertise, and shop volume, PSPs offering dye-sub transfer printing have choices for heat devices. This includes heat presses and calender units in a variety of sizes and heat configurations.
ACS distributes the Practix OK-10CP ten-inch oil drum for R2R or cut parts. Released in 2016, the device handles materials up to 66 inches wide at 2.4 yards per minute with a 40 second dwell time. “CP allows for cut apparel pieces or many pre-made promotional items to be pressed continuously for maximum volume,” says Gusse. It features a compact size for production output, state of the art controls, and a three plus year warranty. Depending on add-on options, the Practix OK-10CP is available from $35,000 to $45,000.
DigiFab’s DigiHeat calender press was released in January 2014. It is a rotary and flat device using both electric and oil type heat with drum diameters from nine to 22 inches. The device handles widths up to 136 inches and reaches speeds up to ten linear feet per minute. “DigiHeat presses are manufactured to provide customers high-quality output, built with quality components and heating elements, all within a compact steal frame in order to not limit where these machines can be installed,” explains Silveira. DigiHeat models maintain a two year warranty and are backed by a network of service technicians. Price varies by size, speed, and add-on options.
Released in August 2017, Eastsign offers the BOT-1742-H. It handles widths up to 64 inches and produces six feet per minute. According to Lou, the device features a full oil drum to provide stable transfer, interactive touch screen control panel, conveyor built, and technical support. A bigger drum is available for high-speed transfer and fits into a small working space. The BOT-1742-H is available for $29,000.
Insta Graphic Systems’ Insta 1020 is a large format dual shuttle press. It features a 39.4×47.2-inch upper platen, an automatic reciprocating dual tray system, and two air cylinders to produce pressure. The press is designed to maximize resources while maintaining exceptional quality. It is fully automatic and distributes even pressure across the platens.
Joto provides a variety of heat presses in narrow and wide format sizes. Its large format heat presses include the Joto Automatic Double Station Shuttle Press, Automatic Single Station Shuttle Press, Dual Shuttle Press, and Pneumatic Large Format Heat Press. Released in February 2017, the Joto Dual Shuttle Press features a space-saving design and 59×98-inch maximum width. It is an air operated device with two stations on one side. The Joto Dual Shuttle Press is available for $32,995.
Klieverik provides the GTC series belt calenders and GFC series beltless dye fixation calenders. The devices are available in widths up to 5,100 millimeters ranging in speed from 70 to 1,920 square meters per hour. “Klieverik offers the best solution for temperature consistency and web handling, in an industrial execution suitable for 24/7 production, with a support that matches exactly that ambition,” shares Selfhout.
Royal Sovereign has a variety of products ranging from 45 to 122 inches with oil drums ranging from ten to 34 inches. Its most popular model is the PX-181F part of the InPress series of calenders, released in April 2015. With a 67-inch maximum width, the device operates up to 3.9 feet per minute with a 30 second dwell time. According to Kane, it features a standard cut piece production table, ten-inch oil drum, universal unwind core adapters, anti-ghosting mechanism, 72 percent belt coverage, and an over-the-drum circuit.
Released in 2013, Supply55’s Guardian Calender handles media up to 67 inches in width. It produces 71 yards per hour at a 40 second dwell time. The Guardian Calender features a 208 volt single phase power Quartz infrared heat element, a Nomex felt belt with a Kevlar reinforced center, and support for sublimation paper transfer or direct print applications. “Fast warm up and cool down times allow the PSP to maximize production uptime,” advises Pender. The Guardian Calender is available for $29,995.
For dye-sub transfer printing, PSPs have a variety of heat transfer options including heat presses and calenders that utilize electric or oil drums. To ensure consistency, it’s important that PSPs invest in quality solutions suitable for their printing environment.
Sep2018, Digital Output