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Tech Watch

High-Speed Foil Fusing

by Jen Clark

February-March, 2014

A process once used for making samples has become a means to efficiently personalize Christmas cards, graduation announcements and other items featuring variable data with foil, without the use of a die. High-Speed Foil Fusing™ (HSFF™) from Therm-O-Type Corporation, Nokomis, FL, speeds process times, minimizes wasted foil and localizes foil placement.

“It’s completely unique,” Chris Van Pelt, president, said of the technology. “You’re applying foil without a die, and you can apply variable data to each page. It’s very inexpensive and can be used with most existing platen foil stamping equipment.”

Traditional foil fusing uses a series of heated rollers, like a laminator. Paper imprinted with toner is run through and the combination of heat and pressure causes the foil to adhere to the toner image areas. While foil fusing isn’t a new concept, Van Pelt said there are reasons why people don’t utilize it. “Existing foil fusing equipment can be slow and may waste foil,” he said. “It typically runs at less than 400 linear feet per hour and draws foil the full length of the paper regardless of the foil image area. It only can be used on certain, smooth finish paper stocks, and there is no way to localize the toner image areas where foil would, or would not, be fused.”

With HSFF, foil is fused to toner image areas that have been printed on paper with a laser printer or copy machine. “The HSFF process was designed as a solution to allow customers to run much faster (up to 4,000 impressions per hour); to run textured papers, as well as smooth-finish papers; and to only advance the amount of foil needed,” he said. “A simple makeready process can determine where the foil should stick.”

The system is well-suited for small-quantity products. When used for personalization, Van Pelt said, it is possible to run sheets with a different personalization on each sheet while foil fusing at high speed. “Because HSFF does not use a metal die, any texture in the paper will not be crushed flat by the foil fusing process,” he said.

Technical details
HSFF foils are manufactured to adhere to toner, but foils that work with traditional foil fusing often do not work with the HSFF process. A wide selection of metallic colors; pigments, including white; metallic glitters; metallic and transparent holographic patterns; and security foils are available for HSFF.

Thermal transfer plate. HSFF requires heat and pressure to create a foil image. The Thermal Transfer Plate (TTP) is the surface used to apply heat to the foil, toner and paper. This plate is .25" thick and replaces the die on the chase. TTP material is a composite with a metal backer with a high temperature, compressible, synthetic coating facing the foil/paper. To maximize HSFF production, Therm-O-Type recommends the TTP be mounted on a chase configured with mounting holes. A honeycomb-style chase is not recommended for HSFF when running at higher speeds, because it produces lower heat density/transfer.

Bottom makeready material. The most confusing issue with HSFF is that even though the TTP and foil may cover different toner image areas on a sheet, the HSFF process allows foil to be selectively applied to certain image areas without affecting the surrounding toner image areas. The use of Bottom Makeready Material (BMM) provides the means to localize where pressure is applied to the paper and foil against the TTP. By cutting and applying the self-adhesive BMM to align only with the toner image areas where foil is to be fused, pressure can be selectively applied to these image areas. Therm-O-Type recommends that HSFF makeready be mounted on a special base sheet to allow a makeready to be used repeatedly.

Thermal insulating material. Under certain circumstances, HSFF foil may adhere to toner outside the areas defined by the BMM. This can be caused by various factors, including paper flexing during the HSFF impression cycle or toner image areas that are very close to where foil is being fused. Applying Thermal Insulating Material (TIM) to the TTP creates a thermal barrier that eliminates foil fusing in these areas. TIM is a thin, self-adhesive, high-temperature insulation that can be cut with scissors and applied to the TTP to stop foil from fusing to toner outside the areas defined by the HSFF makeready.

Special considerations. There always must be some gap between toner image areas when one image area is to be foil fused and the adjacent image area is not. This gap will vary depending on the registration accuracy of the printer applying the toner to the sheet. Paper surface finish is not an issue when using the HSFF process. In fact, papers with very deep textures can be foil fused with the HSFF process, provided the laser printer can apply toner within the textured surface. As with heated roller foil fusing, HSFF is not compatible with all toners. N

For additional information on the HSFF process, makeready material, set-up procedures, fusing foils and films, contact Therm-O-Type at 800.237.9630 or visit www.thermotype.com.