Thermoforming corrugated board has been tried before, but it wasn’t commercialized. So says Thomas Strong, general manager for NaturePak, the company that worked with Racine Danish Kringles to develop the “Corru” tray used for RDK’s kringles. Strong confirms that RDK is the first company to use the Corru tray.
“We bought a thermoforming machine for [the kringle tray application],” Strong says. “The company that makes the machine is the same company that had tried to market thermoformed corrugated before, but at this point we cannot divulge who it is. There’s no other machine like this right now,” he believes.
Strong explains that the machine is specially modified for the corrugated board. The overall process, however, sounds much like that of plastic thermoforming. After proprietary pre-treating that involves adding moisture, the board is placed onto the forming section of the machine, which is equipped with male and female tooling. Heat and pressure create the tray, which has a 7/8” depth of draw. Operators stack trays, which are placed into a drying tunnel. Built by NaturePak, the tunnel helps remove moisture from the trays. Excess moisture could lessen tray performance. Nested trays are shipped to RDK.
NaturePak uses different corrugated suppliers to create the 200#-test, E-flute blanks. The 42-33-42 board includes white liners on both sides. The corrugated supplier flexo-prints the nonfood-contact side. Spectra-kote® (Gettysburg, PA) adds its grease-resistant coating to both sides of the board. A heavier amount of coating is applied to the food-contact surface to withstand the kringle’s high butterfat content. The coating does not completely go through the blank. Printed, coated blanks then go to NaturePak for thermoforming.
The R&D process for the kringles tray was truly a joint effort. “Racine Danish Kringles has been part of this development process,” Strong explains. “Mike Heyer [RDK’s owner/president] was instrumental in helping us develop the properties their company needed from the tray, mainly its strength. We went through some hurdles in its design. Mike took a chance on us and on this idea. He was committed to making it work.”
See the main story that goes with this sidebar: Kringle tray’s a sweet success