Lights-out inmold decorating

Cascade Engineering’s Container Group rarely does anything small. It runs a press it calls "The Big Girl," for instance. She’s a 9000-ton Battenfeld—the largest injection press in the U.S.—and she can mold big parts, like 2-yd-long HDPE waste containers, each a 116-lb shot. Cascade plans to install an even bigger press. Meanwhile, the Container Group also has big plans for inmold decoration.

"Imagine permanently decorating the entire side of a 6-ft-long container with a vibrant color poster. It would look like a billboard," says Gary L. Kaminski, the Container Group’s process engineer.

The group has started with a 1760-ton two-platen Ferromatik Milacron hydromechanical press with an integrated automated electrostatic inmold decorating system from Geiger Handling USA.

The cell molds 4.25-lb HDPE lids for 96-gal waste containers. Lids decorated with attention-grabbing, bilingual warning labels that will never come off are ejected onto a conveyor.

"We used to cut lettering into the tool, but the warning was in the same color as the plastic and was as difficult to see as it was to read," Kaminski explains. "We tried hot stamping, but adhesive can be costly, and if it outgasses you have to manually smooth out the bubbles. We’ve added design freedom, reduced tooling costs, increased output, and eliminated a secondary process with Geiger Handling’s help, all with better labels that last."

Adding Permanent Value
Cascade guarantees its products for 10 years. They have a tough service life ahead of them, so Cascade contracted with an independent engineering and testing lab in Grand Rapids, MI called Entela to determine just how permanent the permanent labels are.

Entela uses its own patent-pending Failure Mode Verification Testing method. FMVT anticipates improper product use and identifies the root causes of structural and mechanical problems, while conducting accelerated tests under a number of harsh conditions. The decorated lids passed with flying colors.

"Before, when the mold opened, the part just fell out. We see that now as waste," Kaminski says, adding that automation has freed his people to do tasks more meaningful than smoothing out bubbles. "What could be more value-added than that?"

"Imagine, a recycling container molded in postconsumer resin with permanent instructions on what type of recycling waste goes into the container—plus a phone number and a Web address for questions," Kaminski concludes. "For the life of the product, people could find out how to use it. So, value is added for the ultimate customer, the consumer."

Electrostatic decoration: How it worksGeiger Handling USA offers a one-step, shoot-and-ship inmold decorating process. Typically, a robot equipped with a static charger on its EOAT (end-of-arm tooling) removes a flat, die-cut, preprinted decoration from a holding station beside the press. The robot precisely positions it slightly in front of the open mold face. The charge unit is energized and runs ions onto the back of the decoration to ground, generating a static electric field.

In the blink of an eye, the decoration leaps from the robot’s EOAT to stick firmly onto the mold face. If part design warrants more accurate placement, the robot can press the decoration into place while charging it.

The mold closes and the substrate resin is injected behind the graphic, fusing it into the part as it is formed in the cavity. The decorations, which can be diecut to decorate complex surfaces, reportedly are compatible with all plastic resins, conform to mold textures, and shrink with molded parts. Mold modifications and secondary finishing are unnecessary. Also, surface appearance imperfections can be permanently hidden beneath seamless decorations.

Pinnacle Products Group Ltd. (Dayton, OH) supplies the colorful, preprinted decorations in custom coatings and finishes, as does Serigraph Inc. (West Bend, WI). Static charge units—from suppliers like Simco Industrial Static Control (Hatfield, PA) and Tantec Inc. (Schaumburg, IL)—are capable of generating up to 50,000 volts of static charge.