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Rib-less PET bottle prototype problem used to differentiate product

When Tom First, founder of bottler O Beverages LLC, received prototypes of the 17-ounce rib-less polyethylene terephthalate (PET) bottles from Amcor PET Packaging, he was astounded to see the bottles'...


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March 1, 2007 by Canadian Plastics



When Tom First, founder of bottler O Beverages LLC, received prototypes of the 17-ounce rib-less polyethylene terephthalate (PET) bottles from Amcor PET Packaging, he was astounded to see the bottles’ grainy surfaces.

But Amcor PET Packaging was even more surprised at his reaction.

“I loved the way they looked. I had never seen an effect like that before on a PET bottle, so I asked Amcor to duplicate it on a commercial run,” First, who is based in the firm’s headquarters in Cambridge, Mass., said.

Amcor had always viewed the uneven surface as a shortcoming of the proprietary stereo lithography (SLA) process it uses to build prototype molds. Adding layers of liquid resin over each other produces the molds, a process that has the result of making the surface a little grainy; and when the prototype bottles are blow molded, this grainy texture is visible to the eye.

But the bottles produced by these prototype molds otherwise strongly resemble the finished product, and can be easily tested in the customer’s facility. Amcor says this results in a faster time to market and avoids mistakes that could happen with other prototyping processes.

However, because the SLA process produces a purely random texture, developing a production mold was challenging. “We had to go through several iterations to get a pattern out of the production mold that would be acceptable to O Beverages,” Brian Pieszchala, manager of PowerFlex development at Amcor, said.

Amcor sells its rib-less PET bottles under the PowerFlex name, and the 17-ounce bottle it produced for O Beverages is the largest thus far.

This is also O Beverages first time using a hot-fill PET bottle. “We had looked at hot-fill PET bottles when were doing our first launch, but at that time the only ones that were available had ribs,” First explained. “We didn’t like the way the ribs affected the ability to label the bottle, so we went a different direction.”

Amcor PET Packaging (Ann Arbor, Mich.); www.amcor.com; 734-428-9741