Cypet's new blow molding technology makes world record PET drums
Atlanta — A company from Cyprus, Cypet Technologies Ltd., has developed a new technology for one-step injection stretch blow molding — and at K 2019, it produced a giant 120-liter PET drum at the show.
Single-stage blow molding machines injection mold PET preforms and blow mold them on a single machine. A conventional single stage uses a vertical clamp to injection mold preforms, then a horizontal clamp for blowing bottles.
Cypet's technology works in the opposite way. Constantinos Sideris, managing director of Cypet, described how his company's machine works in a presentation Sept. 17 at the SPE Annual Blow Molding Conference in Atlanta.
"In our technology, we mold the preforms horizontally so that the opening direction of the mold is horizontal. And we blow the bottles vertically so that again, the mold opening is horizontal," he said. "This means that we can put the blow mold and injection mold on one and the same clamping unit, and we open and close both molds together. This is a substantial difference in the mechanics."
Sideris said the Cypet technology is patented in major countries — those that represent 80 percent of global GDP.
The Cyprus-built machine uses an injection molding frame, and it looks like an injection press with two types of processes. A special station transfers the preform to the blow molding area above, does the stretch blow molding and removes the bottles from the blow mold.
"The stretch blowing happens in parallel with the injection molding of the next set of preforms," Sideris said. "The injection mold has a design of a typical two-stage preform mold." Servo-hydraulic power drives all injection movements.
As is typical in single-step blow molding, the preforms do not have to reheat before blowing, which saves energy. Sideris said the Cypet machine also recovers about two-thirds of the blowing area, for reuse in compressed air.
Cyprus is a small island country in the eastern Mediterranean Sea. "Our country is better known by European tourists for its warm weather and beautiful beaches. But we are aspiring to put Cyprus on the world plastic map," Sideris said with a chuckle.
The family business, M. Sideris & Son, was founded in Cyprus in 1968 as a supplier of equipment for the plastics industry. In 2004, the company conceived and applied for patents on a new blow molding process. After building up the company's manufacturing infrastructure, the company commercialized the one-step blow molder in 2013.
Sideris holds a bachelor's degree in chemical engineering from the University of Cambridge and an MBA from Carnegie Mellon University.
Cypet designs the special containers and packages, working with customers. The result is some very large PET containers.
"We supply PET processing systems, which means machine, molds and processing parameters," Sideris said. Everything is tested before delivery. "We are responsible for delivering a system that will produce the PET container that was agreed. So, it's our responsibility to design the preform, manufacture the molds and the machine, test and deliver a system that works," he said.
Sideris said that today, a PET container considered to be 'large' is the size between 10-13 liters.
At the Atlanta blow molding conference, Sideris submitted for the parts competition a 16.5-liter PET bottle in a box for edible oil. The package has a side neck for easy pouring. The box allows for good shipping logistics.
But that's just the beginning, Sideris said. What he called the world's first commercial 50-liter PET application was a beer keg produced in Australia on a Cypet machine. "And the world's second 50-liter-size PET application is now in production in Kenya for milk jugs," he said.
Some of the containers have integrated handles.
"Our vision is value through innovation," Sideris said. "And after this new technology was patented, we continued to innovate with two new patents issued. One patent relates to PET preform production with a different method of post-cooling, and the other one relates to a PET bottle design with an integrated PET handle. Two patents are pending: one concerning the PET beer keg and one concerning a pressure relief valve for making beer kegs very safe."
Sideris said Cypet broke that 50-liter mark by injection stretch blow molding a clear, 60-liter PET container for fruits and vegetables for a customer in Mexico. "It is to replace an injection molded polypropylene. He wanted stackability for see-through crates," he said. "We took up the challenge for this."
But what Cypet calls the world record — on display at K 2019 — was a 120-liter PET behemoth designed as a see-through alternative to the high density polyethylene drum. The first machine to make the 120-liter drum has been sold to a Dutch customer for containing fish oil, according to Sideris.
"Transparency is one difference [between PET and HDPE drums]. Significantly lower weight is another," he said. The smooth and glossy surface is easy to clean.
But Sideris said Cypet does not plan to stop there.
"120 liters is the limit we have reached. And we are very confident that we'll extend that capability and sizes for PET to the very popular size of drums of 220 liters. But that's in the future!" he said.
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