The right screw design means green results and better production

Atlanta — The plastics materials sector is responding to today's stronger-than-ever "green" momentum by developing bioplastics and beefing up recycled content, both mechanical and chemical. And researchers are trying exotic new plant-based fillers like corn husks, rice hulls and hemp.

But all those new materials need laboratory testing and validation. Typically, companies trying out new materials go to suppliers of compounding machinery or extruders.

But the screw manufacturers seem like an underutilized resource. That's where Glycon Corp. comes into play — and becomes the topic for this month's Best Practices.

We travel to small-town Tecumseh, Mich. … well, Tecumseh via Atlanta, where Glycon founder Jeff Kuhman explained the Bio-Screw program, at the Society of Plastics Engineers' Annual Blow Molding Conference.

Interviewed at Glycon's booth, Kuhman also said the plastics industry needs greater efforts to teach young people about plastics and get them interested in manufacturing.

"That's what we really need. We go into these industry meetings, as adults, and we say, 'Well are we gonna be able to change people's minds fast enough to save our industry?' But educating young people is the real key thing to do."

Kuhman formed Glycon, originally named Great Lakes Feedscrews, in 1978. He has become very interested in how the plastics industry can evolve to support a circular economy and what role Glycon can play.

That's why Glycon has rolled out Bio-Screw to highlight its commitment to helping the industry create bio-based plastics. The company makes screws for single-screw plastics machinery, like injection molding, extrusion and blow molding. That gives Glycon an advantage: the ability to modify and recut its screws to get optimum output performance.

Glycon has about 25 different screw configurations in its laboratory, which is run by Trevor Stornant, technical support engineer.

"So what we can do on-site is, when the customer brings in their polymer that they're looking to optimize a screw design on, we can put a design in that we feel is the best candidate, and we can modify it on-site, in our factory, put it back in the machine and just keep adjusting the screw," Stornant said.

The lab is right next to the factory in Tecumseh.

Kuhman said Glycon has worked closely with major companies on sustainable materials, starting with Phoenix Technologies International LLC, a pioneering recycler of post-consumer PET in Bowling Green, Ohio, founded in 1992.

"We've done their screws since the first day that they were in business, for reprocessing of PET," he said. "All those screws are our designs. That's where we cut our teeth really, was to work with them. Because there was an awful lot of contaminants in the material that they got."

Glycon also worked with Braskem SA, NatureWorks LLC's Ingeo PLA resin, Novamont SpA, Envision Plastics and Algix LLC to present a circular economy theme displayed at NPE2018.

Kuhman said Glycon is eager for more such work through Bio-Screw. One key feature of the screw maker's screw design lab — now called the Innovation Lab — is the use of Dynisco's ViscoIndicator, which duplicates the test conditions of a meltflow rate tester, or capillary rheometer, right on an extruder. The ViscoIndicator takes a side stream from the extruder that goes through a metering gear pump, measuring things like feeding, flow rate, shear stress and viscosity.

Kuhman said that information is valuable.

"We get lots of valuable readings that we utilize in the design of the screw. We get the information we need off the Dynisco machine," he said. "Because we expect to see a lot of different materials, we're going to get a lot of regrind, we're going to get a lot of composites, we're going to get bioplastics."

Kuhman explained how Glycon's Bio-Screw effort can help companies trial, test and develop new materials: "The crux of the issue is that you're developing a material that is going to contribute to a full-circle economy. And it's going to change its processing characteristics."

"And if you're running 500 pounds an hour in your machine now — and you have this biofavorable material that you're buying from NatureWorks or one of the other people we've done testing for, is getting 300 pounds. And you run the new material, that's good for the environment, but you're saying, wait a minute, I really want to contribute to the environment but if I keep running 300 pounds an hour, I'm gonna go out of business. I need 500."

Kuhman said Glycon is in a good position to design a custom-screw for these applications.

"Let us run the material and process it. Let us design the screw so that you can get the melt properties you need and also the output you need," he said.

Material companies can send in samples for trials. Or processors can come to Tecumseh and work directly with Glycon, said Stornant, the head of the lab.

"We'll have customers in for runoffs and they can help us dial-in what they're looking for in their process," Stornant said.

Kuhman said Glycon is making a long-term effort at sustainable practices — right from its front yard, where a green flag flies right under the United States flag. After the first of the year, he will become chairman and chief sustainability officer. His son, Jon Kuhman, is moving from vice president of engineering to president.

Jeff Kuhman lives a few miles from Glycon, so he will certainly be around. But the company founder said he's looking forward to working on the issues of a green future for plastics and spreading the word among young people. He drives a Chevy Volt, recharged at night by solar shingles on the roof of his house.

He pointed out that Glycon sends all of its steel chips from machining to get recycled. Kuhman also will be promoting the company's EMT — for electronic measurement and tracking — patented this year. EMT enables processors to electronically measure screw and barrel wear, right on the machine, without the need to take the equipment apart and pull the barrel. Software automatically calculates the rate of wear and creates an historical record, so processors can schedule component replacements.

Kuhman said EMT also has a green aspect, since plant technicians typically crank up the power to compensate for screw and barrel wear.

Glycon also supports bag and bottle collection for recycling, both internally at the shop and out in the community.

But educating young people is No. 1 on the list of sustainability initiatives for Glycon. Officials got one idea at the company's Christmas party in 2017. While family members were getting a tour of the factory, Stornant kept the children occupied in the lab. They brought in plastic bottles from home.

"Then we lined the kids up. The kids would put their own bottle they brought in, into the grinder. We ground up the bottles. And then after everyone had put their bottles in, Trevor takes the hopper out of the grinder, dumps it into the hopper on the machine in our extruder in the lab … and runs it through. We have a sheet line, so we have it set up where it cuts off about a 10-inch sample of it. They take their regrind, then you hand them a sheet of plastic and write their name on it."

Twice a year, Glycon also hosts local junior high school students, doing the same demonstration.

"With them we like to talk about the use of plastic, good things about plastic. Not too long, because you don't want to lecture them," he said.

Simple and direct. Show hands-on recycling. Trial run "green" materials, then run over to the shop and machine adjustments on the screw.

Those are Best Practices by a company that makes screws — a key component used to melt and convey plastic on nearly every type plastic processing machine.