A small footprint twin-screw extruder from Thermo Fisher Scientific Inc. is helping the U.S. Army to reduce its plastic waste and, ultimately, shorten the lead time and lower the cost for replacement parts needed by troops in remote areas.
Waltham, Mass.-based Thermo Fisher sold its Process 11 parallel twin-screw extruder to the Army in 2017 for an undisclosed amount. The machine will be used to produce 3D filament from post-consumer PET, which will then be used to 3D print spare parts as needed.
The strategy stems from a collaboration between the U.S. Army Research Laboratory (ARL) and the U.S. Marine Corps that resulted in the discovery of using recyclable plastics from discarded water bottles, milk jugs and yogurt containers, for example, for 3D printing parts that soldiers may need on the battlefield or in more isolated areas.
The study of the potential applications is being led by ARL researcher Nicole Zander and Capt. Anthony Molnar of the U.S. Marine Corps. So far, research has resulted in the production of a 3D filament made of 100 percent recycled PET from bottles or containers without any chemical modifications or additives.
"The idea is if they have a gear or a sprocket or something that's broken, it's very difficult for them to go out and source that. It's also dangerous for them to source it, so they won't be able to be self-sufficient," Steve Post, business development manager at Thermo Fisher, said in a March 26 phone interview.
"Our role was to come up with a machine that was scalable [and] could process these materials," he added. "With polyester, you're driving off the moisture, so that's why you need something that's fully scalable."
The 11 mm co-rotating twin-screw extruder is a fully scalable unit with a maximum output of 2-5 pounds per hour. It has a 40:1 L/D ratio. As Thermo Fisher's smallest twin-screw extruder — the company offers diameters up to 24 mm — it takes up just under 5 square feet of lab space.
"It has the full functionality of most larger size compounding extruders," he said.
While the Army is not new to additive manufacturing — ARL has been 3D printing parts for about 18 years — its research in determining recycled PET as a viable feedstock is a big step toward improving sustainability by reducing plastics waste.
PET water bottles and packaging are among the most common types of waste found on the battlefield, the Army said.
"Most waste is disposed of in open burn pits, which is not optimal for human health and the environment," Zander said in a March 28 email. "Reuse/reclamation/recycling of these materials will provide a huge benefit to the military."