Mechanical, Thermal Factors Are Key Bottlenecks to 3D Printing, Researchers Say

Researchers have identified the key bottlenecks to 3D printing that if remedied, could speed up the entire process.

As 3D printing matures, researchers are looking for new ways to work with new materials and generally improve additive manufacturing (AM) machines and processes to make this method of fabrication faster and more efficient.

As part of these efforts, a team of researchers from Binghamton University, State University of New York, and MIT worked together to identify key bottlenecks in 3D printers finding that improvements to mechanical and thermal factors could speed up the entire process.

Led by Professor John Hart from the Department of Mechanical Engineering and Laboratory for Manufacturing and Productivity at MIT, and including Binghamton Assistant Professor of Mechanical Engineering Scott Schiffres, the team examined the most common extrusion-based polymer additive
manufacturing processes in both desktop and professional machines.

From their observations, they found that the primary bottlenecks are a combination of mechanical and thermal elements, Schiffres told Design News.


3D printing bottlenecks

A researcher at Binghamton University explores how to eliminate current bottlenecks to 3D printing to speed up the process. Researchers there teamed with others at MIT and State University of New York to identify ways to improve 3D printing. (Source: Binghamton University)


Many conventional desktop and professional AM systems build objects at about 10-20 cubic centimeters per hour when printing at a 0.2 millimeter thickness. Researchers found that one limitation of the system lies in the pinch-wheel mechanism used to feed building material, Schiffres said. That wheel is limited in the force it can use, which is about 60 newtons, and the feed rate--about nine millimeters per second--to fully melt building material.

“Mechanically, the machines can only push so hard on the filament before the wheels that feed the filament start to slip, like a car skidding,” Schiffres explained. “To effectively use this filament feed force, you need to
heat the filament, as the polymer flows much easier at higher temperatures. On the other hand, as you print faster, the filament has less residence time to warm up.”

The team also analyzed the print resolution possible with current AM systems, and found limitations there as well, he said. “To print finer features, you have to squeeze the plastic out of a smaller nozzle, which is slower due to the polymer having to be squeezed through a smaller opening,” Schiffres said. “Another complication is actually the control of the print head.”

Understanding of these rate limits will allow researchers and companies to
design improved machines that can print faster, as well as be custom built  o achieve the best combinations of resolution and throughput, he said.

Researchers published a paper on their findings in the journal Additive Manufacturing . The team is currently studying how to heat the polymer used in AM processes more rapidly, as well as how to increase the force capacity of the extrusion mechanism to remedy the bottlenecks they’ve identified, Schiffres said.

In the next phase of their work, researchers will focus on the individual modules--like the heater and filament feed assembly--to identify improvements, he said. “Another factor to consider is that the mass of the extruder printhead impacts the acceleration and accuracy of the

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