Less Expensive and Greener 3-D Printing

An IEEE member recycles milk jugs into printing material

6 May 2013
Photo: Sarah Bird/Michigan Technological University

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Three-D printers seem futuristic. They can “print” versions of equipment for a laboratory, models of a house, and much more. And they do it from the comfort of your office.

Well, the future is here, with more and more 3-D printers popping up in labs. But the machines, which print objects out of plastic filament a layer at a time, are still too expensive to be used as home printers. One IEEE member is working on changing that, by making the process cheaper and at the same time, more environmentally friendly.

Joshua Pearce—a professor of materials science and electrical and computer engineering at Michigan Technological University, in Houghton—has helped develop the RecycleBot, which turns old plastic milk gallons into 3-D printing filament.

“Currently, 3-D filament is sold far above the cost of raw plastic,” says Pearce, who heads the university’s Open Sustainability Technology Group. One spool of the filament costs about US $50. That adds up if you need several spools to print something.

 “Using recycled plastic filament pushes the cost of the materials for 3-D printed objects to literally pennies,” Pearce says.

GREENER AND CHEAPER

Work on RecycleBot started in 2011, when two of Pearce’s engineering students, Christian Baechler and Matthew DeVuono, helped him build the first prototype.

How do you turn plastic bottles into printing filament? “We first remove labels from the bottles and cut the containers into sheets, wash them, and shred them in a crosscut office shredder,” Pearce explains. “Then we dump the shreds into RecycleBot’s hopper, which melts and extrudes them into a long, spaghetti-like strings of plastic that can be fed into a 3-D printer.” The machine uses a windshield-wiper motor to turn a standard wood auger, which carries the plastic from the hopper to a heated zone for extrusion.

OPEN SOURCE LOWERS COST

Rather than keep the cost-saving process to themselves, Pearce and his team posted instructions for building a RecycleBot on Thingiverse.com, an open-source site that has more than 76 000 plans for 3-D printing projects. Open-source printing is another way to drive down 3-D printing costs, Pearce says. Such printing involves printers that use free designs and are less expensive than conventional commercial varieties. The designs can be used to make parts for the machines, thereby lowering their cost.

The open-source RecycleBot 3-D printer. Photo: Michigan Technological University

“A 3-D printer can make about half of its own parts,” Pearce notes. High-end machines can cost tens of thousands of dollars, but simpler open-source units range between $250 and $600. They are less expensive because they’re “built on innovations developed rapidly in a global community rather than a single company,” says Pearce. “Currently, most open-source printers are limited to plastics and materials that can be injected through a syringe, whereas high-end (>$600,000) commercial printers can print in metals such as titanium using laser sintering.” Pearce and his team have gotten plenty of praise for sharing RecycleBot. “We have received great feedback and support from around the world,” Pearce says. “That is the real beauty of the open-source hardware community. Today there are many RecycleBot versions and other open-source filament designs.”

Open-source 3-D printing is not just easier on the wallet. It’s also friendlier on the environment, Pearce says.

“My team has found that in most cases, using open-source technologies results in both lower energy consumption and fewer greenhouse gas emissions,” he says. For example, he adds, a printer with RecycleBot filament uses 89 percent less energy than a version with virgin plastic.

Pearce compares the advances in 3-D printing during the past few years to that of the evolution of innovative and technically superior open-source software. “Open-source 3-D printing is evolving at a fantastic rate,” he says. “As we share our ideas and build on the best work of others, costs of many products are being radically reduced.”

INSPIRED TO SOLVE PROBLEMS

Pearce’s interest in science growing up translated into a double major in chemistry and physics at Penn State University, where he received a bachelor’s degree in 1999 and a Ph.D. in materials engineering in 2004.

With a Ph.D. in hand, Pearce had a clear vision for his future. “I knew I wanted to be a college professor,” he says. “You have the freedom to explore new ideas and make science fiction a reality.”

His first job after college was as a physics professor at Clarion University of Pennsylvania. He went on to join Queen’s University in Kingston, Ont., Canada, as a professor of mechanical and materials engineering. There, he ran the applied sustainability lab and helped start a graduate program in the subject. In 2011 he took his current job at Michigan Technological University. He got involved with 3-D printing in 2009 while helping with a student project.

“I needed a plastic shell for a solar-powered laptop we were building,” Pearce says. “The shell cost more than the solar cells—which is absurd. So in trying to find a cheaper way of making a prototype, I found the RepRap [an open-source 3-D printing project] and have been enamored ever since. It is hard to describe how good it feels to generate a design you have in your mind and hold the warm part in your hand after you pry it off the printer bed.

“I recently gave a presentation during which I asked how many people in the room wanted a 3-D printer, and every hand I could see went up.”

For those hoping to get their hands on one, Pearce has some encouraging words: “Most people will have a 3-D printer in their home in the very near future.”

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