Nov 29, 2017 | By Benedict

Engineers at MIT have developed a laser-assisted FDM 3D printer that prints around 10 times faster than average desktop machines. The new 3D printer’s unusual printhead uses a laser and novel screw mechanism to increase flow rate.

MIT researchers Jamison Go and Anastasios John Hart have developed a novel 3D printer printhead 

Lasers are a common component in many 3D printers. Stereolithography (SLA), selective laser melting (SLM), and selective laser sintering (SLS) all have a laser at their core that is used to turn their respective base materials into 3D printed objects.

But the most common type of desktop 3D printer, the fused deposition modeling (FDM) printer, doesn’t usually come with a laser, instead using a heater cartridge in its printhead “hot end” to melt plastic.

But could a laser improve your average FDM 3D printer? MIT researchers Jamison Go and Anastasios John Hart have just developed a desktop 3D printer that is reportedly 10 times faster than most commercial counterparts. And the secret to this speed, the researchers say, is a laser-assisted, screw mechanism printhead.

These two new mechanisms are not common features of FDM printheads, yet both serve to increase material flow rate. The screw mechanism feeds the plastic filament through a nozzle at high force, while the laser rapidly heats and melts the material.

A tenfold speed increase is definitely food for thought, and Hart thinks this new kind of printhead could make FDM 3D printing a more viable production technique—as opposed to a tool for prototyping only.

It’s easy to see why: a one-hour print job could be shortened to five or 10 minutes, which means skilled workers like repair technicians could use such a 3D printer on the job, quickly printing a new spare part after diagnosing a problem.

Even emergency medicine applications could benefit from a simple yet speedy 3D printer like the one developed at MIT.

Selection of objects 3D printed on the new MIT printer

(Image: Chelsea Turner)

But the new 3D printer wasn’t made for any particular end task; rather, its development was an attempt to overcome three problems associated with FDM 3D printing: slow printhead speed, low extrusion force, and slow heat transfer.

“Given our understanding of what limits those three variables, we asked how do we design a new printer ourselves that can improve all three in one system,” Hart says. "And now we've built it, and it works quite well.”

The screw mechanism replaces the standard "pinch-wheel" mechanism of FDM printheads, which can only go so fast without losing grip of the filament.

The new device, which turns within the printhead, is able to process a specially developed textured filament, which increases grip and allows the printhead to feed the filament through at much higher speeds.

The laser, on the other hand, serves to heat and melt the 3D printing filament before it passes through the nozzle. It ensures the filament is more quickly and thoroughly melted than is possible using the conduction heating of standard FDM printheads.

The heat of the laser can be adjusted by quickly turning it on and off.

Another speed-increasing feature of the new 3D printer is its new gantry design. An H-shaped frame is powered by two motors and connected to a motion stage holding the printhead. The system is fast enough to keep up with the increased flow rate of the printhead.

To prove the power of the new 3D printer, the MIT researchers printed several complex parts, each of which took only five to 10 minutes. These included a miniature chair, a simplified model of Building 10 at MIT, eyeglasses frames, a spiral cup, and a helical bevel gear.

Unfortunately, the machine isn’t yet perfect. While attempting to print at such high speeds, the researchers found that the printed layers, being subject to such high force and temperature, sometimes haven’t cooled down and hardened by the time the next layer is applied.

This means the researchers have had to actively cool a part as it prints—a challenge they will continue to address as they refine the printer over time.

The MIT team also plans to try printing with high-strength polymers and composite materials, as well as attempting to tackle large-scale 3D printing.

The research, “Fast Desktop-Scale Extrusion Additive Manufacturing,” has been published in Additive Manufacturing.

 

 

Posted in 3D Printer

 

 

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kr_ wrote at 12/2/2017 3:23:36 PM:

It's quite easy to extrude 10 times faster... The real challenges, as many found out before, are to obtain accurate prints with sharp corners and layer adhesion.

Chris wrote at 11/30/2017 6:35:23 PM:

I wonder if Jim Combs and Stratasys will have anything to say about this. He invented this years ago.

RepRapper wrote at 11/29/2017 6:19:43 PM:

Unfortunately, the machine isn’t yet perfect. While attempting to print at such high speeds, the researchers found that the printed layers, being subject to such high force and temperature, sometimes haven’t cooled down and hardened by the time the next layer is applied. Yes... all the RepRappers have known this for years..

Maave wrote at 11/29/2017 2:59:16 PM:

Thankfully Mr Hart has also posted this research paper on Cornell's ArXiv reposity, so it's not locked behind a journal paywall https://arxiv.org/abs/1709.05918

Banker Overlord wrote at 11/29/2017 2:55:30 PM:

At those kinds of speeds, it's a game changer.



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