Advanced 3D printer – Courtesy of MIT scientist Luis Fernando Velásquez-García and team
A broken motor can bring an automated machine factory to a halt—and instead of ordering a replacement part that could take days or weeks to arrive, with costly production delays, it may soon be easier, faster, and much cheaper to make a new motor onsite.
MIT researchers announced on Wednesday that they have developed a multi-material 3D-printing platform that could be used to fully print electric machines in a single step, with 3D materials costing just 50 cents.
They used their new system to produce a fully 3D-printed electric linear motor in a matter of hours using five materials. They only needed to perform one post-processing step for the motor to be fully functional.
The assembled device performed as well or better than similar motors that require more complex fabrication methods or additional post-processing steps.
Their system processes multiple functional materials—including electrically conductive materials and magnetic materials—by using four extrusion tools to handle varied forms of printable material, with the printer squeezing them through a nozzle as it fabricates a device one layer at a time.
In the long run, this 3D printing platform could be used to rapidly fabricate customizable electronic components for robots, vehicles, or medical equipment with much less waste.
“This is a great feat, but it is just the beginning. We have an opportunity to fundamentally change the way things are made by making hardware onsite in one step, rather than relying on a global supply chain. With this demonstration, we’ve shown that this is feasible,” said Luis Fernando Velásquez-García, in MIT’s Microsystems Technology Laboratories, and the senior author of a paper describing the 3D-printing platform, published in Virtual and Physical Prototyping.
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To fabricate an electric machine, the researchers needed to be able to switch between multiple materials that offer different functionalities. For instance, the device would need an electrically conductive material to carry electric current and hard magnetic materials to generate magnetic fields for efficient energy conversion.
Most multi-material extrusion 3D printing systems can only switch between two materials that come in the same form, such as filament or pellet, so the researchers had to design their own. They retrofit an existing printer with four extruders that can each handle a different form of feedstock.
They carefully designed each extruder to balance the requirements and limitations of the material. For instance, the electrically conductive material must be able to harden without the use of too much heat or UV light because this can degrade the dielectric material.
At the same time, the best-performing electrically conductive materials come in the form of inks which are extruded using a pressure system. This process has vastly different requirements than standard extruders that use heated nozzles to squirt melted filament or pellets.
“There were significant engineering challenges. We had to figure out how to marry together many different expressions of the same printing method — extrusion — seamlessly into one platform,” Velásquez-García told MIT News.
The researchers utilized strategically-placed sensors and a unique control framework so each tool is picked up and put down consistently by the platform’s robotic arms, and so each nozzle moves precisely and predictably, ensuring that each layer of material lines up properly—because even a slight misalignment can derail the performance of the finished machine.
Making a motor for 50 cents in materials
After perfecting the printing platform, the researchers fabricated a linear motor, like the ones used in applications like pick-and-place robotics, optical systems, and baggage conveyers.
They fabricated the motor in about three hours, with a total material cost of about 50 cents.
Their 3D-printed motor was able to generate several times more movement than a common type of linear engine that relies on complex hydraulic amplifiers. They only had to magnetize the hard magnetic materials after printing to enable full functionality.
“Even though we are excited by this engine and its performance, we are equally inspired because this is just an example of so many other things to come that could dramatically change how electronics are manufactured,” says Velásquez-García.
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In the future, the researchers want to integrate the magnetization step into the multimaterial extrusion process, demonstrate the fabrication of fully 3D-printed rotary electrical motors, and add more tools to the platform to enable monolithic fabrication of more complex electronic devices.
(Original article by Adam Zewe, MIT News)
