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Most Recent News Item:
Technique Invented That Could Transform Additive Manufacturing Processes
August 7, 2020

Additive manufacturing—or 3D printing—uses digital manufacturing processes to fabricate components that are light, strong, and require no special tooling to produce. Over the past decade, the field has experienced staggering growth, at a rate of more than 20% per year, printing pieces that range from aircraft components and car parts to medical and dental implants out of metals and engineering polymers. One of the most widely used manufacturing processes, selective laser sintering (SLS), prints parts out of micron-scale material powders using a laser: the laser heats the particles to the point where they fuse together to form a solid mass.

“Additive manufacturing is key to economic resilience,” say Hod Lipson, James and Sally Scapa Professor of Innovation (Mechanical Engineering) at Columbia University School of Engineering and Applied Science. “All of us care about this technology—it’s going to save us. But there’s a catch.”

The catch is that SLS technologies have been limited to printing with a single material at a time: the entire part has to be made of just that one powder. “Now, let me ask you,” Prof. Lipson continues, “how many products are made of just one material? The limitations of printing in only one material has been haunting the industry and blocking its expansion, preventing it from reaching its full potential.”

According to information, wondering how to solve this challenge, Prof. Lipson and his PhD student John Whitehead used their expertise in robotics to develop a new approach to overcome these SLS limitations. By inverting the laser so that it points upwards, they invented a way to enable SLS to use—at the same time—multiple materials. Their working prototype, along with a print sample that contained two different materials in the same layer, was recently published online by Additive Manufacturing.

Selective laser sintering traditionally has involved fusing together material particles using a laser pointing downward into a heated print bed. A solid object is built from the bottom up, with the printer placing down a uniform layer of powder and using the laser to selectively fuse some material in the layer. The printer then deposits a second layer of powder onto the first layer, the laser fuses new material to the material in the previous layer, and the process is repeated over and over until the part is completed.

The researchers decided to find a way to eliminate the need for a powder bed entirely. They set up multiple transparent glass plates, each coated with a thin layer of a different plastic powder. They lowered a print platform onto the upper surface of one of the powders, and directed a laser beam up from below the plate and through the plate’s bottom. This process selectively sinters some powder onto the print platform in a pre-programmed pattern according to a virtual blueprint. The platform is then raised with the fused material, and moved to another plate, coated with a different powder, where the process is repeated. This allows multiple materials to either be incorporated into a single layer, or stacked. Meanwhile, the old, used-up plate is replenished.

In the paper, “Inverted multi-material laser sintering,” the team demonstrated their working prototype by generating a 50 layer thick, 2.18mm sample out of thermoplastic polyurethane (TPU) powder with an average layer height of 43.6 microns and a multi-material nylon and TPU print with an average layer height of 71 microns. These parts demonstrated both the feasibility of the process and the capability to make stronger, denser materials by pressing the plate hard against the hanging part while sintering.

“This technology has the potential to print embedded circuits, electromechanical components, and even robot components. It could make machine parts with graded alloys, whose material composition changes gradually from end to end, such as a turbine blade with one material used for the core and different material used for the surface coatings,” Prof. Lipson notes. “We think this will expand laser sintering towards a wider variety of industries by enabling the fabrication of complex multi-material parts without assembly. In other words, this could be key to moving the additive manufacturing industry from printing only passive uniform parts, towards printing active integrated systems.”

The researchers are now experimenting with metallic powders and resins in order to directly generate parts with a wider range of mechanical, electrical, and chemical properties than is possible with conventional SLS systems today.

News Items
Below are listed the 12 most recent News Items.
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Technique Invented That Could Transform Additive Manufacturing Processes
August 7, 2020

One of the most widely used manufacturing processes, selective laser sintering (SLS), prints parts out of micron-scale material powders using a laser…

Researchers 3D Print Functioning Human Heart Pump
August 7, 2020

Researchers have 3D printed a functioning centimeter-scale human heart pump in the lab.

Interactions Between Bees and Soils Studied
August 6, 2020

Researchers are studying the interaction between the bees and soil in agricultural settings.

3D-Sensing Wristband Developed
August 6, 2020

Researchers have developed a wrist-mounted device that accurately tracks finger and hand movements using four tiny cameras.

D4i Webinar Scheduled
August 5, 2020

D4i brings a long-awaited standardization for luminaires.

Mussels Shown To Form Weaker Attachments In Iron-deficient Seawater
August 5, 2020

As oceans become more acidic in a changing climate, iron dissolves and is less bioavailable to filter feeders…

New Publication Provides Overview Of Design Connections For Composite Special Moment Frames
August 4, 2020

The American Society of Civil Engineers’ (ASCE) new publication, Composite Special Moment Frames: Wide Flange Beam to Concrete-Filled Steel Column Connections provides…

Health Markers In Thread-Based, Wearable Sweat Sensors Detected
August 4, 2020

Engineers have created a first-of-its-kind flexible electronic sensing patch that can be sewn into clothing to analyze your sweat for multiple markers.

NFPA Announces Live Virtual Training Courses
August 3, 2020

Courses incorporate dynamic interactive online components with real-world setting scenarios.

Drawing Electronics On Skin Studied
August 3, 2020

One day, people could monitor their own health conditions by simply picking up a pencil and drawing a bioelectronic device on their skin.

AHRI Issues Call For Comments On Standards Revisions
July 31, 2020

Public and stakeholder review and comment sought for the purpose of developing consensus standards.

ASHRAE Issues Call For Comment - Addenda to Standard 90.1-2019
July 31, 2020

Public and stakeholder review and comment sought for the purpose of developing consensus standards.

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