Spray Tips: Fluidized Bed Powder Feeders

October 10, 2017
Source:

In fluidized-bed powder feeders, a bed of powder is continuously agitated by a fluidizing gas, in this case the carrier gas. The intent by design is to suspend a controlled volume of powder in a bed using a controlled volume of gas such that a sample of powder can be drawn off at a uniform rate. To accomplish this, the bed must be in continuous motion—that is, fluidized—and the volumes of gas and powder being removed must be continuously replaced.

Vibrators and/or gravity feed are used to assist and maintain flow from the hopper into the bed. The diagram shows  how the powder-laden carrier gas is aspirated through openings in the carrier-gas tube, using the venturi effect created by gas flowing through the tube.

Volume 5A, Thermal Spray Technology â‡’ Thermal Spray Processes and Coatings â‡’ Process Control and Control Equipment â‡’ Material Feed

NASA rocket engine igniter made of Inconel and copper by hybrid 3D laser printing

October 6, 2017
Source:

NASA Marshall Space Flight Center, Huntsville, Ala., announces that its engineers have tested the first 3D printed rocket engine igniter made of Inconel and a copper alloy. NASA has been making and evaluating durable 3D printed rocket parts made of one metal, but the technique of 3D printing with more than one type of metal is more difficult.

For this prototype igniter, the two metals – a copper alloy and Inconel -- were joined using a unique hybrid 3D printing process called automated blown powder laser deposition. The prototype igniter was made as one single part instead of four distinct components that were formerly brazed and welded together in the past. This bi-metallic part was built during a single process by a hybrid machine made by DMG Mori in Hoffman Estates, Illinois. The new machine integrated 3D printing and computer numerical-control machining capabilities to make the igniter.

While the igniter is a relatively small component at only ten inches tall and seven inches at its widest diameter, this new technology allows a much larger part to be made, and enables the part's interior to be machined during manufacturing—something other machines cannot do. This is similar to building a ship inside a bottle, where the exterior of the part is the "bottle" enclosing a detailed, complex "ship" with invisible details inside. The hybrid process can freely alternate between freeform 3-D printing and machining within the part before the exterior is finished and closed off.

"It is a technological achievement to 3-D print and test rocket components made with two different alloys," saya Preston Jones, director of the Engineering Directorate at Marshall. "This process could reduce future rocket engine costs by up to a third and manufacturing time by half."

Engineers at Marshall, led by senior engineer Robin Osborne of ERC Inc.,  low-pressure hot-fire tested the prototype more than 30 times during July to demonstrate the functionality of the igniter. The prototype, built by a commercial vendor, was then cut up by researchers at the University of Alabama in Huntsville who examined images of the bimetallic interface through a microscope. The results showed the two metals had inter-diffused, a phenomenon that helps create a strong bond.

https://www.nasa.gov/centers/marshall/news/news/releases/2017/nasa-tests-first-3-d-printed-rocket-engine-part-made-with-two-different-alloys.html

America Makes and ANSI collaborate to update standards for additive manufacturing

Source:

America Makes, Youngstown, Ohio, and the American National Standards Institute (ANSI), Washington, have launched Phase 2 of the America Makes & ANSI Additive Manufacturing Standardization Collaborative (AMSC) to update its standardization roadmap for additive manufacturing. The roadmap describes published and in-development standards and specifications for additive manufacturing, and makes consensus-based recommendations to address perceived gaps in standardization.

The AMSC is planning to issue by June 2018 an update to its Standardization Roadmap for Additive Manufacturing, which describes published and in-development standards and specifications for additive manufacturing, and makes consensus-based recommendations to address perceived gaps in standardization. To do so, the AMSC will retain its existing working groups evaluating the need for standards across the lifecycle of an additively manufactured part. These working groups cover horizontal topics that are applicable to all industry sectors in the areas of design, precursor materials, process control, post-processing, finished material properties, qualification and certification, nondestructive evaluation, and maintenance. The updated document will include progress reports on gaps previously described along with any new gaps that are identified.

A significant addition to enhancing the roadmap's value will be the establishment of a new polymers working group, which will endeavor to augment the roadmap's predominant focus on metals by considering standardization needs related to polymers for all horizontal topics across the working groups.

Subject-matter experts interested in participating in one or more of the working groups are invited to review the working group architecture, and return the sign-up sheet. It is envisioned that initially the working groups will hold virtual (online) meetings every two weeks. First meetings will take place in October. Participation in the AMSC is open to additive manufacturing stakeholders that have operations in the United States.

The Phase 2 launch meeting drew 86 attendees with another 56 participating remotely. As the group is working to expand its reach, the agenda included breakout discussions with stakeholders from the following industry-sectors: aerospace/defense, medical, ground vehicle/heavy equipment, energy, and industrial & commercial machinery.

www.ansi.org/amsc