Electron-Beam Freeform Fabrication

NASA Langley Research Center (LaRC) is the originator and world leader in Electron Beam Freeform Fabrication (EBF3) technology development. The Additive Manufacturing Process was primarily developed and engineered by Karen Taminger, material research engineer for NASA LaRC. (EBF3) is a NASA-patented additive manufacturing process designed to build complex, near-net-shape parts requiring substantially less raw material and finish machining than traditional manufacturing methods. There is a history of over a decade of successful collaboration with other NASA centers (JSC, GRC, GSFC and MSFC), Federal agencies and the U. S. aerospace industry. (EBF3) is a process by whichNASA plans to build metal parts in zero gravity environments; this layer-additive process uses an electron beam, and a solid wire feedstock to fabricate metallic structures. The process efficiencies of the electron beam and the feedstock make the EBF3 process attractive for in-space use.

The operational concept of (EBF3) is to build a near-net-shape metal part directly from a Computer Aided Design (CAD) file without the need for molds or tooling dies. Current computer-aided machining practices start with a CAD model and use a post-processor to write the machining instructions (G-code) defining the cutting tool paths needed to make the part. (EBF3) uses a similar process, starting with a CAD model, numerically slicing it into layers, then using a post-processor to write the G-code defining the deposition path and process parameters for the (EBF3) equipment. (EBF3) uses a focused electron beam in a vacuum environment to create a molten pool on a metallic substrate. The beam is translated with respect to the surface of the substrate while metal wire is fed into the molten pool. The deposit solidifies immediately after the electron beam has passed, having sufficient structural strength to support itself. The sequence is repeated in a layer-additive manner to produce a near-net-shape part needing only finish machining. The (EBF3) process is scalable for components from fractions of an inch to tens of feet in size, limited mainly by the size of the vacuum chamber and amount of wire feedstock available.

In reality, EBF3 works in a vacuum chamber, where an electron beam is focused on a constantly feeding source of metal, which is melted and then applied as called for by a drawing—one layer at a time—on top of a rotating surface until the part is complete.

Commercial applications for EBF3 are already known and its potential already tested, NASA reported, noting it’s possible that, within a few years, some aircraft will be flying with large structural parts made by this process.

To make EBF3 work there are two key requirements: A detailed three-dimensional drawing of the object to be created must be available, and the material the object is to be made from must be compatible for use with an electron beam.

First, the drawing is needed to break up the object into layers, with each cross-section used to guide the electron beam and source of metal in reproducing the object, building it up layer by layer.

Second, the material must be compatible with the electron beam so that it can be heated by the stream of energy and briefly turned into liquid form, making aluminum an ideal material to be used, along with other metals.

In fact, the EBF3 can handle two different sources of metal—also called feed stock—at the same time, either by mixing them together into a unique alloy or embedding one material inside another.


Electron-Beam Freeform Fabrication Video


3D Printing Technology - Electron Beam Freeform Fabrication (EBF3)

3D Printing Technology – Electron Beam Freeform Fabrication (EBF3)



Abbreviation: EBF3
Material type: Wire
Materials: Almost any metal alloy
Max part size: N/A
Min feature size: N/A
Min layer thickness: N/A
Tolerance: N/A
Deposition rates: 330 to 2500 cm3/hr (20 to 150 in3/hr)
Build speed: Average
Applications: Aerospace structural applications, hot structures, launch vehicles


Source: NASA and Wikipedia

One comment

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