An Insider's View on 3D Printing in Aerospace

September 11, 2015 | Author: Donald Godfrey

In January 2015, Honeywell became the first company to use electron beam melting (EBM) ― popularly known as 3-D printing―to produce an aerospace component from the nickel-base superalloy Inconel 718. 

Electron beam melting technology uses an electron beam instead of a laser that is found in more conventional metal sintering / fusion processes often times referred to as direct metal laser sintering (DMLS).

The differences between the two technologies (at a high level) are as follows:

1)The EBM build process always occurs above 1,900 °F for the Inconel material.  The high temperatures reduce residual stresses in the final parts, whereas laser processes operate in an environment of around 250°F that produces residual stresses, due to the rapid solidification of the material.

2)The EBM process uses a 3000 watt electron gun to build and preheat the build chamber.

3)The EBM process has MultiBeam technology that allows several melt pools to be maintained simultaneously and increase the build speed.

4)The EB process operates in a vacuum (<1X10-4 mbar) and helps eliminate impurities and the laser process operates in a gas shielded environment.

5)After the part is built in a laser process it can be removed from the build chamber.  After the EB part is built, it must be allowed to cool for 8 hours before it can be removed from the machine.

6)After the laser part is built, it is usually placed in a furnace and stress relieved. The cool down period of the EB process serves as the stress relive process .

Through collaborative research efforts with the Oak Ridge National Laboratory, Arcam Corporation announced in June 2014 that Inconel 718 was a supported material for the Electron Beam Machine technology.  Associated technical data was officially released in mid October.

On January 28, Honeywell officially used this material and this technology to make the first Aerospace component which was an experimental design of an existing tube used on its HTF7000 engine.

This process holds the promise of reducing manufacturing costs by 50 percent and dramatically reducing production / delivery time.

The cost savings is generated by combining eight different part numbers into a design defined with one part number. Delivery can be reduced from months to weeks. Overall, the results are a better quality part, improved rolled-throughput yield, less inventory, faster production and lower cost to produce.

Honeywell has several years' experience building components with additive manufacturing technology and superalloy materials, placing those components both in test rigs and flight test beds in preparation to transitioning the technology into production. 

With this successful effort, Honeywell then began producing a rear bearing turbine support (RBTS) with this same technology and material.

The term 'superalloy' refers to an alloy that exhibits several key characteristics including ability to withstand high temperatures. Inconel alloys are oxidation- and corrosion-resistant materials well-suited for service in extreme environments subjected to pressure and heat such as aircraft engines.

Honeywell has identified multiple parts to take into production with 3D printing technology. Those parts will be explained in future blog postings.

Donald Godfrey

Donald Godfrey

Donald Godfrey is an engineering fellow at Honeywell Aerospace.

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