Product Design Engineering

Mainstreaming alert: 3D-printed parts in GE engines and X-ray machines

When General Electric puts metal 3D-printed parts in its jet engines and X-ray machines, you know the manufacturing technology has gone mainstream.

That's what research summarized in this year's Wohler’s Report on 3D printing also suggests. It bears out what we’re seeing in several industries: Metal additive manufacturing — or at least the sale of machines that produce metal parts through additive means — grew 76% over the last year, with several hundred now sold annually.

Note that these aren’t desktop printers, but large industrial machines that GE, Airbus, and other large companies use to make high-performance and complex metal parts for aerospace and medical products — at least according to Terry Wohlers, founder and president of Wohlers Associates.

To be sure, many argue that the long history of additive manufacturing — for metal parts, at least — belies the current hype about the technique's exciting newness.

But GE, Fairfield, Conn., now actively scouts for ways to leverage 3D printing. Case in point: GE and NineSigma — a company that organizes open innovation from outside companies through social media and more — established the 3D Printing Production Quest last year to challenge participants to use additive manufacturing to produce precision parts made of refractory metals.

In April, GE announced the contest’s three winners:

• Martin Leuterer, EOS GmbH, Germany

• Rob Snoeijs, LayerWise, Belgium

• Bernhard Tabernig, PLANSEE SE Innovation Services, Austria

Each got $50,000 for devising ways to make parts with additive manufacturing from super-dense Niobium and Molybdenum — a capability that could transform how components are manufactured for X-ray-based medical imaging for mammography, cardiac catheterization, and computed tomography. That's because Niobium and Molybdenum are refractory metals used in X-ray machines and X-ray-channel tubes, because they block X rays like lead, but without the health and environmental hazards.

More specifically, in medical X-ray machines, parts made of refractory metals, including X-ray source tubes, control the path of X rays from the source through the patient's body. The location of the tube in question is illustrated at 2:44 in this video:

The main benefits of refractory metals — their high melting temperature (up to 3,400° C) and ability to absorb energy — are also what make it challenging to print refractory-metal parts.

Judges for the 3D Printing Production Quest picked the winners by statistically analyzing the precision of the 3D printed parts each team made, plus other measurable part qualities.

The machine by winner Bernhard Tabernig, from the company Plansee, makes refractory-metal parts with a honeycomb structure.

But according to Tabernig, his company's 3D-printing machine doesn’t use conventional selective laser sintering (SLS) of metal powder, currently the most common mode of 3D printing metal parts. Instead, the machine makes parts by a new version of the process called selective laser melting (SLM). As explained in this article from 2010, SLM resembles selective laser sintering (SLS) except that it fully melts the metal powder, while in SLS, the metal just comes close to the melting point.

With SLM, thin layers of powder are laid on a base plate. A laser fuses the powder wherever the driving CAD file indicates a part feature. Once the job is done, any leftover powder not melted inbto the part can be used for making another part.

Besides the zero-waste nature of SLM, it has the same benefits of other 3D printing machines: It makes myriad parts without needing special tools or dedicated molds.

As GE has already found, the SLM process is particularly useful for making parts for medical technology. That’s because SLM lets manufacturers make parts for X-ray diagnostics machines with complex honeycomb-like grid structure to maximize the absorption of the scattering radiation, according to Plansee project engineer Peter Singer.

By 2019, the global medical-imaging market will reach $35.35 billion ... and GE sees additive manufacturing as a way to make new designs that reduce cost and improve image quality and diagnostic capabilities.

So much for the dismissal of additive manufacturing as a "cute" maker-level mode of production.


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