Can 3D Printing Alone Deliver Finished Parts?

One of the most well-known 3D-printed parts: a fuel nozzle for the CFM LEAP engine. (Image courtesy of General Electric.)

It’s not unreasonable to expect that 3D printers will become a staple on factory and job shop floors in the near future. But will they ever replace factories and job shops entirely?

Ten or twenty years ago, many engineers would have answered enthusiastically in the affirmative. Nowadays, this possibility seems much less likely.

To be sure, additive manufacturing is still an exciting prospect for many engineers—especially the latest generation. However, several factors have conspired to restrain the once unbridled enthusiasm surrounding this technology, including cost, speed and quality of 3D-printed parts.

These barriers could be overcome as additive manufacturing technology improves. However, even if this becomes the case, efficiency might still dictate that the best way to use 3D printing is as a starting point.

The three examples below illustrate the advantages of treating near net shapes, rather than finished parts, as the goal of additive manufacturing.

Additive Manufacturing + Grinding

Last year, ELB-Schliff introduced the millGrind hybrid grinding machine in a joint project with Hybrid Manufacturing Technologies. This machine features laser cladding for additive manufacturing in addition to grinding, milling and boring. The millGrind was designed for the turbine industry, so in addition to machining new blades and vanes, it can also be used to rebuild worn areas of a part.

You can see it in action here:

“This millGrind machine offers a new level of flexibility by reducing the number of setups needed to get finished parts,” said Markus Stanik, the managing director for the millGrind project. “We believe that our customers will benefit from both the ability to add metal and mill features together with precision grinding surfaces and profiles.”

Given that additively manufactured parts tend to have rougher surface finishes compared with other operations, combining additive manufacturing and grinding in a single machine makes perfect sense. Even if we can improve the surface finish of 3D-printed parts, doing so requires printing at higher-resolutions, which means printing slower.

Additive Manufacturing + Milling

DMG MORI's LASERTEC 65 3D combines 5-axis milling with additive manufacturing via a laser metal deposition process. The idea here is to reduce the time it takes to machine parts with complex geometries by switching back and forth between laser and cutting tools.

Check it out:

The introduction of additive technology makes machining large workpieces with high stock removal volumes much more economical. However, as with other additively manufactured parts, the subtractive process is still essential for finishing the part.

The company emphasizes the fact that the additive process used by the LASERTEC is up to 10 times faster than generation via powder bed, but that’s still slow compared to the machine’s milling speed. The company could work toward improving the speed of the additive process even further, but why bother if it’s faster to create a near net shape and then mill it to spec?

Additive Manufacturing + Hot Isostatic Pressing

Sintavia’s recently opened additive manufacturing center will soon be adding a hot isostatic press (HIP) to its production line, with the aim of manufacturing metal parts that meet the standards of the aerospace and defense industries.

The QIH 15L hot isostatic press. (Image courtesy of Quintus.)

“Without HIP technology, additively manufactured parts are susceptible to porosity and lack of fusion. HIP allows for near 100 percent net-density parts,” said Sintavia founder Brian Neff.

Manufactured by Quintus Technologies, the press incorporates proprietary technology that combines densification and heat treatment in a single machine. The press features a hot zone capability of 7.3 x 19.7 inches (186 x 500mm), enables pressures up to 30,000 psi (207 MPa), and handles temperatures up to 2550°F (1400C).

“As the additive manufacturing process continues to penetrate various supply chains, not just aerospace and defense, you’ll see more applications requiring HIP-ing,” Neff added. “For certain very critical parts, HIP will become more or less the standard.”

Although metal additive manufacturing is continuing to improve in terms of both fusion and porosity, it could very well reach a point where it’s not worth investing further resources for these improvements—at least, not when HIP can do the job faster and at a lower cost.

Additive Manufacturing and the Factories of the Future

One version of the future of manufacturing involves radical decentralization—monolithic factories in strategic geographic locations are replaced by smaller, local 3D printing centers. Based on a recent announcement, UPS seems to be betting on that version.

Additive manufacturing systems integrated on the shop floor in Stratasys' Factory of the Future vision. (Image courtesy of Stratasys.)

One the other hand, the future of manufacturing could involve centralization of a different kind. Imagine industrial 3D printers at the start of the production line, creating near net shapes that are then transferred to other machines for finishing.

It’s impossible to say for certain which model is more likely. However, consider two competing companies, each trying to set up their manufacturing operations based on one these two scenarios. Which do you think would win in the long run?

Place your bets in the Comments below.