3D printing is starting to evolve from a prototyping technology into a production technology. It's what’s called a bridge-manufacturing technique, a means of making moderate quantities of parts to go into real working products. Bridge manufacturing lets OEMs bring designs to market faster and modify features to customer demands before finalizing tooling to make the best part iterations in bulk.

Sometimes called pilot or rapid manufacturing, the technique potentially lets OEMs get new versions of products into production without tool changes for every design modification.

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Metal’s Been There, Done That

Some OEMs, particularly those that make sophisticated metal parts for medical designs, have already evolved 3D printing beyond prototyping and bridge manufacturing into a full-scale production practice. Consider Arcam AB in Sweden, which builds electron-beam melting (EBM) printers and supplies cobalt chrome and titanium for the machines to process. Its largest customers are orthopedic-device companies that 3D-print dental, shoulder, and hip replacements in batches of thousands or more.

In fact, the 3D printing of final-run parts has grown exponentially over the last decade, according to Wohlers Associates Inc., Fort Collins, Colo. Last year, 28.3% of the $2.2 billion spent on 3D printing went to making end-use parts, up from 4% only a decade ago. Analysts expect that trend to continue unabated.

Likewise, tooling OEMs increasingly make mold inserts for injection-molding plastic parts with direct metal laser sintering (DMLS) machines from EOS GmbH in Germany. (See July 2014 Machine Design, How To Design 3D-Printed Metal Tooling.) Space Exploration Technologies Corp. (SpaceX), Hawthorne, Calif., also uses DMLS and regenerative cooling to 3D-print engine chambers in Inconel, a superalloy with high strength and toughness. The chambers go in thruster engines that fit into the sidewalls of the Dragon manned spacecraft. A set of eight engines produces up to 120,000 lb of axial thrust and lets astronauts land the craft (via propulsion control) if there’s an emergency during launch.

In the same way, GE Aviation, Lafayette, Ind., now prints fuel nozzles for LEAP jet engines at its Cincinnati facility, with direct metal laser melting (DMLM) directly from CAD files. The parts maintain the same material properties and density as traditionally manufactured pieces, but with far more complex geometries. So, they’re 25% lighter and five times stronger than previous nozzles.

Plastics Catch Up

Advances in additive-manufacturing machines and materials to print plastic-composite parts are spurring new uses of bridge manufacturing. It’s a boon to consumer-product and synthetic-component makers, because the forming of plastic parts by traditional injection molding is notoriously expensive and slow.

“The early adopter was the electronics industry,” says Jeff Hanson, director of business development at the contract printer RedEye by Stratasys Inc., Eden Prairie, Minn. “Even now, these companies use additive manufacturing as a bridge to traditional manufacturing processes because many of their end-use parts are made of the same thermoplastics used in fused-deposition modeling (FDM).” Second only to selective-laser sintering (SLS), FDM, under the generic category of fused-filament fabrication or thermoplastic extrusion, lets OEMs launch parts in low volumes.

Also leveraging bridge manufacturing is the medical-device industry, mostly to make device skins for clinical trials and limited market releases. According to Hanson, such manufacturers favor FDM and PolyJet prints of biocompatible materials because they can bring low product volumes to the highly regulated medical market.

Consumer products could be next. Olloclip LLC, Huntington Beach, Calif., which makes souped-up camera lenses for cellphones, has 3D printing in its plans. “When we finalize a new design, it takes six to eight weeks to produce the tooling for the injection molds,” says founder Patrick O’Neill. “It would be nice to use 3D printing to deliver products in that in-between time, so we can get to market faster.” The company is considering an Objet 500 Connex3 printer from Stratasys, because that machine could print clear lenses and colored bodies all in one shot.

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