Process marries plastics, 3D printing and electroplating

Applications for 3D printing are growing at dizzying speed. One new strategy, however, stands out because it marries plastics, 3D printing and electroplating to easily create a complex research instrument that manipulates individual molecules.

Researcher Andeas Osterwalder used 3D printing to create in plastic the form of a molecular beam splitter, then electroplated it with nickel to give an instrument with the fine detail, mechanical strength and conductivity to perform his experiments.

Osterwalder and colleague Sean Gordon published their work in a recent edition of the peer-reviewed journal​ Physical Review Applied. It was subsequently publicized by 3D printer manufacturer Formlabs GmbH of Berlin in its marketing materials.

"This opens tremendous possibilities in our type of experiments," Osterwalder said in an email from his office at the Swiss Federal Institute of Technology (EPFL) in Lausanne, Switzerland.

"[Previously] experiments often had to be adjusted to what is possible. With 3D printing we are completely free in the design, and ​ we can simply think up a structure that we need, and then we make it."

Osterwalder said it took little more than a week to construct the beam splitter, including the CAD work and shipping the 3D part to and from the electroplating house, the Swiss company Galvotec GmbH which is headquartered in Schöfflisdorf, Switzerland.

Making the same piece in the EPFL mechanical workshop would have taken several months. As well, the beam splitter contains separate electrically conductive and insulating components, which would be difficult to align and mount.

Cost of the printed part was about $50, mainly for the resin, with the electroplating costing another few hundred dollars.

The beam splitter is just over a foot long, comprising three 3D printed segments. Resolution of the Formlabs Form2 printer is 0.025 millimeters, enough to give the part very fine dimensions, even after electroplating. The splitter stands up to harsh conditions as it separates molecular beams in the gas phase without the energetic molecules touching splitter surfaces. Experiments are run at close to absolute zero temperature. Voltages up to 10,000 volts are applied to the metal structure to manipulate molecules during the experiment.

Formlabs recently introduced its Form2 machine as an affordable printer to compete with much higher-priced SLA machines. It boasts a resolution of about 25 microns on the z-axis and about 100 microns for the x- and y-axes. Formlabs designs all its 3D printing resins in-house. It now has about 15 stock resins with properties ranging from biocompatibility to engineering performance. All resins are UV-cured after printing.

A 3D printed part must be very smooth if it is to be electroplated, according to Formlabs applications engineer Amos Dudley. Thickness of the electroplated metal, typically nickel or copper, can be as little as 5 microns, he said in a phone interview from Formlabs' Boston office. High metal thickness gives structural strength, but it sacrifices part detail.

Form2, launched in 2015, is a professional-grade stereolithography printer, which usually has finer resolution than less-costly fused deposition modeling printers or metal sintering.

Nickel plating can be chosen for high-wear, rigid surfaces, whereas copper gives excellent EMI shielding and heat conductance but less mechanical strength, explained Sean Wise, president and co-owner of Repliform Inc., a major electroplater based in Baltimore.

Repliform electroplates a lot of 3D printed parts for the aerospace industry where small electrical housings need EMI shielding. The industry also requires high-wear surfaces in some uses that nickel provides.

Repliform processes tens of thousands of parts per year, often placing them on racks to save space and handling. Wise said a rule of thumb is that the basic electroplating will add about 50 percent to the cost of a 3D printed part. He and his co-owner wife started electroplating SLA parts in 2001 and are seeing sales grow about 10 to 15 percent a year.

"We haven't focused on cost to bring the price down," he explained.

Despite costs, the metal/plastic combination is opening surprising new markets.

"People can make a statue of themselves by digitally manipulating photos to give a 3D bronze-like object," Wise said.

Formlabs' origins date to 2011 at the Massachusetts Institute for Technology. The business has grown to a 300-person enterprise with locations in the United States, Germany, Japan and China.