3-D Printing’s Promise—and Limits

Date: 02-06-2014
Source: The Wall Street Journal

So Far It’s Proving to Be Great for Prorotypes and Small Production Runs, but Not So Much for Bigger Jobs

turtler transmitter 3dRest Devices used 3-D printing to make the “turtle” transmitter in its onesie monitor—until it got a big order and switched to injection molding. Mimo

Manufacturers are finding that a revolutionary technology has its limits.

According to enthusiasts, 3-D printing was supposed to rewrite the rules of how things get built. Forget building new factories, or outsourcing production to China. The compact devices would launch a manufacturing renaissance centered in people’s living rooms and garages.

It may yet do all that. But for now, here’s the reality: The technology works very well in some settings—but it doesn’t scale very well. Product designers and manufacturers say that 3-D printing beats traditional methods for jobs involving complex designs or limited production runs. But if companies need to crank out thousands of products in a short time, traditional methods are faster and more cost-effective.

“If you need more than a few thousand” items, says Denis Cormier, a professor of industrial and systems engineering at the Rochester Institute of Technology in New York, “you’re probably better off doing injection molding of a plastic part.”

Ramping Up
The 3-D printing process works something like inkjet printing of paper documents: The machines build objects by spreading microscopic layers of plastic or metal that are fused by lasers or ultraviolet light. Designers can create a computer model of the part they need and have a physical version within minutes or hours.

Square HelperChris Milnes has stayed with 3-D printing to turn out as many as 100 Square Helpers a day.

But it’s not fast enough when companies need to produce on a mass scale. Thomas Lipoma and a group of classmates from the Massachusetts Institute of Technology were using 3-D printing technology to manufacture the Mimo, an infant’s onesie with a built-in sensor that lets parents monitor the breathing of their newborns. Then Babies “R” Us ordered 7,000 pieces, and their MakerBot 3-D printer simply couldn’t produce the items fast enough.

“We did the entire concept through testing in about a month” using the 3-D printer, says Mr. Lipoma, but when production ramped up from 200 pieces a week to a planned 50,000 a month, “that’s a lot to do for a MakerBot.”

So, their startup, Rest Devices, turned to traditional injection molding to make key plastic parts. “The parts come out of the injection molding once every 15 to 20 seconds, and with the MakerBot, it’s once every 15 to 20 minutes,” says Mr. Lipoma.

Greg Pishko had a similar experience with 3-D printing when he created a floating drink holder, which he’s trying to sell as an accessory for pool parties in Las Vegas.

3-D printing helped Mr. Pishko, who designs health-care appliances for neurologists at the Oregon Health and Science University in Portland, quickly turn his concept into a prototype and get the attention of hotel chains. But he’s going with injection molding to fill orders. It’s faster, for one thing, and in this case it’s also much cheaper because of the amount of raw material involved. 3-D printing would have cost about $100 per drink holder, compared with $2 for injection molding.

Focusing on Strengths
Some makers of 3-D printers don’t argue with the critiques. Devices like MakerBot’s are meant to help designers and engineers test ideas and speed the development of products, not necessarily replace large-scale manufacturing, says Jenifer Howard, a spokeswoman for the company, a subsidiary of Stratasys, one of the largest manufacturers of 3-D printers and systems.

“When we look at the cost-value benefit” of 3-D printing, says Cathy Lewis, chief marketing officer of 3D Systems, another leading manufacturer of 3-D printers and systems, “we don’t see it eliminating traditional manufacturing.”

The crossover point at which point traditional manufacturing is more effective usually comes at 5,000 pieces, Ms. Lewis says. So if a company is making a mass-appeal product with a huge production run, such as a Barbie doll, it would probably stick with injection molding.

But a 3-D printer has other advantages, Ms. Lewis says. With injection molding, companies must create a different mold for every different part they want to produce. And if the specifications for a part change, they must come up with a new mold for it. With 3-D printing, there’s no mold—just a computer model of the part that can be updated at any time.

What’s more, Ms. Lewis says, 3-D printing can easily handle complex designs and print an item with multiple parts all at once. With injection molding, parts often need to be manufactured separately and then assembled.

Chris Milnes discovered the advantages of 3-D printing when he was deciding how to manufacture the Square Helper—a plastic clip the size of a quarter that holds a credit-card reader in place on an iPhone or iPad. Mr. Milnes traveled to China to see how cheaply he could have the clip made, but was put off by costs of $6,000 for the tooling to build an injection mold, and the 25 to 30 cents each unit would cost him.

Instead, he turned to a MakerBot Replicator 2. “I bought a MakerBot for $2,000, and the plastic costs me 3 cents apiece,” Mr. Milnes says. “There were no pros and cons, only pros and pros.”

Using a 3-D printer also makes it simple to adjust the part when Apple updates the iPhone. “I just change a line in my file, and I can print the new part,” Mr. Milnes says. So far, he says, he has sold about 2,000 clips for $7.95 each.

3-D printing is also becoming invaluable for military applications, says Ms. Lewis of 3D Systems. Military hardware can have a working life of 30 years or more, so it’s far less expensive to 3-D print parts as needed than to keep the necessary tooling around for the entire life cycle of the item.

For instance, workers assembling the $116 million F-35 jet fighter use hundreds of 3-D printed tools to assemble the plane, with numerous 3-D parts in development, said Mike Rein, a spokesman for the plane’s maker, Lockheed Martin Corp.


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