Cool and Wait

Until costs subside or production increases, additive manufacturing will remain a niche process.
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As the tool and die industry searches for ways to accommodate a greater demand for its services, innovations based on 3-D printing printing technology may offer a solution to ease the capacity constraints facing toolmakers. The process is used to create a physical object from a three-dimensional, computer-generated drawing.

Following the exterior and interior contours of the drawing, lasers sinter (or fuse) a material into slices ranging in thickness from a few microns to one-quarter of a millimeter. Thousands of slices are built upon each other, eventually creating a 3-D object. Introduced in the late 1980s, additive manufacturing has been used mainly to create plastic parts, but recent developments now make it possible to use the process on a variety of metals.

Manufacturers have been using 3-D printing technology since the late 1980s, but even with more powerful computers and machines, the process today is still slow and cumbersome. Photograph courtsey of Linear Tools and Engineering

Linear Tool and Engineering in Livonia, a leading provider of 3-D metal printing in the aerospace, medical equipment, agriculture, and automotive industries, uses additive manufacturing to solve a problem inherent to plastic injection molding: how to shorten the time needed for a part to achieve a uniform temperature before it can be removed from its mold. If this “cycle time” can be reduced, bumper fascia and door panels can be produced more quickly.

The process is tricky. “Before you open that mold, you want to make sure you don’t have a massive variation in temperature, because the area of the mold that’s hotter will cause the part to shrink and warp,” says Lou Young, Linear’s director of new business development for tooling and manufacturing.

Toolmakers have traditionally reduced hot spots by drilling water channels into the molds, but the process is limited because straight channels can’t conform to the often-complex geometries of a mold. To reduce the cooling period, Linear and other tooling shops have started adding metal inserts to boost so-called “conformal” cooling.

“We can print an insert for a mold with curlicues, pretzels, and swirls that let the water get close to the hot spots,” says Paul Parzuchowski, Linear’s marketing and business development director. “We have demonstrated anywhere from 15 percent to 60 percent cycle time reduction because the tool will cool off that much faster. If you have 100,000 square feet of space committed to manufacturing and you need to increase capacity to meet future demand, I’ve just shown you how to do that and you haven’t invested a dime (in new space).”

Still, the added patterns necessary to promote conformal cooling carry a high price tag.

Linear expects additive manufacturing to be a $20 billion business by 2020, with 3-D metal printing claiming 10 percent of the market. “The auto industry can take great advantage of this service, but they’re concerned about production quality. Historically, automotive tends to be slow to move toward manufacturing innovation,” Parzuchowski says.

“The OEMs are all making business cases and justifying the increase in tooling costs,” Young adds. “You could have a $300,000 injection mold done with conventional cooling lines, and that same mold with conformal cooling might cost $450,000. They’re all trying to figure out if the cycle time reduction will cover the increased costs. We just had one of the biggest Tier 1 companies in here to learn about conformal cooling. They’re all interested, they all understand the benefits, but they need to make the case to their executives.” db

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