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Printing Features You Can’t Machine

Linear Mold & Engineering (Livonia, MI) builds sophisticated injection molds and other tools using additive manufacturing (AM). They’re using direct laser melting with nine different metals, but their big one for high-performance tools is maraging steel.

“It’s a good steel for making tools,” says Lou Young, “It can be hardened similarly to H13 or S7, up to 54 to 56 Rockwell C. It has better corrosion properties than P20 tool steel, and it welds pretty well. We like it especially for injection tools.”

Having a steel that’s practical for making molds, and that can be direct-laser-melted, has allowed Linear Mold to exploit AM’s ability to produce otherwise impossible shapes. In particular, they design internal cooling passages that result in a mold with superior performance.

“In some cases the cooling allows us to cut cycle times down 50% from conventionally built tools,” says Young. “Improving cycle time anywhere from 20 to 50 percent is huge.” The upshot is that AM-produced molds can be up to 50% more productive, justifying a premium price.

The screen shots tell the story. These are thermal-analysis models of tools with conventional cooling (left) and with the AM-produced curved, internal cooling channels (right). The colors show the difference in cooling capability of each design.

“I’m told that our 14 AM machines represent the largest such capability in the U.S. – maybe in the world,” says Young. “Some of the largest manufacturers in the country are looking at replacing their conventional molds with these high-performance molds. Things are looking very bright.”

Linear Mold & Engineering