Mold Craft Inc. has made ultrasmall injection mold tooling before.
It has built molds with complex shapes, and molds for sensitive resins.
But when it received an order for a medical pipette-shaped part with a wall thickness narrowing from 0.15 inch to 0.008 inch — to be made with ultrahigh-temperature resins and capable of moving from a single prototype tool to multicavity production — it was faced with all-new complexities.
“We weren't even sure this could be done, with this material, this thin-wall section,” said Justin McPhee, vice president of engineering for the Willernie, Minn.-based mold maker.
The fact that the company not only succeeded, but was able to see the mold run without a hitch throughout NPE2012 in Orlando, Fla., took expertise not only from within Mold Craft but collaboration across multiple companies. Mold Craft teamed with Beaumont Technologies Inc. for mold-flow simulation and to maintain proper flow in the tool; resin supplier Victrex Polymer Solutions for the use of its polyetheretheketone material; and press maker Sodick Plustech Co. Ltd.
The case presents a solid study for future development not only at Mold Craft, but for mold makers and molders moving further into micromolding, while technology demands for ultrasmall molds increase.
“The things that come into play when you get into these really challenging applications challenge all the technology that's out there,” said John Beaumont, president of Erie, Pa.-based Beaumont Technologies Inc.
Mold Craft specializes in small molds. Jim Liddell, director of sales, marketing and business development, described its expertise in producing molds for parts that can be held in a closed hand. It also produces those molds with up to 100 cavities.
Mold Craft originally took on the medical part expecting it to be a single-cavity prototype tool, but the project eventually involved a mold with four to eight cavities, McPhee said.
The part also had to be produced using PEEK. The combination of requirements for an ultrathin wall and high temperature made it clear within a day that Mold Craft would need input from other firms.
A hot-runner and gate system would be crucial to the part, he said. Melting variations would lead to a high number of defective parts.
Mold Craft had previously worked with Beaumont Technologies, an engineering and technology firm with the MeltFlipper mold-flowing system, and turned to it to help design the mold.
Beaumont has developed its own proprietary mold-flow software, Veri-flo, which uses data collected by running the specific resin a molder will use, and how that material behaves in a series of complex molds. That provides more detailed information, John Beaumont said.
Part of the difficulty in creating very small molds is that those molds pose unique processing issues — issues that companies focusing on large-scale production do not necessarily study, he said.
“No one is focused on the guy buying 50 pounds of resin,” Beaumont said.
So micromolding production needs precision mold makers like Mold Craft, but also access to new data, he said.
Using Veri-flo, Beaumont can develop specific mold-flow simulation using PEEK on a Sodick Plustech press. Sodick, based in Yokohama, Japan, has become a preferred press maker for micromolds. Beaumont Technology uses two Sodick presses in its Veri-flo process.
The combination of Mold Craft's precision manufacturing, Beaumont's simulation process and use of MeltFlipper to control the flow guided the final design.
When it was time to run sample parts on the prototype mold, Mold Craft shipped it to Sodick's North American operations in Schaumburg, Ill. The tests went off flawlessly, Liddell said.
“I got in an airplane to fly to Chicago in the morning, and by the time I got there, they'd already run the tests and everything was done,” Liddell said.
The mold-flow analysis also sped development of the final production tool with multiple cavities.
The success prompted Sodick to run the tool nonstop on the NPE floor, which generated interest for each of the firms involved.
And the success will also mean further collaboration, as Mold Craft expects the demands for tighter tolerance, higher temperatures and more-complex parts in very small molds will continue.
“We're exploring more options and opportunities,” McPhee said. “We have a couple of other very, very small-part [makers] that plan on using all of us for their components.”