CFdesign Leads to a Radical New Mold

By Bob Cramblitt

A CFdesign image shows the pressure within a cooling system – blue is the lowest pressure.

Radical is not a word one expects to hear from a plastic injection molding company. Yet, it pops up more than once in conversation with Paul Mailloux, the CAD/CAM application engineer for NyproMold of Clinton, MA.

  NyproMold designs and builds high-precision molds used for products such as cell phones, electronic equipment, consumer, and medical devices. At NyproMold, radical is most often used to describe mold cooling breakthroughs made possible by upfront CFD using CFdesign software and the latest in laser sintering technology from CONCEPT Laser of Lichtenfels,  Germany.
 
Removing the Guesswork
CFD, FEA, and injection-molding simulation software has always been part of the NyproMold design and engineering process, helping the company make decisions and predictions prior to actual manufacturing. But with CFdesign software from Blue Ridge Numerics, CFD is factored in at the early product-development stages, where it is most valuable in determining the feasibility of design options.

  Integration between CFdesign and Pro/ENGINEER software from PTC enables NyproMold to conduct iterative design studies without any translation, conversion, or data loss. Volumes, void-filling, boundary conditions, and material properties are assigned automatically in CFdesign. Associativity of all geometry is maintained as the assembly moves between CAD and CFD iterations. This close relationship between CAD and upfront CFD is enabling NyproMold to replace conjecture with confirmation.

“NyproMold brings many, many years of cooling expertise to the table and can often predict what is needed for good cooling circuits,” says Mailloux. “CFdesign can confirm and/or correct the original predictions. It has replaced guesswork with accurate, concise data that gives us the confidence we need to design and build molds right the first time. This is extremely important to us as there is never enough time or capital to do the same job twice.”

A CFdesign image shows the pressure drop throughout the cooling system; vectors indicate the flow direction.

Manufacturing for Radical Cooling
While CFdesign provides the ability to explore new designs on the front end, laser sintering enables NyproMold to fully realize those designs in the physical world.

  Laser sintering is a fusion process that uses 3D CAD data to produce large-volume components layer-by-layer. Complex component geometries can be manufactured without tools, and optimally cooled mold inserts allow parts to be produced without distortion. Parts produced with laser sintering are comparable to traditionally machined parts in terms of steel density and hardness,  according to Mailloux.

“Laser sintering technology allows us to create parts and inserts that contain complex conformal cooling circuits that are otherwise impossible to create with conventional manufacturing techniques,” says Mailloux. Conformal cooling is a methodology that uniformly cools complex cores and shapes in molds, offering large savings in cycle times and increased part quality.

Reducing Cycle Times
Mailloux cites a before-and-after contrast for a high-cavitation tool as an example of the big dividends from combining upfront CFD and laser sintering.

  The tool was initially designed with traditional circuits before NyproMold implemented CFdesign software and the laser sintering system. The second time the tool was designed, a new cooling circuit was developed after using CFdesign to experiment with several conformal cooling scenarios.

“The ability to overlay and compare various iterations of cooling circuits within CFdesign to determine the best cooling concept was extremely valuable to us,” says Mailloux. “Then, there were the fast processing and quick results: Even during the computations, dynamic results were available for review and interaction. This enabled early decision-making prior to actually finalizing the computations.” 

Using the CFdesign simulations, NyproMold confirmed the best cooling concepts and perfected the cooling circuits prior to manufacturing. “We basically removed all guesswork and rework upfront, and were able to then take full advantage of laser sintering at the back end,” says Mailloux.

  The improved cooling of the final high-cavitation tool reduced cycle time by more than 40 percent, from 23 to 16 seconds.

CFdesign images show the fluid flow path in the cooling system. At left is a zoomed-in view with the trace style set to lines and colored by pressure. The image on the right shows the entire system, with ribbons as the trace style and pressure distinguished by colors.

“In terms of injection molding, this is a radical improvement amounting in tremendous annual savings to our customer,” says Mailloux. “Only CFdesign could have led us down this decision-making course to reach such a successful result.”

Impact on Customer Satisfaction
Although customers rarely see upfront CFD analyses, Mailloux says they have a major impact on customer satisfaction.

“We have a far greater confidence that timelines will be met and first-off parts will be acceptable,” he says. “We are able to provide the best cooling scenarios and therefore improved cycle time, part quality, and process windows that would otherwise be unachievable with mere guesswork.”

  With the combined capabilities of upfront CFD and laser sintering, NyproMold is adding an unexpected new meaning to “radical,” making it synonymous with “rest assured.”

More Info:
Blue Ridge Numerics

CONCEPT Laser GmbH

NyproMold

PTC

Bob Cramblitt is principal of Cramblitt &  Company in Cary, NC. He writes about technologies that dramatically impact the way products are designed, engineered, and manufactured. Comments should be sent to [email protected].