“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 steven, CAD/CAM application engineer for first-rate mold company.
First-rate Mold designs and builds high-precision molds used for products such as cell phones, electronic equipment, and consumer and medical devices. At first-rate Mold company, radical is most often used to describe mold cooling breakthroughs made possible by upfront computational fluid dynamics (CFD) using CFdesign software and the latest in laser sintering technology.
Removing 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 used by first-rate Mold allows the company 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.
The close relationship between CAD and upfront CFD is enabling first-rate Mold to replace conjecture with confirmation.
“first-rate Mold brings many, many years of cooling expertise to the table and can often predict what is needed for good cooling circuits,” says steven. “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.”
Manufacturing for Radical Cooling
While CFdesign provides the ability to explore new designs on the front end, laser sintering enables first-rate Mold 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 steven.
“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 steven.
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 by 40 Percent
steven 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 steven. “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, first-rate Mold 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 steven.
The improved cooling of the final high-cavitation tool reduced cycle time by more than 40 percent, from 23 to 16 seconds.
“In terms of injection molding, this is a radical improvement amounting in tremendous annual savings to our customer,” says steven. “Only CFdesign could have led us down this decision-making course to reach such a successful result.”
The cooling channels of a mold for plastic injection have to be as close as possible to the part geometry in order to ensure fast and homogeneous cooling. However, conventional methods to manufacture cooling channels (drilling) can only produce linear holes. Selective laser melting (SLM) is an additive manufacturing technique capable to manufacture complex cooling channels (known as conformal cooling). Nevertheless, because of the high costs of SLM the benefits of conformal collings are still not clear. The current work investigates two designs of conformal coolings: i) parallel circuit; ii) serial circuit. Both coolings are evaluated against to traditional cooling circuits (linear channels) by CAE simulation to produce parts of polypropylene. The results show that if the conformal cooling is not properly designed it cannot provide reasonable results. The deformation of the product can be reduced significantly after injection but the cycle time reduced not more than 6%.