3D printing and injection molding: mapping the best of both worlds


The acquisition of Collider and its Orchid printer technology by industrial 3D printing company Essentium, and Professor Steve Stagon of the University of North Florida (UNF) patent for a 3D printed mold raises the bar in the quest to reduce or eliminate costly tooling while optimally producing workpieces in larger volumes.

By acquiring Collider’s technology – which prints a thin, soluble photopolymer shell and fills it with a traditional thermosetting polymer, all in the same build chamber – Essentium is firmly committed to programmable tooling via digital light processing. (DLP).

“We believe that the programmable tooling and other parts of our Orchid platform will contribute to the polymer-based additive 2.0 revolution,” said Graham Bredemeyer, director of photopolymer at Essentium, based in Pflugerville, TX. . The technology produces “parts that mimic the strength and surface quality of legacy technologies such as injection molding and CNC machining, but in a fraction of the time.”

Technology accelerates development and production times

In terms of production goals, Essentium prefers “to think of the activity in groups of machines needed to produce 50 to 1,000 parts per day and more,” added Bredemeyer. “We see this as speeding up development and volume production times for our customers by months or even years, particularly in the medical, military and transportation sectors. “

3D printing allows the design and production of complex geometries.

This best of both worlds approach harnesses the main advantages of 3D printing and molding, explained Bredemeyer.

“The DLP direct printing process produces parts as good as the resin used. Today, photo resins are not as strong as standard materials used for injection molding or CNC machined parts. Collider technology uses the broader class of thermosetting polymers as the basis for finished parts and, therefore, does not suffer from these limitations.

The process overcomes the challenges of 3D printing plastic molds

Meanwhile, Stagon’s patent for a printed injection mold with optimized coatings and cooling channels targets an idea “that a number of groups have looked into,” he said: to produce a mold in polymer whose performance matches metal molds as much as possible to save time and money.

Stagon’s molds target small to medium-sized batches and part families with slightly varied geometries, the Jacksonville professor said. “In this area, traditional mussels are not profitable – too much capital investment for small batches.” But attempts at printed polymer molds suffered from several problems:

  • Hot molds tear and quickly loses edges and surface features. “You can only take out a handful of parts on each mold, which reduces the margin when changing tooling and preparing new printed tools,” Stagon explained.
  • Poor cooling means cycle times are 10 to 100 times longer, and solidification and uniformity can become problems. “The fully printed polymer molds behave very differently due to the differences in heat transfer, and our partners were spending too much time tuning the processes – again reducing the margin. “
University of North FloridaDr Steve Stagon, Associate Professor of Mechanical Engineering at the University of North Florida
UNF Associate Professor of Mechanical Engineering, Dr. Steve Stagon, received a US patent for a 3D printed injection molding tool with improved heat transfer and mechanical strength.

Professor UNF’s solution? Create a process that preserves surface characteristics “beyond a handful of parts and improves thermal conductivity closer to a point to reduce injection parameters. In large runs, metal molds are always and Our work brings the small batch of aluminum molds a little closer together and speeds up the workflow with fewer settings. “

For the coatings of its molds, Stagon borrowed the technology of traditional molds.

“We combine electroless and vapor deposition, or ‘sputtering’, to first ‘strike’ the surface of the mold to make it conductive. We then place on 1 to 50 microns of eNi, NiP or CoP. This gives us a very strong layer which conducts heat very well. In addition to this, we have put classic mold coatings like PTFE Ni and Autocatalytic Ni-Boron. By making the surface slippery and having good lubricity and non-stick properties, we are able to preserve the thick structural coating longer and relieve the adhesion between the polymer and the veneer.

Meanwhile, 3D printing allows Stagon to place the cooling channels close to the elements and position them relative to the elements of the interior mold. “Thanks to the strength of the metal coatings on the surface, we are able to reduce the thickness to a centimeter or less, in some cases when the injection pressures are kept low. We are working on getting good temperature profile data for this, but we have seen the cooling times decrease by a factor of two in our early prototypes. “

As the pandemic has slowed development, Stagon is eager to forge partnerships to develop and test the technology outside of the lab. “Our entry point should be in the area of ​​existing part molds. If you would like to consider a partnership, send an email to Stagon.


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