TwoCure Method Enables Resin 3D Printing Without Supports

SLA 3D printing is wonderful for many reasons, such as speed and the ability to produce high-resolution objects. It does tend to require some post-processing, though, particularly support removal. Supports tend to be necessary for SLA 3D printing, but a group of experts from the Fraunhofer Institute for Laser Technology ILT and Rapid Shape GmbH have developed a new resin-based, SLA-like 3D printing process that doesn’t require supports that have to be laboriously removed.

The two organizations worked together as part of a Central Innovation Program for SMEs project funded by the German Federal Ministry for Economic Affairs and Energy.

The idea, Andreas Hoffmann, M. Sc., Photonic Organic Printing, Fraunhofer ILT tells 3DPrint.com, came up a few years ago when he and his colleague Holger Leonards “came up with the idea to get rid of supports by ‘freezing’ the resin… After that we did a few simple feasibility tests and tried to get IP protection,” a process that he explains is still ongoing.

“For the new technology the requirements on the photo resin are a little bit different from current lithography based technologies. Apart from the properties of the cured polymer we have to fulfill the requirements on the freezing/melting temperature and miscibility/segregation of the resin components during the process. This is the reason why the first application was jewelry production via lost moulds. Prospectively, we want to develop additional resins for more advanced applications like otoplastic or dentals. Integration of 3D-printing into production chains is also an upcoming challenge on 3D-printing in general. Here, the new process may offer some advances too,” Hoffmann explained to 3DPrint.com.

Like with SLA, liquid resin is cured layer by layer; an LED light is used as the light source like in other 3D printers developed by Rapid Shape. However, the new process not only doesn’t require supports, it doesn’t require the printed components to be connected to the print platform at all.

“Furthermore, we can create 3D components directly in the build volume, anywhere we choose,” said Fraunhofer ILT Project Manager Holger Leonards. “The components no longer have to be built on platform. Because the total build volume is being used more efficiently, each 3D printing job can create significantly more parts.”

The liquid resin is solidified in two different ways: photochemically with light and then thermally with cold.

“The material is applied warm and then irreversibly cured by light. At the same time the cooled installation space ensures that the thermoset component being created layer by layer freezes to form a block with the resin that has solidified like wax,” said Leonards.

The user can then liquefy that block at room temperature so the surrounding material melts away, leaving only the 3D printed component, which just needs to be cleaned and post-cured. Eventually the team wants to be able to automate those steps as well.

The process is called TwoCure, as two different curing processes are used. The idea came out of a joint workshop between Fraunhofer ILT and Rapid Shape. The material and photochemical process were developed by Fraunhofer ILT, while the procedure and systems technology were created by Rapid Shape. The first prototype of the system has been built and should soon be ready for series production.

TwoCure was tested with models for jewelry, such as rings.

“Jewelry manufacturers have so far used supports to create their models and then removed them in a very laborious process before smoothing the surface,” said Andreas Schultheiss, Founder and CEO of RapidShape. “These last two production steps are expensive and superfluous. The new process means they will not be needed in future.”

This is good news for all users of resin-based 3D printing technology; the tradeoff for the speed and detail of SLA 3D printing has always been the work involved in post-processing. TwoCure eliminates much of that work while retaining the features that make resin-based 3D printing so appealing for so many applications.

While much of the work we’ve seen so far from Fraunhofer has led to innovations in metal technologies and new advanced hybrid manufacturing techniques, this resin-based research represents an interesting take on 3D printing addressing another set of materials.

Fraunhofer ILT will be presenting the TwoCure process at formnext, which will be taking place in Frankfurt, Germany from November 14-17. Fraunhofer ILT will be in Hall 3.0, Booth F50. 3DPrint.com will be on-site in Frankfurt to continue reporting on all the latest announcements during the show.

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Editor’s Note: This article updated on November 3, 2017 from its initial publication to include insights from Andreas Hoffmann.

[Source/Images: Fraunhofer ILT]