Novel 3D Printing Technique Combined with Micromolding Slashes Production Timelines

Austrian startup NanoVoxel reports that it can produce high-precision micro-scale parts in just two weeks. The breakthrough is made possible through a combination of novel two-photon 3D-printing technology developed by fellow Austrian startup UpNano and a 15-t MicroPower injection molding machine from Wittmann Battenfeld.

Femtosecond laser acts on photosensitive resin.

UpNano’s 3D printer is based on the principle of non-linear absorption of photons, explained NanoVoxel Chief Technical Officer Martin Ganz in a technical report distributed by Wittmann Battenfeld. The two-photon polymerization process, branded as 2PP by the company, uses a narrowly focused femtosecond laser beam to excite a photosensitive resin, causing it to polymerize and solidify. Unlike conventional 3D printing, however, 2PP achieves full control of polymerization in the z axis, explained Ganz, producing precise, round holes and cavities. The process “offers unparalleled precision and resolution, enabling the creation of complex 3D micro-structures with sub-micron accuracy, even down to the nanometer range. This makes it ideal for applications requiring particularly intricate details with high surface quality,” said Ganz.

A 3D-printed array of micro-needles. Image courtesy of NanoVoxel.

Parts can be printed within hours from a CAD file with tolerances under 1 micrometer (µm), structures down to 200 nanometers (nm), and surface finishes with average roughness better than 10 nm. While the process enables the production of geometries that would be impossible via injection molding, it is not suited for volume production. It would be cost-prohibitive to make parts larger than a few millimeters. NanoVoxel broke this logjam by combining 2PP printing with micromolding, which is its core business model.

Related:Wittmann Talks Turkey at NPE

Overcoming volume production limitations.

NanoVoxel uses 2PP printers to rapidly produce high-precision molds that replicate the precision and resolution of 2PP in micro parts. Small detailed structures can be accurately and repeatably molded with tolerances in the micrometer range. Moreover, 2PP 3D printing can precisely create mold cavities that enable the production of larger parts with single-digit micron features that otherwise would be too time-consuming, expensive, or even impossible to produce, according to Ganz. One recent application is the development and production of an endoscope for Zürich-based aiEndoscope.

Individual prototype segments of the endoscope initially were printed in various design iterations for testing and optimization. Upon validation from the customer, NanoVoxel quickly molded the parts for functional and mechanical testing. All of the manufacturing process and design iterations for this complex medical device were completed within five weeks, according to the company.

MicroPower injection molding machine from Wittmann Battenfeld. Image courtesy of Wittmann Battenfeld.

NanoVoxel relies on a 15-t MicroPower injection molding machine from Wittmann Battenfeld to leverage high-precision molds, noted Ganz. The 150-kN clamping force enables the cost-effective production of small and micro-sized parts with maximum precision and accuracy, and a two-stage screw-piston injection unit with thermally homogenous shot volumes from 1.2 to 6.0 cubic centimeters makes it possible to produce precisely molded parts in exceptionally short cycle times, added Ganz.

Capabilities beyond rapid tooling.

The dynamic duo of 2PP printing and micromolding is not limited to the rapid tooling process. NanoVoxel can print directly on parts in materials other than plastics, including glass, ceramics, carbon substrates, and metals, manufactured via other processes. The company can also combine different materials and offers customization suited for rapid prototyping, product development, and mass production. “This enables customers to imprint detailed functional features directly onto bulky and larger parts obtained from more efficient processes. Initial applications have been successfully applied in the microfluidics world, where NanoVoxel printed unmoldable features onto commercial chips, using its advanced printing process only where needed,” said Ganz.

“NanoVoxel´s efficiency with the micro-manufacturing process unlocks new creative avenues for designers and engineers across diverse industries and revolutionizes the way in which to approach design and fabrication of intricate, customized, and functional micro-scale parts,” added Ganz.