Bigger, Faster, Stronger: New Projector 3D Prints Powder Plastic Parts Better than SLS

Thanks to a new infrared (IR) projector from digital light processing (DLP) manufacturer Visitech, it’s now possible to 3D print polymer parts with results that exceed those of selective laser sintering (SLS). Not only can the Norwegian firm’s direct image sintering (DIS) produce 3D printed parts faster and with larger build volumes than traditional SLS, but, based on testing from a third-party lab, DIS components are actually stronger than those made with SLS. The potential for polymer powder bed fusion (PBF) with the new technology is significant.

Visitech’s Projector-Based Powder 3D Printing

In 2021, Visitech announced its DIS technology, which relies on 120-watt DLP IR projectors rather than a laser. Instead of fusing polymer powders point by point, the use of a projector makes it possible to fuse an entire build layer at once, thus increasing print speed, specifically at high packing densities.

Visitech successfully achieved polymer powder bed fusion using a powerful DLP-based IR light engine to project the powder-melting image in one shot – which is faster than traditional SLS methods. Image courtesy of Visitech.

With the unveiling of Visitech’s LRS MCx-NIR projector, machine builders curious about the unique technology inquired about the print quality of DIS. This led Visitech engineers to further examine the physical and mechanical properties of items made with DIS.

Strength in DIS vs SLS 3D Printing

In performing what the company claims to be comprehensive material quality testing, it was founded that DIS achieved “better-than-expected” results with standard nylon materials, including a smooth surface finish.

Visitech R&D Manager Endre Kirkhorn (right) and Product Manager Sebastian Aske point out how Direct Image Sintering (DIS) produces improved tensile and impact strength for PBF-printed parts when compared to SLS. Image courtesy of Visitech.

More importantly, when performing standardized Charpy and tensile strength stress tests and independent lab, found that components made with DIS performed better than identical counterparts made with SLS. This was impacted by the way that the parts were oriented in the build volume. Visitech R&D Manager Endre Kirkhorn explained:

“Test results conclude that parts printed using DIS, when compared directly to legacy SLS, show significant improvement in both tensile strength and Charpy tests. Object orientation does play a role here. Optimal orientation produces the most significant improvement, but even suboptimal orientation for the test part prints produced high-quality test results compared with SLS.”

Otherwise, Visitech explained that DIS is similar to traditional SLS in that powder handling and re-use are the same and the print setup is comparable. The company suggested, however, that surface smoothness was better with DIS-printed objects.

Batch Size for DIS vs SLS 3D Printing

In addition to increased speed, DIS also enables larger print volumes. The new, liquid-cooled projector was created as Visitech was pioneering a method for scrolling DLP, in which multiple projectors are stacked to increase throughput. This setup, powered by software for stitching separate projector images together, can be used with Visitech’s DLP projectors for photopolymers, as well as the new DIS projectors. In turn, machine builders can create systems for 3D printing bigger parts or a larger number of parts simultaneously.

“Bigger building areas, more robust and smoother parts, printed faster, with higher resolution, at higher packing density. That is the essence of what our DIS technology achieves for machine builders who adopt it,” said Kirkhorn. He points to high-resolution professional-level throughput at large building areas as the strongest argument for choosing DIS over SLS. Small prototype 3D printing, however, still benefits from a sounder price/performance by traditional SLS.

DIS 3D Printing in the Market

According to the “Polymer Additive Manufacturing Markets and Applications: 2020-2029” report from SmarTech Analysis, polymer PBF is projected to be the “highest grossing polymer print technology” by 2030, edging out over material extrusion and vat photopolymerization processes. Specifically, SmarTech expects the segment to generate over $2 billion by 2030.

The polymer PBF market is already being shaken up by other non-laser-based processes, including Multi Jet Fusion (MJF) from HP and high-speed sintering from Stratasys and others. These inkjet processes rely on a combination of IR-sensitive inks deposited onto polymer particles that are then fused with IR lamps.

VISITECH’s LRS-MCx Reference Motion stage can use up to four UV DLP projectors or two NIR projectors. Image courtesy of Visitech.

They do offer higher throughput than SLS, but entire layers are not printed at once in the same that Visitech’s technology allows. Given the speed and scale at which MJF is being adopted, it would be interesting to see how DIS compares in terms of quality and throughput. With a multi-projector scrolling setup, it’s quite possible that DIS could give HP a run for its money.

For this to happen, machine builders will have to first get their hands on the technology. Visitech will be opening up orders for DIS systems in Q4 2022. Typical DIS systems are made up of individual or multiple LUXBEAM Rapid Systems LRS MCx-WX-IR projectors along with LAMA or LAMA Pro software. Machine builders provide their own powder handling and heating setups, with X and Z motion system. Visitech supports the DIS integration process and can provide reference and custom motion system configurations.

The new DIS technology will be presented at Formnext in Frankfurt, Germany November 15-18, along with Visitech’s new 8K DLP UV projector. Using a customized optical actuator to shift the image of a DLP device four times per exposure, the 8K projector is able to address 32 million pixel positions.