As we’ve previously outlined, there are significant time and monetary costs associated with post processing of metal 3D prints. Much of those costs are incurred around support material as it eats up stock material and is time-consuming to remove. Having to use support pillars also limits part geometry and how many parts can be printed at a time. Getting rid of support pillars would come with a slew of benefits. So that’s what Velo3D did with their SupportFree system and it boosted weekly production rates by over 60%.
In powder bed metal 3D printing, support pillars don’t hold overhanging areas up so much as they hold the entire object in place. That’s because overhangs are already supported by the powder bed, but flat metal parts tend to warp during the sintering process as the granules of metal powder are rapidly heated and cooled, so support pillars help to prevent that warping by serving as anchors and heat sinks. There are other ways to combat that warping though, such as minimizing flat layers and tightly controlling all of the print processes.
With SupportFree, all parts are angled so that only a single point of a part is facing downward during printing, like balancing a cube on a corner; if no such point exists on a part, a corner is temporarily added to an outer edge and then removed after printing. Orientating each part so that it begins at a small point and grows outward as it goes up means the whole part can act as a heatsink, reducing the uneven heating and cooling patterns that cause warping. Beyond that, feature-specific processing allows the printer to affect its parameters when printing the starting points for each part to avoid warping as it forms. Some of the controlled and tracked parameters are chamber temperature, laser alignment, beam stability, laser focus, thermal sensor alignment, and powder bed quality.
Those same metrics are monitored in Velo3D’s quality control system called Assure. Velo3D solutions engineer Will Hasting explains, “If the machine is nominally in spec when the build starts and it remains in spec all through the build, then that is the basis for validating part quality if a quality part has been produced that way before.” That can really cut down on the costs that come with part validation.
When the SupportFree system was applied to an aircraft bracket, a single print went from holding 18 units to 220 units. After factoring in the increased print time for more units per run, the production rates go up to 147 units per week compared to 90, an increase of 61%. And that doesn’t include all of the savings because it doesn’t consider the post processing time avoided by not having to remove support pillars. “There is also less touch labor per part in the method without supports,” said Hasting.
Velo3D has essentially made Metal Powder Bed Fusion work like Selective Laser Sintering, the powder bed technology used to print polymers like polyamide. After printing is complete, parts can simply be lifted out of the vat of powder rather than having to be sawed off the baseplate like with most metal 3D printers. The SupportFree system enables for more freedom in design because overhangs don’t have to be avoided. Additionally, designers can include larger internal diameters and print parts with higher aspect ratios. It’s hard to believe so many advantages come with just doing away with support pillars.
Featured image by Velo3D