Each 3D printing process has its strengths and trade-offs. This article explores process resolution around text, thin walls, contours, pegs, and gaps by processes in FDM, FFF, SLS, MJF, PolyJet, and SLA. Check it out!
The CAD Model
The 3D CAD model highlights different features that could exist on your part. The goal was to bring 3D printing to its limits versus design for manufacturing, so we expected failures in most of our processes.
Below, we will go through the outcomes of each process used and explain why and what to avoid in your designs.
The 3D Printed Parts
We took high-resolution pictures to get to the nitty and definitely gritty of some of these features. This section will go from the coarsest feature detail to the finest.
FDM and FFF - Filament Printed Parts
Fused Deposition Modeling and Fused Filament Fabrication uses a plastic filament to build parts. The filament is melted through and extruder and zig-zagged back and forth to generate features from the bottom to the top of the print. FDM sweats the small stuff but excels at large format and structural designs versus thin and organic features.
- The dark grey ABS-M30 part was made using Stratasys Fortus equipment with the default setting for a .010" layer height. Even though this is an industrial machine, FDM typically has the coarsest feature detail. The small text under 10 mm, thin pegs under 2mm, walls under 1mm, and especially the gyroid feature suffered from unresolved, fragile, or rough features.
- In comparison, the desktop 3D printed FFF model in blue Prototyping PLA overall had better feature resolution, failing at walls thinner than 0.5 mm, pegs to 0.75 mm, and text below 5 mm. The gyroid resolved better than the industrial print but did have trapped supports that could not be removed.
SLS and MJF - The Generally Good Option
Selective Laser Sintering (SLS) and HP Multi Jet Fusion (MJF) are both powder bed fusion industrial 3D printing technologies that produce durable parts using fine plastic powder as a feedstock. Each of the parts below was built in the standard nylon 12 of their respective brands.
- The white SLS Nylon 12 resolved all features except the 0.25 mm peg. The grey MJF Nylon 12 had similar results but did not resolve the 2.5 mm text or the 0.25 mm peg.
- Both these processes are design forgiving because the powder-based process does not require traditional support structures, and the materials are ductile, allowing some flex before breakage. This makes them some of the most popular materials for prototyping and low-volume production, with the ability to take a high mix of designs.
SLA and PolyJet - Down to the Details
Resin 3D printing is known best for its ability to achieve fine details. The two examples below use resins but in different ways. Stereolithography (SLA) is popular for smoother surfaces and fine details. SLA uses a laser or other light source to cure liquid, growing the part from bottom to top. PolyJet uses resin via a dot-matrix print head that selectively deposits the material, which is immediately cured. PolyJet is best known for its ability to blend resins in the dot matrix, just like an inkjet printer, to produce vibrant colors and even multi-material prints.
- The grey Accura Xtreme SLA material had the best results overall in this feature challenge test with very crisp feature details and only the small 0.25 mm peg not resolving.
- The cyan Rigid PolyJet part had better detail than SLS or MJF but coarser vertical surfaces versus SLA. The small 2.5 mm text did not resolve fully and many of the thin pin features under 1 mm either did not resolve or broke (you can see a leaning pin in the image).
Conclusion
Each 3D printing process is another tool in the toolbox. If your design has fine features and needs a crisp result, for example, in a sales model or pattern for urethane casting, look at resin 3D printing like SLA. PolyJet is best when detail and colors need to be combined. For general purposes, SLS and MJF can hit many details and still remain durable. If you need details in filament, try the desktop FFF PLA over industrial FDM. Use industrial FDM when you have large or structural parts.
