Because Protolabs offers a number of digital manufacturing services, the staff track the continuing advancements in additive manufacturing (also known as industrial 3D printing), injection molding, machining, and materials. Additive manufacturing, in particular, continues to undergo frequent advances. Recently, Applications Engineer Eric Utley offered his observations of the ongoing developments in additive technology.
1.Which additive technologies are leading the way?
Direct metal laser sintering (DMLS) is currently the industry leader for the production of metal parts. Historically, selective laser sintering (SLS) was the best-suited technology for production plastic parts, but because of the significant speed advantage of the HP Multi Jet Fusion (MJF) system, that 3D printer is quickly gaining ground. As HP expands the capabilities of this printer, (material options, colors, and so on) they will continue to gain ground here.
But there are a lot of new and exciting technologies that either came out recently or are on the horizon. Carbon’s CLIP technology prints plastics and elastomers very fast and has impressive material properties. And both HP and Desktop Metal (among others) are developing binder jetting processes that can potentially produce production metal printed parts much faster than DMLS.
- What are the benefits and challenges of each?
DMLS is capable of very complex metal parts. One benefit is it can take out unnecessary material to make parts extremely light weight, or add functionality to a single piece such as a complex manufacturing fixture. The challenge of the DMLS process is the extreme internal stresses that can develop in parts during the build, so DMLS has among the most stringent design restraints of any 3D printing processes. Poorly designed parts can require a tremendous amount of support structures and will face dimensional issues.
The HP Multi Jet Fusion 3D printer has proven to be able to print nylon parts very quickly and with a consistent surface finish. The minimum feature size and layers are both slightly smaller than conventional SLS. Since there is no real support structure, the technology allows tremendous design freedom. However, MJF is still a relatively new technology with few material options. It is a strong option for low volume production, but due to the labor and raw material costs it still cannot compete with conventional manufacturing for moldable geometries at elevated quantities.
- How can users achieve better end-use production?
In general, production 3D printed parts should fit three needs: be highly complex in design, have a high value, with a need for fewer than 1,000 or so production runs. Otherwise, the parts may be better candidates for conventional manufacturing.
If the part is metal and needs to be DMLS, it is likely worth it to spend some time evaluating the geometry to see if it can be optimized for the process.
Virtually all 3D-printing processes benefit from having consistent wall thicknesses and adding internal and external radii to corners and edges. If the parts require secondary processes like machining or painting, keep in mind the parts will likely need to be fixtured and held somewhere, and think critically about what is really required. Do you really need a polished finish over the whole part, or just the aesthetic side? Does the whole part need secondary machining, or just a few holes reamed to spec? Cutting down on unnecessary requirements will keep costs and lead times reasonable.
These are just a few developments and features to keep in mind as additive continues to shift from a prototyping tool to a production technology. Stay tuned!