The landscape of 3D printing is evolving rapidly, and these days, there are as many variables in 3D printing as dog breeds. If you’re new to rapid prototyping via 3D print, all the variables can leave your head spinning. During the learning curve, it’s easy to be swayed by aggressive sales staff, or wowed by the concept of the technology and end up getting parts that don’t match expectations.
Stereolithography or SLA:
SLA is the oldest and most evolved of all the processes. It offers the highest precision and best surface finish right off the tray. The parts are easy to clean, sandable, paintable and dimensionally very precise. However, the parts are not durable, will degrade over time, change size and shape over weeks-months, and become delicate.
Some modern resins are more durable and attempt to mimic production plastic qualities.
Most SLA machines produce amber colored resin parts.
You can specify a water clear resin, and some resins are more clear and less amber naturally.
Fuse Deposition Modeling or FDM:
FDM machines are affordable 3D printing machines that can be used in home or office environments, and are by far the most popular and prolific 3D printers.
Some FDM machines are high cost and produce parts that have higher resolution. The finished parts are actual plastic, but the parts will have a grain causing a weakness in the direction of the grain. They do not behave completely like injection molded plastic parts. FDM 3D printed parts can be printed in a variety of “off the shelf” colors, but cannot be color matched easily. The surface finish is rough and difficult to resolve. Even the higher resolution machines have a finish inferior to SLA. Coatings and paints often do not adhere well to the surface.
Sintering and Melting or processes or SLS
For simplification, we are lumping EBM, SLM, and all machines requiring no support structure as SLS in this article. SLS 3D printing machines have the broadest variation in styles, materials and capabilities. SLS produces parts that are more consistent structurally and have a better finish than FDM. This process offers a very wide range of build materials including low cost starch based materials, a variety of plastics, metals, and even titanium. Some machines can color match with use of pigments added during the build process. This category of machines can make just about anything.