An Intro to 3D Printed Support Structure
It's one of our most frequently asked questions with new Metal AM customers.
"What is 3D Printed support structure?"
"3D Printed Support Structure" is sacrificial structure used when printing over-hanging features. It's primary purpose is to support design elements that would otherwise droop or sag. Much like construction scaffolding, support structure is used during building, and removed later.
This Scorpion build is a nice visual example; without support structure this build would have failed. After the build is completed the support structure is removed, leaving the original design.
Laying the Foundation
When the topic of 3D Printed Support comes up with new Metal AM customers, we cover 3 simple concepts:
Why we need printed support structure.
The "45 Degree Rule"
How a different approach to CAD design can sometimes avoid 3D Printed supports all together
Once this foundation is laid, we can have a much more meaningful conversations about Metal AM. We've gotten good feedback about this approach from our customers so we decided to share these concepts with the public.
Why do we use printed support?
Support structure prevents features from caving in or drooping.
The additive manufacturing process builds parts layer-by-layer (you can see a video of the process here) and it's impossible to "Print" a layer on top of nothing. For a build to be successful the design must "support itself", or printed support structure must deployed to support the overhang.
A simple example that illustrates this concept is a Mushroom vs. a Martini glass.
To successfully 3D print a Mushroom, the "Cap" requires support structure. The base/stem will print fine, but the cap will cave-in and droop since there's nothing underneath it.
The Martini glass will print well with no support at all. Each layer gradually steps out, making the structure "self supporting". It follows the 45° rule, which leads us to the next important concept.
The 45° Rule
An effective designer In general, it is good practice to keep over hangs above 45°.
We can push the limits of overhangs as low as 30° (depending on geometry, material, and machine parameters) but it increases risk of failure.
Features that are less than 45° from the build plate must be supported.
Self Supporting Structures
Here are a few examples of completely "self supporting" structures.
By eliminating support structure via informed and intelligent design decisions, the cost of the part comes down because a substantial amount of post-processing is eliminated.
Sometimes a CAD design simply cannot be changed to self support. In some instances, we can manipulate build orientation to minimize support, like in this heat exchanger example.
This Heat Exchanger would not print successfully if the design were "sitting flat" on the build plate. By tilting the entire part by 45°, all of the features are now self supporting. This particular component was selected for the cover of Metal 3D Printing Magazine.