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Support structures: Why they matter and how to design for them

When it comes to additive manufacturing (AM) support structures are a vital component to any build. Support structures are elements of a build that are made to properly support a part during the printing process to ensure a stable and successful print. Without them, prints are subject to failure.

There are many design elements to consider when building something additively, but designing with supports in mind is one of the most critical if you want your build to print as expected. By sticking to a few key guidelines, a designer can ensure that their part will be both accurate and repeatable. 

Support considerations across processes and materials

Not all processes are created equal. Some types of AM processes do not require support structures. MJF or SLS technologies are at an advantage because these processes involve layering within a powder bed. This powder serves as a support for the parts to res on, eliminating the need for additional support. Vat polymerization technologies, such as SLA or DLS, typically require supports. Engineers and designers can reduce the amount of support required by creating flat surfaces that can be directly adhered to the build plate or creating self supporting geometries. 

It's important to note the specific design requirements for each process. For example, Carbon® DLS has unique requirements in regards to the length of overhangs before supports are needed. Understanding the capabilities of specific machines and processes can greatly improve part quality. All additive technologies require a method of holding up parts and features as the build, so it's important to consider placement and quantity of supports. This can be dependent on a number of factors including part geometry, part orientation, and resin type. Generally, overhangs smaller than 2.0 mm and angles greater than 40 degrees horizontal do not require supports. 

Know what supports types are available

Supports can vary in design and type, but there are two specific categories that support structures typically fall into: trees and fences. Trees have a basic design that are characteristically long - similar to that of a tree branch - and can reach over longer distances to support a specific section of a part. Fences can be described as having a wall-like design with various types of mounting points that are usually at a 45 or 60 degree angle at the part touch-point.

These support types have unique capabilities and uses. Trees serve as a simple and rapid support mechanism. This is due to the fact that they can be quickly designed , applied, and tested. In some cases, the trees may also be implemented in the final build, particularly for rapid iteration or support of relatively small features. Fences are typically better choice for cosmetic pieces and high volume applications due to their durability and ease of removal.

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Design to improve part quality

While supports serve as an integral part of any additive build, the overall goal is to create a design that requires little to none at all. With the addition of support material, the cost, repeatability, and amount of waste incurred by a build suffer. This is due to the extra material and print time required to produce the part - all to build something that won’t be included in the final product. The post-processing required to remove support artifacts will also introduce variability. Because of this, parts should be designed in such a way that reduces the amount of supports needed.

There are a few elements that can be considered when designing to limit support structures. Incorporating chamfers, gussets, or radii into a design help reduce the total amount of support structures needed by making geometry self-supporting. From a client perspective, it's also important to specify areas in which support artifacts left on the part surface are acceptable. This can help reduce the cost of labor for post processing while also improving repeatability for the part.  

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Support structures will continue to play an integral role in additive manufacturing. While the end goal is to eliminate them entirely, manufacturing engineers can manipulate support design to optimize for part functionality and cost. To learn more about support structures and how to optimize your design for additive, contact the Fast Radius team today.