3D Printing Support Structures

What is a Support Structure in 3D Printing? And Why Are Support Structures Important?

An FDM 3D printer extrudes filament layer by layer to form a 3D printed part. Each layer is supported by the layer beneath it. When a model has areas of a design that is not supported by a layer beneath it, such as with an overhang or a bridge structure, there is a risk the structure can fall. The amount an overhang can support itself depends on the stiffness of the material the part is made of. The stiffer the material, the further an overhang can stick out. However, even with a stiffer material, at a certain point, the weight of the overhang will overcome the stiffness of the material, causing the overhang to collapse. Support structures are a temporary added part that supports the areas of the part during printing. Support structures will need to be removed once printing is complete.

Simply put, when printing a new layer gravity will be dragging that layer down, meaning you can not print a new layer or structure (like a bridge or an overhang) over air. It needs support to hold it in place during the printing process. This why a support structure is needed. A support structure will ensure that new layers are not at a risk of falling.

When to Use Supports in 3D Printing

According to the 45-degree principle, any [section of a design that overhangs more than 45 degrees of off vertical] will require a support structure (at least a break away support structure).

Examples of Design Features That Require Support Structures (Reference actual printed examples)

1. When there is an overheard, the structure will need support.

2. The orientation of the model could result in the need of a support structure

 

The distinction between each support type and when to use it comes down more to the desired part qualities.

Desired part qualities include:

  1. Surface Finish
  2. Ease of Removal
  3. Time

If the design falls under 45 degrees, then it will not require a support structure.

Examples of Design Features That Do Not Require Support Structures

  1. When the overall shape is cylindrical, conical, or cuboid, and the lower part is relatively large
  2. When the upper and lower widths of the model are the same without any hanging parts

3. When the size/distance the part has to overhand is relatively short, the filament can bridge itself without the need of a support material underneath

Types of Support

Support structures can most likely fall into Break-Away or Water-Soluble types. Within these types are the following sub-categories inate supports, water soluble supports, and interface layers.

Inate Supports

Inate supports use the same material for the part and the support structure and it breaks away or a material pairs with a dedicated support material and the part made with the dedicated support material is broken away. Inate supports are easy to set up and have low print times, but can leave a rougher surface when the supports are removed.

 

A dual extruder 3D printer is not needed to produce inate supports done in one material, but producing these supports will be limited. Since these types of inate supports use the same material to support it, there needs to find a fine balance so the support structure can support the model well, but also remain loose enough to break off easily without cutting into the model.

 

 

However, with a dual extruder 3D printer, a dedicated support material would be used in a dual print and broken away like Inate supports.The PA12 support material for the E2CF is another example of a dedicated support material that can be produced with a dual extruder 3D printer. Dedicated support structures are rarely intended for part printing.

Water Soluble Supports

A water soluble support is a support structure made from a filament that dissolves in water, meaning they are the easiest to remove. Water Soluble supports provide the best surface finish because they do not need to be broken away meaning there is no risk of damaging the part when removing the supports. However, it requires more printing time to produce a water soluble support, as well as the soaking time to remove the supports.

 

A water soluble support may be needed in place of a regular support. Examples include complex tubing or where the tools can not reach the supports to remove them.

 

A water soluble support material for lower temperature is Raise3D’s PVA Plus (bed temperature of 60 C).

 

A water soluble support material for high temp materials is BASF BVOH (bed temperature of 100 C).

Interface Layers

Then the last category of support structures are interface layers. Interface layers are when inate supports are used for the main structure and water soluble structures are used for the layers that touch the part.

The main considerations for this use case is the final part surface quality and material costs. It does make it so that there can be some more work in removing the supports, if they surround the part for example, but since the layers between the parts and the main supports can be dissolved away to leave a gap there is much more room to work on the supports without the risk of effecting the part.

In this case we are also cutting down on the water souluble support material, which usually is more expensive, by only using it for the layers where it is needed most.

Different Support Materials

 

Main Material Support Material
PLA, TPU, PETG PVA
ABS HIPS
PA12CF PA12CF Support

 

 

ABS and HIPS (High Impact Polystyrene) are a common pairing since HIPS material prints at almost the exact same settings as ABS. HIPS can be dissolved and washed away with a chemical process, Limonene-D, which does not affect the ABS plastic. However there are restrictions on how Limonene-D can be used and disposed of. It is important to check with local ordinances for regulations of Limonene-D.

3D Printers

The right 3D printer needs to be able to maintain the right conditions to make the materials compatible. A machine with more accurate or fine-tuned motors will be better suited to maintain a proper material flow which is needed to facilitate proper bonding. A printer with motors that are not as efficient can impact the flow, which will ultimately impact bonding and make the material not compatible with the machine.