In 3D printing process, all parts are produced layer by layer. In reason of 3D technology specifics and 3D parts complexity, support structures are required. Once we consider which technology to apply, it is critical to consider support structures with final affection. Support structure will impact parts surface finishes, it requires post-processing to remove, this will result to blemishes or roughness on surface.
Support in FDM
With FDM printing, every layer is a heated filament, which adhere to other layers below and around it. We can build up the model with angle of 45 degrees by the way of slight offset with previous layer. Once we need to print a feature with an overhang beyond 45 degrees, we should add support materials to hold it up and avoid sagging.
YHT of FDM Support
We can consider the letter Y, H and T in FDM printing process.
- In Y letter, although it has outstretched arm, it can be printed easily. In reason of the arm angle is 45 degrees or less.
- In H letter, if the center bridge is under 5mm, it can be created without support structure or any sagging. However, support is required once over 5mm.
- In T letter, support structure is required for the arms. Without support structure, the melt materials will fall down.
Downside of FDM Support
- Support structure in FDM has a limitation of post-processing requirement. This will give rise to marks or damage on parts surface in support contact area.
- Another issue is that layers on support will be less perfect, because support structure is less stationary than the solid layers.
- Support is very difficult to remove from small and intricate features.
- Support requires additional printing materials, this will give rise to additional cost. In support removal process, post-processing will also increase total cost.
FDM Support Types
There are two common support types in FDM:
- The sort of flat accordion or lattice. This is the most common type, which is suitable for most FDM parts.
- The tree-like support. This method is less popular, which has less contact with parts surface. This will result to a better surface finish after post-processing.
We will select the best suitable support types for your specific applications, in order to minimize the impact on aesthetic appearance.
Support in SLA
SLA create 3D parts from liquid resins of photo-polymers, these resins are solidified by a light source. As different SLA printers, there are two typical producing methods. SLA parts can be pulled out from liquid materials vat by a light source at bottom, or submerged into liquid vat by a light source at top.
in order to adhere SLA parts to platform, SLA requires support structures at most cases. These support structures are thin ribs with small tips, which contact to parts surface. The support number, location, connection area are all calculated by software, normally affected by parts shape, orientation and weight. SLA is the most accurate technology, it can print intricate parts with accurate details, with proper post-processing, the support structure will not impact final parts quality.
Support design considerations
- Part orientation is a critical role in SLA support design, we can reduce the amount of support by part reorienting.
- If surface aesthetic appearance is paramount for SLA parts, we should also reorient parts to avoid support structure on required surface.
- For complex parts with thin or intricate features, we can divide parts into separate sections and assemble after printing, this will also improve parts quality and appearance.
Support in MJF
MJF is similar to inkjet printing, the liquid photo-polymer will be jet on build platform layer by layer, then solidified by a UV light system. In MJF design process, overhanging features always require support, regardless the angles. These support structures will never affect parts appearance, surface quality and technical properties.
Support in SLS
SLS process fuse powder materials by a laser system in a chamber. In this process, there is no need of support structures, the unsintered powder will play the role of support. This will increase the design freedom, but also increase the printing time and cost.
Support in Binder Jetting
Binder Jetting is similar to SLS, powder materials are bonded by binding agent layer by layer, and finally create the parts. In this process, support structure is not required, in reason of powder play the support role.
Support in DMLS
DMLS technology always requires support structures to fix 3D part on base plate in printing process. But overhangs over 35 degrees also can be produced without support.
In support usage, we should make the easy access of support, in order to guarantee that the support will not impact final part quality.
Support will impact the appearance of parts, post-processing is required to improve surface finish. More support structure will increase design complexity, the support also need to be optimized by orientation and accuracy, in order to reduce cost and time. We summarize the support requirement in 3D printing as following:
|3D Printing Technology||Support Requirement|
|FDM||Depended on part geometry|