3D printing, an innovative manufacturing process, builds parts layer upon layer, necessitating a foundational layer for subsequent construction. Depending on the 3D printing technology employed and the geometric complexity of the design, support structures may become indispensable. These supports act as temporary scaffolding, ensuring successful fabrication of intricate designs.
When selecting a 3D printing method, understanding support structures is crucial. They significantly influence the final part quality, production cost, and surface aesthetics. Often, removing supports leaves behind blemishes or a rough texture, requiring post-processing.
This comprehensive guide elucidates the role of support structures in 3D printing. We will explore their implementation across various technologies and analyze how their use impacts technology selection for your project.
FDM 3D Printing Supports: How They Work
Fused Deposition Modeling (FDM), a widely used 3D printing technique, operates by extruding a thermoplastic filament onto a build platform, following a pre-defined path. As the molten material is deposited, it rapidly cools and solidifies, creating a solid layer upon which the next layer is built.
In FDM, each layer consists of extruded filament strands that bond to the layers below and adjacent strands. Each successive strand is slightly offset, allowing for the creation of angles up to 45 degrees without support. This method permits the construction of forms that extend beyond the dimensions of preceding layers.
However, when a design incorporates an overhang exceeding 45 degrees, the extruded material may sag excessively, potentially compromising the print integrity. In such scenarios, support structures become essential to provide the necessary base for these overhanging features.
When Are Supports Needed in FDM 3D Printing?
Consider 3D printing models of the letters Y, H, and T using FDM.
The letter Y, with its angled arms, can be readily printed without supports. These arms, although extended, do not exceed the critical 45-degree overhang angle.
The letter H presents a slightly more complex scenario. If the central bridge is shorter than 5mm, it can typically be printed without supports, minimizing any sagging. However, if the bridge surpasses 5mm, supports are necessary to prevent deformation. In the illustrated example, the H’s bridge is longer than 5mm, thus requiring support structures.
The letter T unequivocally necessitates supports for its horizontal top. These outstretched arms have no underlying structure to be printed upon, and without supports, the material would simply droop and fail.
The following image visually clarifies these examples, with support material depicted in light gray for illustrative purposes.
Here are the printed models, demonstrating the impact of supports. The second image highlights the failed T print due to the absence of supports, exhibiting significant sagging and necessitating extensive post-processing for rectification.
Bridging in FDM: An Exception to the Rule
An exception to the overhang rule in FDM 3D printing is the concept of bridging.
Heated filament can be effectively stretched across short spans between two anchor points during printing. This technique, known as bridging, allows for printing certain features without support material and minimizes sagging. For bridges exceeding 5mm, supports are generally recommended to maintain a high-quality surface finish.
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Disadvantages of FDM Support Structures
The potential requirement for support structures is a key consideration when evaluating FDM for a specific application. A primary limitation of FDM supports is the necessity for post-processing to remove them. This process often results in surface imperfections or roughness at the points of support contact.
Furthermore, layers printed on supports tend to be less uniform compared to those printed on solid layers of filament. This is because supports lack the stable foundation of solid layers. Removing supports, particularly from intricate details, can be challenging and carries the risk of damaging delicate features.
The inclusion of support structures also adds to the overall cost of FDM printing. Supports consume additional material, which is subsequently discarded, increasing material waste and requiring more operator time for removal. Increased material consumption and manual labor translate to higher production expenses.
Estimating Support Material for FDM Prints
The volume of support material needed for an FDM print is highly design-dependent. For instance, printing a replica of the Gateway Arch in St. Louis requires minimal, strategically placed supports to ensure accurate printing of its arch shape.
Conversely, a “ball in a cube” design necessitates a substantial amount of support material. Removing these supports is a complex and time-consuming process, often requiring needle-nose pliers to meticulously detach each support element while minimizing damage to surrounding surfaces. Sanding and smoothing the areas after support removal can also be challenging.
However, without these extensive support structures, printing such a model using FDM would be impossible without compromising part quality and dimensional accuracy. In this case, despite the added cost and print duration, the extra support material is crucial for realizing the design.
Types of Support Structures in FDM 3D Printing
FDM 3D printing primarily utilizes two main types of support structures. The most common type, suitable for a wide range of FDM parts, is the lattice or accordion support. The other type is tree-like support, characterized by minimal contact with the printed surface, often resulting in improved surface finishes post-processing. While less frequently used, tree supports are favored by some operators for specific applications.
The choice of support type is typically determined by the FDM printer operator, who selects the most appropriate option to optimize print success and minimize cosmetic impacts on the final part.
Dissolvable Supports for Enhanced FDM Printing
Advanced dual-extrusion FDM printers can utilize dissolvable support materials. These specialized materials are printed as supports and can be dissolved in a chemical solution after printing, leaving the primary part untouched.
Dissolvable supports offer superior surface finishes in areas where supports were in contact with the model. However, this method can be more expensive and time-consuming compared to traditional support removal.
Industrial-grade FDM machines are commonly equipped to handle dissolvable support materials. For example, the Ultimaker 3 is compatible with PVA (polyvinyl alcohol) support material, which readily dissolves in water after printing.
SLA & DLP 3D Printing: The Necessity of Supports
Stereolithography (SLA) and Digital Light Processing (DLP) 3D printing technologies fabricate objects from liquid photopolymer resin, using a light source to selectively solidify the material.
Depending on the printer configuration, two primary methods exist: bottom-up and top-down. Bottom-up printers lift the model from a resin vat, solidifying layers through a transparent window at the vat’s base. Top-down printers submerge the model into the resin as each layer is cured from above.
To ensure proper adhesion to the build platform and prevent parts from detaching and floating within the resin vat, SLA and DLP printing almost universally require support structures.
SLA and DLP supports are typically thin, rib-like structures with minimal contact points to the model. This design minimizes material usage and print time. Software algorithms calculate the optimal number, placement, contact points, and structure of supports based on the part’s geometry, orientation, and weight.
SLA and DLP are renowned for their high precision, capable of producing intricate and detailed parts. With proper post-processing techniques, using supports does not compromise the final part quality in these technologies.
Removing Support Material from SLA & DLP Prints
Post-processing for SLA and DLP typically begins with rinsing the printed part in Isopropyl Alcohol (IPA) to remove uncured liquid resin. Support structures can then be carefully broken away or removed using pliers. Any remaining marks at the support contact points are typically addressed by sanding to achieve a smooth surface finish.
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Material Jetting: Supports are Always Necessary
Material Jetting technologies, such as Stratasys PolyJet and 3D Systems MultiJet Modeling, operate similarly to inkjet printing. Instead of ink on paper, these printers jet layers of liquid photopolymer onto a build tray and instantly cure them using UV light.
Material jetting invariably necessitates support structures for any overhanging features, regardless of the overhang angle. Supports in material jetting are either water-soluble or removed through post-processing methods like pliers, water jetting, ultrasonic baths, and sandblasting.
Unlike FDM, supports in material jetting do not negatively impact the part’s aesthetics, surface quality, or mechanical properties. With proper post-processing, it is virtually impossible to discern where supports were attached.
Design Optimization for Material Jetting Supports
Post-processing for material jetting often involves powerful tools like waterjets and sandblasters. These tools, while effective, can potentially damage or distort delicate features. Adhering to Material Jetting design guidelines is recommended to mitigate such issues. For designs with highly intricate features or thin wires, SLS printing might be a more suitable alternative.
SLS 3D Printing: Support-Free Design Freedom
Selective Laser Sintering (SLS) 3D printers utilize a laser to fuse powdered material within a build chamber, layer by layer.
A significant advantage of SLS is that it does not require support structures. The surrounding powder bed acts as inherent support for the part during printing. This allows for greater design freedom, but generally increases the overall print cost and time. SLS requires a cool-down phase for the build chamber and a multi-step post-processing procedure to remove unfused powder, typically using compressed air.
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Binder Jetting: Powder Bed Support System
Binder jetting, similar to SLS, utilizes powdered material and builds parts layer by layer. However, instead of a laser, binder jetting employs a binding agent jetted from a nozzle to fuse powder particles together.
Like SLS, binder jetting eliminates the need for support structures. The surrounding powder bed provides support throughout the build process. Post-processing involves powder removal, typically with compressed air or similar methods, as well as other finishing steps.
Metal 3D Printing: Supports for Anchoring
Metal 3D printing technologies generally require support structures to anchor parts to the build plate during fabrication. However, overhangs angled at 35 degrees or less can often be printed without supports in metal 3D printing.
When supports are necessary for metal 3D printing, accessibility for removal is paramount. Difficult-to-reach supports can make post-processing challenging or even impossible.
Using supports in metal 3D printing does not compromise the final part quality. With appropriate post-processing techniques, all traces of support structures can be removed, leaving a clean surface finish.
Protolabs Network Tips for Optimizing 3D Printing with Supports
Whether or not your project necessitates supports, understanding best practices is essential for efficient 3D printing.
- Support structures generally impact surface finish. Post-processing is usually required to improve the surface quality after support removal, except for Material Jetting.
- Increased support structures expand design possibilities for certain technologies. Optimizing part orientation, accuracy, and other design and manufacturing parameters can minimize support material, reducing cost and print time.
3D Printing Technologies and Support Requirements: A Summary
The essential question remains: which technologies require supports? The table below summarizes support needs for various 3D printing technologies offered by Protolabs Network.
| 3D printing technology | Do I need support structures? |
|---|---|
| FDM (desktop & industrial) | Depends on model geometry |
| SLA & DLP | Always |
| Material Jetting | Always (dissolvable) |
| SLS & MJF | Never |
| Binder Jetting | Never |
| Metal 3D printing | Always |
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Frequently Asked Questions about 3D Printing Supports
Are supports always necessary in 3D printing?
If your design includes overhangs or bridges, and you are using technologies like FDM, supports are likely required. Consider technologies that minimize or eliminate supports or utilize dissolvable support materials for complex geometries.
Which 3D printing methods are support-free?
SLS, MJF (Multi Jet Fusion), and binder jetting 3D printing technologies inherently do not require supports. These are ideal choices for complex designs where support removal would be challenging.
What are common types of 3D printing supports?
Lattice supports are widely used and versatile, suitable for many 3D models. They are easy to generate and customize but can be challenging to remove and may leave surface marks.
Do supports increase 3D printing costs?
Yes, supports generally add to the overall cost. They consume extra material, extend print times, and often require manual removal, increasing labor and material waste. While specific costs vary, supports invariably contribute to a more expensive final part.
