EVERYTHING TO KNOW ABOUT- BRIDGING AND SUPPORT STRUCTURES

What is Bridging?

Is it possible to print a hanging Bridge without using supports? Yes, but you need Bridging for that.

Bridging is a process that extrudes material in a way that connects two points without needing any support structure.

You can get away with Bridging (without supports) while using shorter bridges but for larger prints/bridges, you need supports.

The material is extruded across the gap in two points to be bridged. It is later cooled to create a firm surface.

The 3D printer should be accurately calibrated ensuring suitable settings for special segments to get the best bridging results.

If you notice sagging, drooping, or gaps between the extruded segments, you may need to adjust your settings for the best results.

1. Increase Cooling: –

Increasing print cooling i.e. print fan speed, helps in optimizing the printer’s bridging capabilities.

Printing with low print cooling can lead the filament to sink into a big mess of molten plastic.

Too high fan speed can result in clogging or poor layer adhesion.

2. Decrease Flow Rate: –

Setting material quickly would ensure- bridging a gap cleanly.

A high flow rate means more filament flowing out of the nozzle.

Too much-molten filament releasing from the nozzle will not let the material to set properly.

This will result in drooping of the bridge.

3. Decrease Temperature: –

High nozzle temperature increases the flow of filament through the nozzle. This will not let the material to cool and set.

The result will be a messy bridge formation or the deposition of extra filament at the end of the nozzle.

Try testing different temperatures by manipulating the g-code to vary temperatures at each level.

4. Decrease Print Speed: –

High print speed affects the bridge quality as well.

A nozzle moving too fast will not leave enough time for the filament to adhere to the previous layer.

A nozzle moving too slow may lead the filament to be suspended in the air for too long and an eventual drooping.

5. Model Orientation: –

6. Supports Can be Helpful!!

Supports will eliminate all worries about messy, drooping or sagging bridges.

Just be sure that you will be able to remove supports after printing as one needs to be careful while removing supports.

Support structures provide an extra foundation for the bridging regions. They greatly improve the chances of success at 3D printing.

Despite all the wonders 3D printing could do, it still can’t overrule gravity.

Complex printing designs like overhangs, holes, and bridges are challenging to print due to gravity.

Supports are used for preventing distortion and collapsing of material while 3D printing these complex design features.

Support structures are not part of the 3D print model but are temporary add-ons to provide printing support to print such complex designs.

They secure parts to the printing bed and main body of the print.

Supports also aid as heat dissipaters in processes where high temperatures are involved, as is the case with metal 3D printing.

Not all 3D printing models require supports. Below are a few quick tips and tricks to know whether your particular model require supports or not: –

1. Overhangsor bridges: –

• Overhangs are places where the printer would have to print partially or completely over the air, such as the arms of the letter T or Y printed vertically.
• Bridges are overhangs that are connected to the model on both ends, such as the middle of the letter H. These are typically measured by angle, measured from the Z-axis above the overhang.
• For example, the letter T contains a 90-degree overhang, while the letter Y has a 45-degree overhang. 
• If you spot severe overhangs in your model (above 60 degrees), you probably need supports.
• And if your model has overhangs of over 90 degrees (eg. a lowercase r), supports are necessary.

2. 3D printer: –

• Not all 3D printers work best with different printer models.
• Try printing an overhang test to see how well your printer does. 
• If a 60-degree overhang doesn’t look so good, you should put supports on models with similar overhangs.

3. Print speed: –

• Generally, slower print speeds lead to higher quality prints.
• But when it comes to 3D printing supports, that’s not always the case.
• The faster the print speed, the better overhangs and especially bridges turn out.
• If you tend to print slowly, make sure to turn supports on.

1. Lattice supports: –

• These are the most common types of supports.
• Lattice supports are easy to customize, quick to generate, and work well for most 3D models.
• The one disadvantage is that in case of improper printing, supports leave marks on the finished model and become difficult to be removed.
• Lattice supports are used for flat, angular, or very steep overhangs.
• Make sure to pick a support pattern that fits your model’s shape. Some commonly used are concentric, lines, etc.
• Concentric is useful for spheres and other shapes that aren’t evenly supported by a grid.
• Lines make it easy to remove support, such as tricky holes or floors of a building.
• The other patterns are a little less commonly used, but feel free to experiment with them if the need arises.

2. Tree-type supports: –

• They start from a couple of ‘trunks’ near the base of your print, and branch out to support overhangs in your model as height increases.
• 3D printing these supports saves on material and print time.
• Tree-type supports are used for printing organic shapes (humans, animals) small or not very steep (less than 70 degrees).
• These supports sometimes take more time to generate but end up giving better surface finish.
• These supports do not work well for flatter overhangs, such as a roof, since they only touch the model at a few points.

3. Dissolvable supports: –

• Dissolvable filaments are essentially used to create support structures.
• It is non-toxic and biodegradable, making it the material of selection for many industrial applications, such as textile glazing, paper coating, and contact lens solutions.
• The best part about using it is that it cracks into harmless and non-toxic alcohol after it dissolves in water.

• Direct Energy Deposition(DED)

Direct Energy Deposition involves metal 3D printing technologies that work by melting and fusing material to create a part.

DED printing will always require support structures to ensure part stability, the printability of complex features, and for thermal dissipation.
 

• Design Of supports-
  When designing supports for such techniques, one should focus on ease of access. That way those supports can be removed easily post-printing.

 Supports for metal parts are usually designed as lattice structures.

They act as a heat sink, transferring heat away from the part, allowing it to cool in a more controlled manner and avoid distortion.
 
Adding more supports may result in more accuracy, but this will increase costs and post-processing time.
 

• Support removal-This is typically more difficult than polymer-based processes. Also, to maintain the appearance of the finished printed part, post-processing may be required after support removal.

·     Stereolithography (SLA)

This technology works by using a light source to solidify liquid resins.

It requires support structures to be securely attached to a part to the print bed to prevent warping.

The support structures used for SLA are wafer-thin.

They provide minimal support and are easily removable using hands or a plier.

Here also, to maintain the appearance of the finished printed part, post-processing may be required after support removal.

• Design Of supports-SLA is preferred for applications requiring smooth surface finish, such as visual prototypes, molds, and hearing aids.

 For this, it is important to make sure that no forward-facing areas of print are in contact with support structures.

·     Fused Deposition Modelling (FDM)

Parts are printed by extruding heated filament layer by layer. As each layer cools, it solidifies, bonding with the previous layer.
 

• Design of supports-
  If an FDM part has an overhang of more than 45° or involves features like bridges and protruding surfaces greater than 5mm, supports will be needed.

FDM supports can take the form of a lattice structure or a tree-like structure.
 

• Support removal-One of the common methods of support removal from FDM prints is a dissolvable solution.

Another preferable option is using support structures made with dissolvable filaments or PVA.

But one downside is that it can be affected by temperature changes, which can further lead to blockages in the printer head.

• Extra Material costs: –

Support printing will need additional material during the printing process, increasing both time and material costs.

Since supports are not reusable and have to be disposed of after the printing process some of the material is wasted.

• Extra time: –

Printing a part to accommodate support structures and subsequently designing the supports themselves takes extra time.

Although there are software offering automated support generation, creating support structures for industrial applications will still need some customization and some level of design expertise.

• Additional post-processing: –

To remove the supports after the completion of 3D printing, you need to be extra cautious. If not executed correctly, you might end up deforming the 3d printed part which would then require manual post-processing.

• Risk of damage: –

Removal of supports requires precision lacking which can affect the main 3D print model’s dimensional accuracy and aesthetics.

It’s usually better to minimize the number of supports needed as much as possible. To save on both material costs and production time, below are some measures that can prevent from using supports: –

1. Choose the optimal part orientation: –

• Choosing the right part orientation can have a significant impact on the printing time, costs, and a part’s surface roughness.
  Depending on a part’s orientation (vertical, horizontal, or angled), there may be fewer or more support structures needed.
• Consider a part printed in the shape of the letter T.
• In its ordinary position, both branches of the letter will collapse without support structures in place.
• If the part is oriented differently, i.e. ⊥, then supports will not be required.
• This example demonstrates that a part can be built up in different ways.
• Each side of a part can have a different surface attached to the print bed, meaning that the need for supports can vary and be heavily dependent on the orientation of the part.

2. Develop your support structures: –

• When supports cannot be avoided, they should be optimized to use as little material as possible and to speed up the printing process.
• For example, topology optimization can be used to design, supports with lattice structures, reducing the support volume of and saving material.
• With many 3D printing technologies, commonly used support printing techniques are limited to producing strictly vertical structures.
• Creating tree-like support structures instead may be a viable alternative.
• Such supports look like a branching tree and arguably consume 75 % less material compared to straight vertical structures.

3. Use fillets and chamfers: –

• Using fillets and chamfers can be an alternative solution to creating support structures for overhanging surfaces greater than 45 degrees.
• A chamfer is an angled corner or edge, and a fillet is more like a rounded corner or edge.
• Essentially, these features turn an angle that is greater than 45 degrees into an angle that is 45 degrees or less and can be added to either the interior or the exterior of a part.

4. Split your part: –

• For very complex 3D models, parts can be printed separately and assembled afterward.

This may reduce the number of supports and also speed up the printing process while saving material.

Read More : EVERYTHING TO KNOW ABOUT 3D PRINTING EXTRUDERS