3d Printing Lattice

[Gaetan Boren]

3Dprinting is known for its lightweight parts and strength. Lattice structures in 3D printing are used to create lightweight designs with intricate repeating geometric patterns as support structures. Lattices can be printed as internal support structures or standalone components. These structures can also be used to increase the surface area of an object for improved adhesion and added strength. These complex geometric support structures are only possible in 3D printing processes.

A lattice structure is a 3D-printed support structure with an internal composition of several interlocked lattice nodes, also referred to as "cells." This structure is often used to make parts lighter and absorb impact more efficiently. The geometric design provides strength and rigidity in 3D printed objects while minimizing the amount of material and time needed to manufacture them.

The concept is based on natural designs such as honeycombs, spiderwebs, lobster shells, and silica sponges. Machining these geometries was impossible on a small scale. The only viable examples that can be achieved are massive construction projects, such as bridges and steel buildings.

In the 3D printing industry, understanding how to use and create these structures is quite valuable for product engineers and industrial designers. Lattice structures significantly reduce a part's mass and have countless applications in the automotive and aerospace industries, where mass reduction in parts directly translates to improved fuel efficiency. Other sectors where lattice structures are often used include medical implants, prosthetics, and other applications where weight, strength, flexibility, and complex geometry are important considerations.

Generative design is another method for generating 3D-printed lattice structures. The software requires detailed part information, including the expected loads, mass limitations, and connection points. The software generates the most optimal lattice design, as well as cell structure and density. Factors affecting the part design include the lattice material, construction, and cell orientation. The materials may consist of a hard shell with a flexible interior lattice for impact absorption. The structure of repeating uniform patterns and cell shape substantially affect the final product. Cell orientation can complicate a 3D printing operation. Ensure that cells are oriented without requirements for additional support.

The lattice structures used in 3D printing include the numerous benefits mentioned above that significantly impact fuel savings, product costs, performance characteristics, consumer appeal, efficiency, and sustainability. With software that can quickly design these complex structures and given these numerous advantages, it is apparent that incorporating lattice structures is definitely worth the added effort in design.

Looking for some insight or solutions for 3D lattice structures for 3D printing. We are involved in footwear and looking to expand our knowledge base on 3D printed lattice structures. We have had moderate success using nTopology, but it is not really ideal for all design applications.

The way I would go about it is this:

Figure out the cell structure that creates the lattice that I want.

Intersect the cell structure with the bounding shape to get the intersection curves

Pipe the intersection curves and the inner cell boundaries.

Done.

Has anyone tried printing lattices on form2 without support? Do you have problems with platform adhesion? Or, are there certain settings you recommend?

In particular I am interested in printing with flexible resin.

thanks a lot!

If you put your own raft (a 1-2mm layer) at the bottom of your lattice, you should be able to print that directly on the build platform in Flexible, with no added supports. You might also be able to print some lattices directly on the build platform with no raft and no supports, but it would depend more on the shape and scale of the lattice than the lattice-attached-to-a-raft version.

I have a UM3 and lately I've been printing components that consist of a tubular shell with a small period lattice structure inside of it. I've been running into a couple problems with them. As these components are for my work I cannot share the file but I have small sections of the current print below that should illustrate my problems. As these are multiple day prints I hope to fix these problems before the next iteration of the component without much more trial and error.

For one, the shell itself contains layers that did not seem to print. After running through the setting descriptions, it sounds to me like the fix for this not checking the 'Ignore Small Z Gaps'. From what the picture shows, does this seem like the correct course of action?

The other issue is that on the periodic layers where the lattice converges on itself resulting in many discontinuous vertices (the layer in the picture), there seems to be an extremely high degree of filament looping (not sure on nomenclature there) and vertical stringing. I think part of the problem could be that I have exceeded the Maximum Retraction Count threshold so the extruder lifts and moves to the next vertex without retracting the filament after a certain number of vertices have been printed. But even when it is under that threshold and it is clearly retracting the filament, I'm getting a lot of thin upward stringing still. So if my assumptions are correct I guess my questions are 1) how far can I push the Maximum Retraction Count threshold without grinding up the filament? and 2) how do I reduce that stringing in general? (I've seen the Ultimaker/Cura guide on reducing stringing but some of it seems outdated for the UM3. What are the UM3 setting thresholds that can reduce it?).

So I have thoroughly gone through the X-ray and layer view (single layer at a time) and have seen absolutely no gaps in the layers or other errors. You said you recommend disabling all mesh fix options? Even the ones that seem irrelevant to this scenario?

The two pictures below are representative of the extremes in the lattice geometry; straight parallel sections and crossed sections. The crossed sections are where the looping problem is obviously but it is unclear if there is a correlation to the issue with the outer shell at these layers as well.

The tube diameter is 2 inches and wall thickness is 1.25mm. The lattice XY wall thickness is hard to say because it morphs as it goes up the z direction but it is very thin in the straight parallel sections. There are clear holes in the lattice wall but those I am less concerned about those since we perform an epoxy process on the parts after to seal holes.

Several softwares are used including Solidthinking-Evolve, Blender, and Materialise-Magics. The STL goes through polygon fixing process in Magics to fix bad edges and noise shells, overlaps and intersections.

Or does the fact that the wall thickness is not a multiple of the line width perhaps cause problems? I wouldn't think so because its only on some layers and not others but perhaps the lattice converges at certain points on the wall and changes the effective wall thickness?

Our helpful design aid demonstrates part features that are too thin or too thick, bad bosses, right and wrong ribs, and other considerations to be mindful of while designing parts for injection molding.

Additive manufacturing (3D printing) is unique in its ability to produce parts with lattice or mesh structures. These lattices are a versatile tool for engineers for several reasons. Lattice structures help make parts lighter and stronger. They can also help reduce part volume, which leads to fewer surface defects and prevents excessive stress buildup. Less volume has the added benefit of saving on build time, and therefore cost. The additional surface area of lattice structures can also be used in heat transfer applications. Read on to learn how to use lattice structures in your 3D-printed parts without making a mesh of things!

Stereolithography (SLA) and Carbon DLS are resin-based technologies that require supports when printing. For these technologies, we prefer having a few drain holes to allow us to rinse the uncured resin out of the part prior to the UV post-cure. If any uncured resin remains, it will solidify during the post cure process. If the lattice needs to be completely enclosed, we can add drain holes for the build and part cleaning, and then plug the holes before shipping. You can use the Special Instructions field in your quote to request that we add drain holes and plugs and let us know if you have a preferred location for these features.

Direct metal laser sintering (DMLS) is a powder-based technology for metal that also requires support structures. Unlike our powder-based plastics, the metal powder is not caked onto the parts. The powder flows freely, like sand, making it much easier to clean out internal cavities. We also have a powder-removal machine that shakes and vibrates parts to get powder out of complex internal channels. However, any powder that remains inside the part will solidify during the stress relief cycle. If a channel or cavity needs to be clear, make sure there are plenty of places for powder to drain.

Selective laser sintering (SLS) and Multi Jet Fusion (MJF) use powder-based plastic materials. Both rely on partially sintered or partially fused powder to support the parts during the build, removing the need for additional support structures. This means that the powder surrounding the parts is caked on like dried mud. We use compressed air to remove the powder after the build. However, we require a direct line of sight to the powder to effectively clear it out. While the air will eddy around the inside of the cavity, only the powder directly in front of the air nozzle will be removed. Because of this, lattice structures for SLS and MJF should be designed with plenty of access points for clearing powder.

Below are examples of parts with increasing access to clean out the partially sintered/fused powder. The first example, on the far left, allows very little powder to be removed. Powder will be cleared in the area around the opening, but far corners of the part will be filled with powder. The middle example is better, there is significantly more access to blow out the powder. However, some powder may remain in the very back of the part in areas that are the hardest to reach. The last example, on the right, is ideal; there is plenty of access to remove powder and we can approach powder removal from both sides.

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