Unfortunately, not all 3D models are suitable for 3D printing. Whereas for virtual applications, for example, if the 3D model is visually impressive, certain criteria must be met for 3D printing. It goes without saying that form and (in the case of color 3D printing ) color are defined, but there are also other criteria that are crucial. For example, it is also important for 3D printing that the orientation of the surfaces (‘normal’) is clearly defined. We have compiled the most important design criteria for you:
Connection of edges
Two adjacent surfaces do not necessarily form a gridline network. For your 3D models, make sure that edges are fully connected to each other so that they form a ‘shared’ mesh grid instead of two separate ones. One can easily visualize this by moving a corner – it is a closed edge, moving both surfaces, in the case of non-connected edges moves only one surface (see figure).
Closed volume – ‘waterproof’
Only volumes can be printed, not individual surfaces (ie a certain wall thickness must be deposited). Extrude surfaces in your 3D model or combine several surfaces into a solid. This must be completely closed, ie there must be no holes (ie missing polygons). The latter can happen ‘accidentally’ in some programs in some operations, such as Boolean operations.
The orientation of the surfaces is also important, for example, if a single surface in the mesh grid has a wrong orientation (‘normal’), this has the same effect as a gap.
In most 3D programs, the inside and outside are color-coded, eg in Blender (depending on the settings) the outside is gray and the inside dark blue. With Blender, you can check if your model is waterproof by simply using the ‘Solid Check’ tool in the 3D Printing Toolbox.
Each edge can only connect two surfaces. Imagine that you have two cubes of the same size and move them so that they are directly edge to edge. If edges are separated, they are two separate solids. However, if it were one and the same edge, the edge would connect 4 surfaces. Such a construct would not be printable and therefore must be avoided.
Operations such as scaling the 3D model or technologies such as 3D scans can sometimes lead to the formation of redundant volumes (called second-order shells).
These are partly, useless’ structures that are often free in space and cause no obvious damage. However, such structures may well jeopardize the 3D printing process. For example, creating an additional structure within a cavity can close openings through which material is to be recovered (‘escape holes’) – which often leads to a significant increase in costs. You can also learn Performing the Modal Analysis and Harmonic Analysis in Ansys training center in Coimbatore.
In addition, superfluous structures can merge with other models or structures of the actual model during printing and thus render the model unusable. Best practice is therefore
If triangles cross each other, this can lead to difficulties in some printing processes. Although this usually causes no problems with the powder printing process, it can lead to complications in FDM. It is best to completely avoid polygon collisions in 3D design. Unfortunately, collisions occur frequently in some 3D scan procedures and must be manually corrected if in doubt.
If there are several triangles in the same place in your 3D model, we are talking about overlapping polygons. In the case of the SLA method in particular, this can lead to impairments, since corresponding points are exposed several times, which are often seen in the finished print.
If you have any questions or are unsure if your model is ok, just upload it, we will gladly give you advice on what needs to be improved on the model or if you wish, you can also do it for you.
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