What should you consider when creating a CAD file for a 3D Printing service?
Gaining an understanding of what is required when creating CAD for additive manufacturing can be slightly bewildering to begin with, but is easily obtained with a little experience. Firstly, deciding whether your part is going to be a multi-material or a multi-coloured piece is a crucial step. We have the capacity to print flexible prototypes in various ShoreA hardness with our Stratasys Polyjet technology, we can also produce highly detailed, fully functional parts with our EOS SLS 3D Printer as well as high performance true thermoplastic FDM printing and highly detailed SLA. For the best results send us your file with the performance requirements so we can review and guide you to the best option. But to begin with, once you have decided on your desired properties, you can consider the following points below.
- It is worth considering that all technologies have some sort of support removal which needs viable access to be removed. All 3D printing technologies have this inconvenient but necessary obstacle – easily worked around with proper design and process planning.
- Enclosed space may not be an issue if they stay enclosed (Support material will stay contained). However, areas with restricted access may leave support material remaining which can cause concerns of its own, like swelling or warping.
- Each technology has its own boundaries so this must be taken into account when deciding properties and process – although, parts can be digitally split and re-joined post-print in many instances.
Avoid thin walls and consider feature size
- If you part is scaled to fit your chosen technology thin-wall sections in your CAD must be reviewed to ensure they are printable and will not break during the clean-up process or under light handling.
- It may be worth considering a multi-technology option to gain the best of each – high resolution for the small parts, strong and lower costs for the very large parts.
- FDM feature size and wall thickness will vary depending on your part geometry, resolution and material selection. Generally speaking, the FDM 3D printed part wall thickness must be minimum of 0.45-0.85mm. For engraving details, embossing or other surface features a 1mm minimum is a good place to aim for.
- Polyjet parts can have a wall thickness of 0.6mm for rigid materials (0.8 for ABS-like) and 1mm for flexible materials. As a finer resolution 3d printing technology surface features are still viable at 0.4mm.
- SLS 3D printing has a minimum wall thickness of 0.8mm. Parts can be produced lower than this but the surface must run through the X/Y plane.
- SLA ideally needs a minimum wall thickness of 0.6mm for unsupported walls or 0.4mm for supported. Minimum hole diameter is 0.5mm likewise for engraving details, however, embossed details should be 1mm
Assemblies, fits and tolerances
- As a rule of thumb, if you want to join parts post-printing they are given a clearance of 0.6mm – this allows plenty of room for adhesive.
- For moving features on parts printed as an assembly this can be taken down to 0.5mm in your CAD file – anything below this will fuse together (Other than Polyjet which can be taken down to 0.15 on some geometries).
Split CAD/STL files for Colour or multi-material parts
- For multi material parts, a single STL or CAD file must be produced for each material type or variation (It is very helpful to label the material in the file name) all with the same world orientation. This allows us to import all components together to produce you part in one build. (Frog CAD images above for example)
So, there’s a few pointers to get you started, but IPF do have over 14 year’s experience in 3D printing with top manufacturing brands FDM, SLS, Polyjet, and SLA systems that has given us a wealth of knowledge. Orientating your design in the correct way in your CAD file can give you a superior part with longer lasting durability, great definition, vibrant colours and a smooth surface finish.
So if in doubt; contact us – we can help guide you through your design process!
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