Design rules for 3D printing with Rigid Opaque Plastic
General Design guide lines
When you produce a 3D Model for 3D Printing, every surface must be joined to create a solid object that is watertight.
If you work with surfaces it is very important that all surfaces are joined, so there are no unclosed contours detected when the file is uploaded to print.
Saving files in STL format should be done at the highest possible resolution, the more polygons the better, as this will result in a smoother finish on your parts.
Parts saved in a low resolution will print! But the surface instead of being smooth will be made up of lots of flats to produce a curved surface.
If you have a file which is to big to send or upload, through our online ordering system, or normal email, please get in touch as we can discuss alternative methods of sending large files.
With PolyJet printing there are 2 types of finish! Gloss & Matt, If your parts have any overhangs, any material beneath the over hang will be a Matt finish, because all overhangs require support material.
Gloss: A gloss setting gives strength on thin walls, and a smooth finished part, it also reduces the material used.
Matt: A Matt setting will produce an accurate part, as well as the same finish all over, but extra material is required, and more post-processing to clean the part after printing.
Other design considerations are listed below which show the minimum sizes for each design feature!
If your design can not be printed through the automatic online order a 3D Print page button, it does not mean it can not be 3D Printed! It just means it will need a member of our team to check the file manually.
DESIGN OF POLYJET CASTING PATTERNS
With traditional patterns there are several design considerations to take into account, but depending on the volume of parts you require, will depend if you need to go for the more expensive metal molds or use 3D Print N Scan to produce a PolyJet pattern for you!
- Draft angles – to aid the release of parts – These are not required with a PolyJet pattern, as the part does not need to be removed from a mold, so you can have a part produced square as intended.
- Parting lines & wear and tear – Over time injection molding tooling will wear changing the geometry of your final part, eventually leading to new tooling being required, Parting lines are also visible on injection molded parts where post processing of each part is required, to remove the flashing created around the edge of the pattern, this does not occur with a PolyJet part! Because there is no tooling to wear and no tooling to create a split line.
- Complex geometry – The production and associated cost of complex geometry, and costly tooling in producing holes, pins, undercuts, bridges and spirals, the list goes on! Is no longer an issue with a PolyJet mold pattern! As the part does not need ejector pins, sliding gates, plugs, guides or inserts, with 3D Printing the part is printed how you want it to look at a fraction of the cost.
- When Producing a PolyJet pattern all our standard materials can be used, but the preferred material is Vero Black, this is because of its low ash content at 0.02% in comparison to our other materials at 0.3%, this material offers strength for the remaining processes after 3D Printing.
- When designing your parts good practices in the design are still required, so your part forms properly in the mold, and material can flow correctly.
- Knife edges should be avoided, and a 0.25mm fillet should be added to all edges.
- General fillets should be a minimum of 0.8mm radii.
- Wall thicknesses should be a minimum of 1.5mm.
- The part as a whole should be shelled out, so all features have a 1.5mm wall thickness, to allow the part to burn out and not expand and crack the ceramic mold.
- e.g. a 10mm wall should have a void of 7mm at its core.
- Parts should be designed, so they get printed without the use of support material inside the part, this will require the part to be shelled out to the minimum wall thickness, and split into 2 or more parts.
- Shrinkage of the final metal part should be accounted for in the design also.