Helmond, The Netherlands, 13th of February 2020
When an objects is 3D printed with a transparent material one of the goals is to achieve a transparent object, but when printing with normal print settings the part will still look 3D printed and will not be completely transparent. Normally, when a fully transparent object is needed it will be made using injection moulding, but when using the two new Mitsubishi Chemical materials DURABIOTM and 3DIAKONTM a fully transparent object can also be made using 3D printing, see the pictures below.
To make a transparent 3D print using DURABIOTM or 3DIAKONTM some changes need to be made to the standard print settings to prevent gaps within the object which reduces the transparency. After printing the model it also needs to be post-processed via sanding and polishing to achieve a smooth and glossy surface.
Step 1: 3D printing
Some changes have to be made to the standard print settings otherwise the print will not become fully transparent. Use a small layer height (like 0.05mm, a 3D printer with a good automatic bed levelling is therefore recommended) and a slow printing speed (±25mm/s). To prevent the gaps between the individual layers and lines the material flow has to be increased by ±8% and the infill overlap percentage also needs to be increased a bit. To make sure that there are no gaps inside the model an infill of 100% needs to be used. The layers need to fuse together as much as possible so the cooling needs to be disabled. The print temperature for DURABIOTM needs to be increased (keep in mind the degradation temperature of 265ᵒC to prevent degradation of the material) and the print temperature for 3DIAKONTM should be kept at 260ᵒC.
Step 2: Post-processing – sanding
After the model has finished printing it can be sanded to create a smooth surface. Start with a grit size of 220 and finish with a grit size of 3000 using different increasing intermediate grit sizes. The following grit sizes are recommended: 220, 400, 600, 800, 1000, 1500, 2000, and 3000. If the print does not have a lot of details a grit size of 40 could also be used to speed up the process. It is also recommended to use wet sanding since this gives a better result and creates less mess than dry sanding.
Step 3: Post-processing – polishing
When the surface of the 3D print is completely smooth it is ready for polishing. This step requires a felt brush (suitable for a drill) and some polishing paste (which polishing paste works best could differ per material). Make sure that the print is clean and apply some polishing paste on the surface of the model. Next, insert the felt brush into the drill and let it rotate at a medium speed. Push the model against the felt brush and apply some pressure onto it. Rotate the model to make sure that every part of the surface gets polished.