3D Print Material Preference

Posted: August 21, 2021 in 3D printing, Uncategorized

PC/ABS is a blended material that combines Polycarbonate with ABS. The resulting material is stiffer and stronger overall than ABS alone. It is also tolerant of higher heat application than ABS. It glues well using structural adhesives and solvent bonding. While somewhat better than ABS for UV tolerance, the difference is small. PC/ABS main advantage is its rigidity. It also takes paint as well as ABS, with similar preparation processes. However, this comes at the cost of being harder surface, which makes sanding and secondary finishing more difficult. Further, the layer to layer bond of PC/ABS is not quite as good as ABS, which is aggravated by its stiffness overall, so layer separation and cracking can be an issue, that requires design consideration. PC/ABS is also not tolerant of stretching around threaded connections, so greater tolerance needs to be allowed to keep screws from breaking out of bosses.

A significant disadvantage of PC/ABS is that printed parts are very tightly bonded to the support materials. This means breaking away supports is generally not possible, and the bond between the support and the build tray is higher. The end result is a lot of support material has to be removed in the soak tank to dissolve it, which means regular and frequent changes in tank solution – and related disposal.

ASA Acrylonitrile Styrene Acrylate is a relatively new plastic that is used regularly in the auto industry. It has similar properties to ABS, with a few important exceptions. The layer to layer bond of 3D printed ASA components is superior to the other two materials, which makes thin wall sections tougher. The high level of acrylics in its composition also produces the highest bond strength when using solvents, acrylic bonding adhesives, and polymer adhesives. ASA is also slightly more flexible, which means it takes screw fasteners readily, and tends to bend before breaking, so in application is tougher. In application. ASA is also highly UV resistant, as the Butadiene Rubber has been replaced with Acrylate. Surface finish quality from FDM printers is superior to the other two materials. Since ASA is somewhat softer, it is the easiest of the three to sand and paint, and accepts paint very well. Heat tolerance is similar to ABS. However, the disadvantage of ASA is it is more flexible. This requires design consideration, as it may not provide the stiffness required for rigid assemblies unless wall thickness is increased or structural details are added.

Another key advantage of ASA in 3D printing, is that it does not bond as solidly to the support materials when printing. This means breaking away support structures is readily employed, avoiding the wet material removal tank process in many cases. Being able to break the bulk of support structures away also means the material remove solution in the soak tank lasts far longer.

Other Choices include ABS/CF, with is carbon fiber reinforced ABS, Nylon, and PLA. PLA is cheapest of them all, but is the most brittle and difficult to glue and finish well. Nylon is very strong, but is not as strong in layer bonds, and more difficult to glue and finish. ABS/CF has a place in structural single component elements, and will provide stiff parts, but with no improvement in finishing, and more issues with cracking.

For the Lighted Objects I Create

I use two materials most often. PC/ABS was once my go-to material. Over time, I have migrated to ASA as the primary choice due to its easy of adhesion, high layer bond strength, ease of surface sanding, and flexibility over brittleness, that means fewer cracked parts when screws are used as assembly fasteners. The lower print head temperature and reduced bond to the support material are also key benefits, making post processing much simpler and more efficient.

Spec Comparison of Materials Used

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