How do you know what material is going to best fit your needs? That’s not an insignificant question, particularly if the item you’re printing is going to be responsible for any weight-bearing functions. How do you know if your filament will be strong enough? That’s a question that MatterHackers gets asked frequently. The retailer carries one of the largest selections of filament in the 3D printing industry, so their team knows a lot about filament and filament strength. After being asked again and again about what type of filament is the strongest, MatterHackers decided to do some testing to find out the answer.
“‘Strength’, however, is a bit vague as it can refer to a few different mechanical properties – tensile strength, yield strength, fatigue strength, compressive strength, and impact strength – so it’s a difficult question to answer without more information,” Taylor Landry from the MatterHackers team cautions. “…We’re not a testing lab and we can’t perform any scientific tests of those mechanical properties, and we surely didn’t find a Young’s Modulus. What we can do is perform a comparative test – putting 3D printed parts through the same test, and seeing how filaments compare to each other.”
To test different materials, MatterHackers decided to 3D print an object that better be as strong as possible: a carabiner. They scaled their model to approximately the same size as a typical aluminum carabiner you can find at the hardware store, rated for 150 lbs. They printed each test model on a Rostock Max with a 0.4mm nozzle at 0.25mm layer height and 50% triangle pattern infill, with five perimeters and five solid top and bottom layers.
The team then rigged up a force gauge to a block and tackle pulley system with a 8:1 ratio, meaning that for every one pound applied to one side of the system, eight pounds were applied to the other side. They tested each carabiner by attaching it to the pulley system and applying tension with a ratcheting cable until the carabiner failed. The force gauge recorded the peak force for each one. The results are as follows:
PLA, unsurprisingly, performed poorly, with PETG not faring much better. NylonX, however, was a welcome surprise, showing itself to be 100% stronger than PLA and 60% stronger than ABS on average. Polycarbonate also performed well, but was also the most challenging material to print with, requiring thorough drying before printing and having a tendency to warp.
“While we were applying tension to the 3D printed carabiners, we weren’t just measuring tensile strength. We found that the integrity of the latch and the ability of it to stay closed as long as possible was a huge factor in the max load before failure. The more flexible the filament is, the more easily the latch unseats/opens, and this leads to failure more quickly.”
Thus, while Taulman 645 performed poorly, that doesn’t mean it isn’t a strong filament – in fact, it essentially returned to its original shape after the weight was removed, rather than breaking. What MatterHackers’ test may have proved most of all is that strength is a complicated thing to gauge, and that what works best for one application might be completely wrong for another.