MakerBot Tough PLA is an amazing material that combines the low cost and ease-of-use that regular PLA offers with strength that is similar to (or in some situations better than) ABS. In this blog, we investigate one of those surprising situations by exploring Tough PLA and printed living hinges and cantilever snap fits.

What is Tough PLA?

For those of you who are new to MakerBots, Tough PLA is filament that allows you to print durable, high-impact strength prototypes and fixtures. It is currently available for the 5^th generation MakerBot Replicator+ and MakerBot Replicator Z18, and it is purchased as a bundle with the Tough PLA Smart Extruder+.

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Design

Before we dive into the printing process, let’s start by going over some “design with 3D printing in mind” techniques. As you can see in the following screenshots (all of which are in millimeters), we’ve designed our snap fit cantilever arm and hook to be a bit more pronounced than one would normally be designed. In addition, our hinge is a bit wider than we would normally make this feature and has larger radii on the curve. Keep in mind that we want the outside contour of the hinge to be flat. As a result, we will be able to get a strong cantilever that is 4 contours wide, as well as a durable hinge that is approximately 2 contours wide.

MakerBot Print (Pre-Processing)

Setting the parts up correctly in MakerBot Print is one of the most important things to keep in mind when printing living hinges and cantilever arms. Setting the parts up vertically on their side allows us to give these features optimal strength, as our contours will form horizontally through the entire length of each feature. Essentially, we’re looking for the grain of the part to form parallel with are features, not perpendicular with them, as to avoid weak points that are prone to breaking easily. 

Our print parameters can change a fair amount, but for our sample part we used the .1mm layer height, 2 shells, supports, rafts and 100% infill to ensure good overall part strength.

Material Fatigue

In order to test how the Tough PLA material holds up when being used for living hinges and cantilever snap fits, we simply opened and closed the lid to our sample box 100, 200, 300 and 400 times, making sure to open and close the lid to the fullest it was capable of moving (approximately 260^O of motion).

*Click the images below to enlarge for more detail.

While we did experience fatigue in the material along the hinge over time, our snap fits worked perfect without any damage and our hinges never completely failed. Most thermoplastics, including regular PLA, ABS, PC-ABS, and PC, are too brittle for this application and can’t be compressed and stretched like this. As a result, Tough PLA joins nylon as one of the few materials durable enough to be used for prototyping living hinges and snap fits.

Download our infographic to compare other 3D printing material’s strength, toughness, heat deflection temperature and technologies best suited for specific industries and applications.