Printing with TPU Flexible Filament: Shore Hardness and Which Parts It’s Ideal For

If you need a part that flexes in your hand, springs back when compressed, or grips a surface without slipping, you’ve reached the limits of rigid plastics. This is exactly where TPU flexible filament steps in. Belonging to the thermoplastic polyurethane family, this material carves out a unique place in the FDM world with its rubber-like behavior. In this article we’ll talk about TPU’s character, what Shore hardness actually means, and which parts it’s ideal for.

What exactly does Shore hardness measure?

On TPU spools you’ll often see values like 95A, 85A, or 60D. This is the Shore hardness scale, and it tells you how flexible the material is. In practical terms, think of it this way:

• Shore 95A: The most common starting point; roughly the firmness of a shoe sole, and the easiest group to print.
• Shore 85A: Noticeably softer and more elastic, but feeding becomes more sensitive.
• Shore 60–70A: Approaches a silicone feel, very flexible; requires a direct drive system.
• Shore D scale (e.g. 60D): Semi-rigid, impact-resistant parts that flex very little.

What should you watch out for when printing TPU?

Its flexibility also makes printing a bit more demanding. The soft filament can buckle and jam between the extruder gear and the nozzle. In general, slow and steady flow is the secret:

• Keep print speed low; aim for smooth, consistent flow rather than sudden speed changes.
• Reduce retraction distance — minimize it as much as possible.
• Direct drive extruders offer a clear advantage over Bowden setups.
• Keep the spool dry; moisture-absorbed TPU will bubble and crackle at the surface.

Which parts is it ideal for?

TPU shines in applications that require mechanical flexibility and grip. Phone and device cases, vibration-dampening mounts, gaskets, belts, wheel treads, grip surfaces, and impact-absorbing bumpers are at the top of the list. It also has reasonable resistance to abrasion and oils, making it worth considering for functional parts beyond the prototyping stage.

Choosing the right hardness

If your part needs to flex only slightly while holding its shape, 95A is usually the safest choice. If you want something genuinely soft and rubber-like, you’ll need to go down to 85A or lower — though in that case it’s important to print with a more controlled setup. If you’re unsure which hardness suits your project, the best approach is to share your part’s use-case with us and we’ll figure it out together.

If you need a flexible part, send your model through our quick order page and we’ll determine the right TPU hardness together.