Need a part that bends, squeezes or absorbs shocks? TPU (thermoplastic polyurethane) is the go-to material for flexible 3D printed parts. It is used for gaskets, grips, bumpers, phone cases, seals and shoe soles. This guide explains how TPU behaves, which process to choose and how to design flexible parts that work.
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What is TPU?
TPU is a rubber-like plastic that stretches and returns to its shape. Its softness is measured on the Shore A scale: the lower the number, the softer the part. Common 3D printing grades range from about 85A (soft, like a rubber band) to 95A–98A (firmer, like a skateboard wheel or shoe sole).
Key properties
- Flexible and elastic: bends and stretches many times without breaking.
- Abrasion resistant: handles rubbing and wear well.
- Shock absorbing: great for bumpers, feet and protective parts.
- Good resistance to oils, greases and many chemicals.
FDM TPU vs powder TPU (SLS and MJF)
| FDM TPU | SLS / MJF TPU | |
|---|---|---|
| Cost | Lower | Higher |
| Complex shapes and lattices | Limited | Excellent, no supports needed |
| Strength in all directions | Weaker between layers | More even |
| Surface | Visible layer lines | Matte, slightly grainy |
| Best for | Simple gaskets, bumpers, sleeves | Lattices, cushioning, complex seals, wearables |
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Design tips for flexible parts
- Control flexibility with thickness. The same TPU feels much softer in a 1 mm wall than in a 4 mm wall. Thin walls flex, thick walls feel stiff.
- Use lattices for cushioning. Lattice structures (best in SLS or MJF) let you tune softness without changing material.
- Keep walls at least 1 mm thick so the part does not tear.
- Avoid sharp inside corners. Round them so the part does not tear when it bends.
- Allow for stretch in seals. Size gaskets slightly smaller than the groove so they compress and seal.
- Do not rely on tight tolerances. Flexible parts deform when measured, so design functional fits with some give.
Common applications
- Gaskets, seals and O-ring alternatives
- Grips, handles and soft-touch covers
- Bumpers, feet and vibration dampers
- Protective cases and sleeves
- Cable strain reliefs
- Prototype shoe soles and wearable parts
Frequently asked questions
Is TPU the same as rubber?
No. TPU behaves like rubber in many ways, but it is a thermoplastic. It is not as heat resistant as silicone rubber, and it can be printed, melted and recycled.
How soft can 3D printed TPU be?
Typical grades go down to about 85A. For softer feel, use thinner walls or a lattice structure.
Can TPU be used for watertight seals?
Yes, with enough wall thickness and a design that compresses the seal. Test a sample under real conditions first.
Learn about other materials in our filament comparison and PA12 nylon guide, or get an instant quote for TPU parts.
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