Elastomer
TPU
A rubber you can injection mold and print.
Published values for unfilled grades at 23 °C unless stated. Confirm against the supplier datasheet for the grade you specify.
What it is
TPU is a block copolymer with hard and soft segments. The hard segments behave like a thermoplastic and let the material be molded and remelted; the soft segments give rubber-like elasticity. You get elastomer behavior without the cure time of thermoset rubber.
It has the best abrasion resistance of any common polymer, and it survives oils and greases that attack natural rubber.
Where it is used
- Seals, gaskets, and bellows
- Grips, bumpers, and overmolded soft-touch surfaces
- Wheels, castors, and rollers
- Cable jacketing and strain relief
- Printed flexible prototypes and living components
Processing notes
Dry 2–3 hours at 80–100 °C; TPU is very hygroscopic and molds badly wet.
Melt 190–230 °C, mold 20–40 °C. Softer grades need slower fill to avoid jetting.
Overmolding onto ABS, PC, or PC/ABS bonds chemically when the substrate is hot and the grade is matched. Confirm the pair before tooling.
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Design notes
Specify hardness in Shore A or D and state the test standard; datasheets differ by up to five points.
Allow for compression set on any part that stays under load. Design the seal groove to a standard fill ratio.
Undercuts can often be stripped from the tool without side actions, which saves real money.
Grades and variants
- Polyester based, better oil and abrasion resistance
- Polyether based, better hydrolysis and low-temperature performance
- Shore 85A, the general purpose overmolding hardness
- Glass filled for structural flexible parts
- Medical and food contact certified grades
Specifying this material?
Send your CAD and target volumes. We come back with a price, a lead time, and any material or design notes that would reduce either.