TPU Material: Thermoplastic Polyurethane Properties and Applications

Thermoplastic polyurethane (TPU) occupies a unique position in the engineering materials landscape—rigid enough to be injection molded and CNC machined like a plastic, elastic enough to function as a rubber. This versatility makes TPU one of the fastest-growing elastomers in manufacturing, found in everything from smartphone cases to hydraulic seals.

What Is TPU?

TPU is a block copolymer consisting of alternating hard segments (derived from diisocyanates like MDI or TDI) and soft segments (polyesters or polyethers). The hard segments create physical crosslinks that give the material its shape and modulus at room temperature; the soft segments provide flexibility and elasticity.

Unlike vulcanized rubber, these crosslinks are physical—not chemical—meaning they are reversible when heated above the melting point of the hard segment. This allows TPU to be melt-processed like a thermoplastic: injection molded, extruded, or 3D printed, then reprocessed at end-of-life.

Key Properties of TPU

Property	Typical Range	Notes
Hardness (Shore A)	60A-75D	Spans rubber to semi-rigid
Tensile Strength	20-55 MPa	Higher than most elastomers
Elongation at Break	300-800%	Excellent flexibility
Abrasion Resistance	Excellent	Better than rubber, comparable to polyurethane
Oil Resistance	Good-Excellent	Polyester TPU better than polyether
UV Resistance	Poor to Moderate	UV stabilizers recommended for outdoor use
Operating Te mperature	-40 to +80 degrees C (continuous)	Short-term to 120 degrees C

Types of TPU

Polyester TPU

The most common type. Polyester TPUs offer excellent oil and fuel resistance, good mechanical properties, and cost-effective pricing. They are the preferred choice for hydraulic seals, pneumatic tubing, and automotive applications where oil contact is expected.

Polyether TPU

Superior hydrolysis resistance and low-temperature flexibility compared to polyester types. Polyether TPUs m

aintain flexibility at temperatures as low as -60 degrees C. Preferred for medical devices, marine applications, and outdoor use where moisture exposure is a concern.

Polycaprolactone TPU

Premium performance with excellent mechanical properties and low temperature resistance. More expensive but used in demanding applications like ski boots, military equipment, and high-performance footwear.

TPU vs. Other Elastomers and Plastics

• vs. Silicone: TPU has better tensile strength and abrasion resistance. Silicone has superior temperature resistance and biocompatibility.
• vs. Rubber (EPDM, NBR): TPU is thermoplastic (reprocessable, faster processing) vs. thermoset rubber (vulcanization required). TPU has better oil resistance and transparency options.
• vs. TPV (Thermoplastic Vulcanizate): TPV offers better long-term seal performance and compression set resistance. TPU has better abrasion resistance and transparency.
• vs. Soft PVC: TPU is free of plasticizers (no leaching, no odor) and has better low-temperature performance. More expensive but superior for critical applications.

TPU in Manufacturing

CNC Machining TPU

TPU’s flexibility makes CNC machining challenging—parts deflect under cutting forces and grip poorly in chucks. Use sharp tools, slow feed rates, and flooded coolant. Wax-like lubricants reduce heat. We typically recommend molding TPU over machining for complex geometries.

Injection Molding TPU

TPU is injection moldable but requires specific processing knowledge: barrel temperature 190-230 degrees C, mold temperature 20-50 degrees C, and low injection speed to prevent flash. TPU’s high viscosity requires careful gate design. Short shots are common if venting is inadequate.

3D Printing TPU

TPU filaments (Shore 95A-60D) print on standard FDM printers with heated beds at 220-260 degrees C. Flexibility makes bed adhesion challenging—use PEI sheets or adhesion promoters. Slow print speeds (20-40 mm/s) prevent nozzle clogging. TPU 95A is the most common and easiest to print.

Our TPU Manufacturing Services

We offer TPU parts via:

• Injection molding of TPU in prototype and short-run quantities (500-10,000+ pcs)
• TPU 3D printing via FDM for functional prototypes and custom parts
• CNC machining for simpler geometries where molding setup costs are not justified

Related Articles

Explore more manufacturing insights: Injection Molding Process.

Frequently Asked Questions

What is the difference between TPU and TPE?

TPE is a broad category encompassing all thermoplastic elastomers—TPU is one specific type within that category. TPU specifically refers to polyurethane-based chemistries with excellent abrasion resistance and mechanical properties. Other TPEs include TPV (thermoplastic vulcanizate), TPO (thermoplastic olefin), and SEBS-based compounds.

Is TPU food safe?

Some TPU grades are FDA-compliant for food contact, but this is grade-specific. Medical-grade TPU formulations are available for implants and drug-delivery devices. Always verify with the material data sheet and your regulatory requirements.

Can TPU be overmolded onto rigid plastics?

Yes. TPU bonds well to ABS, PC, and PA through overmolding. The key is matching processing temperatures and ensuring the substrate has appropriate surface energy for adhesion. Additive primers can improve bonding on difficult substrates.

What hardness of TPU should I choose?

Shore 60A-75A: Soft-touch grips, seals, footwear (high flexibility)

Shore 80A-90A: Hoses, tubing, protective cases (moderate rigidity)

Shore 95A-55D: Structural components, gears, wear pads (semi-rigid)

Generally, higher hardness means better dimensional stability and processing, but reduced flexibility. Match the hardness to the functional requirements of the part.