TPU Filament Properties: Flexibility Meets Durability

Understanding TPU and Its Composition

Thermoplastic Polyurethane (TPU) is a flexible, durable material used in 3D printing. As a thermoplastic elastomer, it combines elasticity with the mechanical strength of plastics. Its molecular structure—a block copolymer of hard and soft segments—enables a wide range of Shore hardness grades. TPU can be processed using techniques like FDM or SLS, offering dimensional stability, chemical resistance, and resilience under varying temperatures.

Unlike PLA, TPU can stretch extensively without breaking, making it ideal for flexible, shock-resistant components. Its ability to be stretched and compressed while retaining its original shape opens new doors in additive manufacturing.

Classifying TPU by Shore Hardness

• Soft TPU (85A–88A): Highly elastic, stretchable up to 700–1000%, perfect for phone cases, cable sleeves, and wearable devices.
• Medium TPU (90A): Balanced flexibility and strength, widely used for insoles, gaskets, and shock absorbers.
• Hard TPU (95A): More rigid while still flexible, ideal for gears, enclosures, and structural supports.

This adjustability in hardness makes TPU a versatile material for engineers who want to tune tactile and mechanical properties for specific designs.

Benefits and Drawbacks

Advantages

• Excellent flexibility – bend and stretch without breaking
• Strong layer adhesion for unified prints
• High impact and wear resistance
• Chemical resistance (oils, acids, solvents)
• Environmentally friendly due to durability and recyclability

Limitations

• Challenging for beginners – prone to jamming in Bowden extruders
• Sensitive to moisture, requires proper storage
• Limited hydrolysis resistance in wet environments
• Requires slower print speeds and optimized extruders

TPU vs PLA: Property Comparison

TPU Printing Guidelines

• Extrusion temperature: 215–240 °C
• Print speed: 80–100 mm/s (direct drive)
• Retraction: Reduce by 10–20%
• Nozzle: 0.4 mm recommended
• Bed: Use cold PEI textured plate
• Storage: Airtight container, RH < 60%
• Cooling fan: Cooling is needed in case of a lot overhangs

Real-World Applications of TPU Filament

• Footwear: Sports shoes, soles, and uppers requiring flexibility and abrasion resistance.
• Sports Equipment: Bike grips, climbing gear, kayak parts, and protective padding.
• Engineering Plastics: Gears, bushings, and brackets that replace metal parts.
• Automotive Interiors: Steering wheel covers, shift knobs, dashboard components.
• Medical Devices: Oxygen masks, catheters, braces, and skin-contact devices.
• Consumer Products: Flexible phone cases, grips, tool handles, and wearables.