3D printing with thermoplastic polyurethane (TPU) filament opens up exciting possibilities for flexible and durable prints. TPU’s rubber-like properties allow it to bend, stretch, and compress in ways rigid plastics can’t. From phone cases to robotics parts, TPU enables new applications for 3D printing.
This guide covers everything you need to know about TPU 3D printing. Read on to learn what makes TPU special, how to print with it, and creative ways to use this flexible filament.
What is TPU Filament?
TPU is a type of thermoplastic elastomer (TPE). It contains long polymer chains that are loosely cross-linked, giving TPU high elasticity and shock absorption.
Unlike rigid plastics, TPU can stretch up to 5 times its original length. It quickly returns to its original shape when stress is removed. This flexibility makes TPU useful for applications that need to bend, compress, or endure repeated impacts.
At the same time, TPU maintains excellent abrasion resistance and durability. Printed TPU parts will last longer than rubber under frequent use and maintain their flexibility over time.
TPU also provides good chemical resistance and weatherability. It can withstand exposure to oils, greases, and sunlight without degrading. The material has high dielectric properties too, meaning it insulates electricity well.
Key Properties of TPU Filament:
- Highly flexible – Stretches up to 500%
- Excellent abrasion/tear resistance
- Good chemical resistance
- High impact strength and durability
- Abrasion/scratch resistant surface
- Excellent weathering properties
- High dielectric strength
TPU 3D printer filament comes in a range of shore hardnesses, usually between 85A-95A. The higher the number, the more rigid and dense the TPU. Harder TPU prints better but is less flexible.
Most TPU filaments also contain color pigments. You can find TPU in standard colors like black and white as well as bright hues for colorful prints. Specialty filaments feature glow-in-the-dark, magnetic, and even antimicrobial TPU materials.
TPU vs Other Flexible Filaments
TPU has some advantages over other flexible 3D printing filaments like Ninjaflex.
While Ninjaflex is extremely flexible, it lacks the abrasion and tear resistance of TPU. Prints made with Ninjaflex can split apart under too much stress. TPU holds up better over time.
TPU also has superior impact strength versus flexible materials like TPE. This makes it more suitable for functional parts that need to absorb and distribute shocks.
Lastly, TPU maintains its flexibility and durability across a wide temperature range (-40°C to 80°C). Other flexible options become stiff and brittle at temperature extremes.
For most applications calling for a flexible material, TPU offers the best all-around performance. The excellent abrasion resistance and durability are hard to match with other flexible filaments.
Printing with TPU Filament
While TPU is an exceptional material, it does require some special considerations when printing with it:
- Low printing speeds – Excess speed can cause TPU to bind in the extruder. Print at 25-35mm/s or lower for best results. Slow print speeds are necessary to prevent jams.
- All-metal hot ends – TPU’s flexible strands can erode the Teflon liners in standard hot ends. All-metal hot ends are strongly recommended. Some direct drive extruders also work well for flexible filaments.
- Enclosed printer – Open frame printers can have difficulty adhering TPU layers as they cool and contract. Printing in an enclosed chamber helps maintain ambient temperatures.
- No heated beds – Heated print beds cause too much melting and lead to poor first layer adhesion with TPU. Print on bare glass or PEI instead.
- No cooling fans – LetTING TPU cool slowly prevents over-contraction and warping. Disable active cooling fans and other cooling elements.
With the right printer and settings dialed in, TPU prints cleanly and accurately like any other material. It offers exceptional bridging capabilities too thanks to its flexibility. Fine details show up better with TPU versus other flexible options.
If you experience frequent clogging or poor bed adhesion with TPU, try drying the filament first. TPU can absorb ambient moisture which interferes with extrusion. A few hours in a filament dryer or oven at 50°C restores TPU to optimal printing condition.
Best Uses for 3D TPU Prints
The unmatched flexibility and durability of TPU make it ideal for:
Flexible seals, gaskets, and connectors – TPU’s air and water tightness allow it to replace rubber gaskets and seals. Print custom seals for pumps, pipes, tanks, lids, etc. TPU withstands compression and retains flexibility, creating a tight fit.
Protective cases and bumpers – TPU’s shock absorbing properties provide unbeatable impact protection for fragile items. TPU phone cases withstand bumps and drops without cracking. Print TPU cases for electronics, camera equipment, and other delicate objects. The material protects contents from sudden impacts.
Robotic parts – Actuators, grippers, and body panels with TPU withstand heavy use and repeated stresses that would crack ABS or PLA plastic. TPU provides long service life under continuous flexing motions. Use it for hinges, pivot points, and high wear components.
Prosthetic and orthotic devices – Engineering TPU’s flexibility makes it suitable for facial prosthetics, ear pieces, and custom orthopedic braces. The material conforms comfortably to the body while maintaining shape. Prototypes can be iterated quickly.
Shoe soles and insoles – TPU’s shock absorption works great for shoe components. Personalized TPU insoles provide cushioning tailored to the wearer. Make soles with treads and patterns impossible with injection molding. Use TPU’s flexibility in novel shoe designs.
Flexible vases, containers, and fun shapes – Add whimsy and functionality with TPU vases that deform when pressed. Or make collapsible bottles, foldable funnels, and other tools. TPU enables completely new use cases thanks to its elasticity and shape memory.
The applications for flexible TPU material are nearly endless. Anything that needs to bend, compress, or stretch becomes possible with TPU 3D printing. It excels anywhere high durability and abrasion resistance are also required.
Finishing TPU Prints
TPU requires little finishing thanks to its slick surface texture right off the print bed. Light sanding with fine grit paper smoothes layer lines and any small defects.
Unlike other materials, TPU sands easily without clogging papers or producing fine dust. A quick scuffing restores the matte surface texture.
Painting TPU works but requires specialty paints like plasti-dip. The flexibility of TPU can cause standard paints to crack and peel during bending. Primers can improve paint adhesion for occasional flexes.
To bond TPU prints, use superglues like Loctite specifically formulated for flexible materials. Cyanoacrylate glues work better than epoxies on TPU. Practice gluing scraps first before bonding final prints.
For a completely smooth finish, try vapor smoothing TPU with acetone. This melts the outer surface into a glossy finish that still retains flexibility. Results depend heavily on technique, so experiment with test prints first.
Safety Considerations
TPU emits low VOCs and has no major health risks associated with it. Still, take the same safety precautions as with any 3D printing material:
- Print and sand in a well-ventilated area
- Wear a mask/respirator when sanding prints
- No eating or drinking near the 3D printer
- Store filament properly away from food
- Wash hands after handling prints before eating
TPU is considered non-hazardous for skin contact. Those with latex allergies should not have issues with TPU but test by touching a small corner first.
Wrapping Up
From phone cases to robotics parts, TPU opens up new possibilities with its unmatched flexibility and durability. Keep this guide in mind when exploring printing with TPU filament. Follow the tips on printer settings, bed adhesion, appropriate uses, and finishing techniques.
With the right approach, TPU prints as easily as PLA or ABS while enabling applications impossible with rigid plastics. Expand your 3D printing horizons with TPU!
