Filament Guide
TPU Filament Guide
The flexible material. Rubber-like, impact-absorbing, durable.
Last updated: March 2026
TL;DR
- Flexible, rubber-like material — great for phone cases, gaskets, vibration dampeners, and grips
- Needs a direct drive extruder — Bowden tubes let the filament buckle and jam
- Print slow: 20-40mm/s at 220-250°C, no retraction or minimal retraction
- Shore 95A is the standard hardness — lower A = more flexible, higher = stiffer
TPU
Thermoplastic Polyurethane
The flexible material. Rubber-like, impact-absorbing, durable.
Intermediate
Flexible
TPU bends, stretches, bounces back, and handles impacts that would shatter PLA or PETG. It's rubber-like but melt-processable — the hard urethane segments give it shape, the soft polyol segments give it flex.
The trade-off is printability. TPU's flexibility makes it buckle in the extruder, especially on Bowden setups where the tube gives the filament room to compress and kink. Direct drive is strongly recommended. Expect to print at 20-30mm/s.
Hardness is measured in Shore A - consumer TPU filaments range from ~87A (very flexible, almost silicone-like) to ~98A (only slightly flexible). Most general-purpose TPU sits around 95A.
Chemistry
Block copolymer: hard urethane segments + soft polyether or polyester segments
Print Temp
Hardness Range
87A-98A Shore - lower = softer. Most common: 95A[2]
Heat Resistance
Softens at ~80-120°C depending on formulation
Abrasion Resistance
Excellent - used for wear pads, seals, and tyre-contact surfaces
Extruder Type
Direct drive strongly preferred.[1] Bowden: use only 95A+ and go very slow.
Pros
- Flexible, elastic - returns to shape after deformation
- Exceptional impact and abrasion resistance
- Good chemical resistance (oils, fuels)
- Usable in low temperatures (stays flexible at −40°C)
- Soft surface feel - ideal for grips and wearables
Cons
- Difficult to print - requires slow speeds
- Bowden setups struggle or fail
- Highly hygroscopic - must be dried before printing
- Strings and oozes easily
- Cannot be printed with rigid part infill strategies
- Hard to support and remove supports cleanly
Best Used For
Phone cases
Gaskets & seals
Grip surfaces
RC tyre inserts
Vibration dampeners
Wearables & straps
Bump stops
Cable strain relief
Flexible hinges
Niche Tips
Drying is non-negotiable. Wet TPU pops, bubbles, and produces weak, rough prints. Dry at 50-60°C for 4-8 hours before every print session if stored open.
Disable retraction or use very minimal retraction (0.5-1mm direct drive). High retraction causes filament to coil inside the extruder.
Infill pattern matters: Gyroid or honeycomb infill produces better elastic behavior than grid. For very flexible parts, use 10-20% gyroid.
TPU bonds to itself chemically - multi-layer welds are strong. However it barely bonds to PLA/PETG, which is useful for printing sacrificial rigid supports that peel cleanly.
Storage & Humidity
Target: below 20% RH. TPU absorbs way more moisture than PETG or ABS. Wet TPU bubbles, loses layer adhesion, and strings everywhere. Store sealed with fresh desiccant — always.
Drying: 65-75°C for 8 hours. TPU is temperature-sensitive - don't exceed 75°C or the filament can soften and tangle on the spool.
TPU is one of the materials most worth running from a drybox during printing, especially in humid climates. The quality difference between dry and wet TPU is dramatic.
Bed Adhesion
Best surfaces: PEI (smooth or textured), blue painter's tape. TPU adheres well to most surfaces without adhesion aids.
Recommended bed temp: 30-60°C. Higher end of this range improves adhesion for flexible prints that can peel during printing. TPU doesn't warp, so bed temp is less critical than for rigid materials.
Release: Simply flex the build plate. Flexible TPU prints pop off textured PEI with very little force. Avoid using adhesion aids that make release harder - TPU can tear if over-adhered.
Variants & Special Types
TPU 95AStandard shore hardness - flexible but firm. The most common TPU variant and the best starting point. Good balance of flexibility and printability.
TPU 90ASofter than 95A. More flexible, but harder to print - more prone to buckling in Bowden tube setups. Direct drive extruders strongly recommended.
TPU-CFTPU with carbon fiber. Increased stiffness while maintaining some flexibility. Niche use for semi-rigid seals and vibration dampeners that need structure.
TPU ESDElectrostatic dissipative TPU for flexible ESD-safe parts. Used in electronics manufacturing for protective covers and grips.
TPU RapidFaster-printing TPU variant with modified flow. Reduces the speed penalty that makes TPU slow to print.
References
- Prusa Knowledge Base - Flexible Materials (TPU/TPE). Print temperatures, direct drive requirements, and speed recommendations. help.prusa3d.com/article/flexible-materials-tpu-tpe_2057
- Bambu Lab Wiki - Filament Guide Material Table. Shore hardness scale and printing parameters for flexible filaments. wiki.bambulab.com/en/general/filament-guide-material-table
Frequently Asked Questions
Does TPU work with Bowden extruders?
Soft TPU (below 90A Shore hardness) is very difficult to print reliably with a Bowden setup because the long PTFE tube allows the flexible filament to compress, buckle, and jam. Harder TPU (95A) can work with Bowden if you print slowly (15-25mm/s) and use a constrained filament path. Direct drive extruders are strongly recommended for all TPU printing.
What Shore hardness should I start with?
Start with 95A TPU. It is the most common hardness, the easiest to print, and works for most flexible applications like phone cases, bumpers, and grips. 85A is noticeably softer (similar to a rubber band) but much harder to print. Only go below 90A once you are comfortable with 95A and have a direct drive extruder.
Why is my TPU stringing?
TPU strings easily because it is elastic and does not retract cleanly like rigid filaments. Reduce stringing by disabling or minimizing retraction (0-2mm for direct drive), lowering print temperature by 5°C increments, increasing travel speed, and enabling wipe/coasting. Some stringing is normal with TPU and can be cleaned up with a heat gun on low.
Is TPU waterproof?
TPU is highly water-resistant and does not absorb water significantly in use. Printed TPU parts work well as seals, gaskets, and waterproof enclosures. However, FDM layer lines may allow water to seep through at high pressure. For fully watertight prints, use more walls (4+), higher infill, and consider coating the part.
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