TPU 92A (Thermoplastic Polyurethane, Shore 92A) for FDM

Material Profile: TPU 92A (Thermoplastic Polyurethane, Shore 92A) for FDM

FDM Engineering Material Technical Report Series

Compiled from manufacturer technical datasheets and peer-reviewed literature

Abstract—TPU 92A is a slightly softer thermoplastic polyurethane than the more common 95A grade — Shore 92A on the durometer scale. The reduced hardness comes from a higher proportion of soft polyol segments versus hard urethane segments. The result is improved rebound, softer touch, and greater flexibility, balanced against modestly more difficult printing (the filament is more prone to buckling in Bowden extruders). Suppliers include Recreus FilaFlex 92A, Polymaker PolyFlex™ TPU90, NinjaTek Edge (90A), and Filaflex Conductive (92A).

Index Terms—additive manufacturing, FDM, thermoplastic polyurethane, TPU 92A, soft elastomer.

I.  MATERIAL IDENTIFICATION

This section establishes the canonical names and commercial designations under which the material is supplied.

A.  Designation

Trade name: TPU 92A (generic). Examples: Recreus FilaFlex 92A, NinjaTek Edge 90A (very close in hardness), Filaflex Conductive 92A.

B.  Full Chemical Name

Thermoplastic polyurethane — segmented block copolymer with ~30–35% hard urethane segments and ~60–65% soft polyol segments (lower hard fraction than 95A).

C.  Aliases and Alternative Designations

II.  COMPOSITION AND MOLECULAR STRUCTURE

A.  Empirical Chemical Formula

Idealised: [-CO-NH-R-NH-CO-O-R'-O-]ₙ. Hard segment fraction reduced by ~5% vs 95A; soft segment fraction increased correspondingly.

Fig. 1.  Repeating unit / structural schematic of the polymer matrix.

Fig. 2.  Schematic of the single-phase polymer (no reinforcement).

B.  Composition Breakdown

TABLE I
 COMPOSITIONAL BREAKDOWN OF TPU 92A (TYPICAL / PER SUPPLIER DATASHEET)

III.  MECHANICAL PROPERTIES — XZ PRINT DIRECTION

In the XZ orientation the tensile load is applied parallel to the deposited rasters; for fibre-reinforced grades this is the strongest orientation because the fibres align preferentially along the extrusion direction.

TABLE II
 MECHANICAL PROPERTIES — XZ ORIENTATION (TPU 92A)

IV.  MECHANICAL PROPERTIES — ZX PRINT DIRECTION

In the ZX orientation the tensile load is applied perpendicular to the print layers, so failure occurs through inter-layer (Z) bonds. Properties are markedly lower than in XZ — this anisotropy is intrinsic to FDM.

TABLE III
 MECHANICAL PROPERTIES — ZX ORIENTATION (TPU 92A)

Like 95A, anisotropy primarily affects elongation rather than modulus or hardness. The lower hard-segment fraction makes inter-layer welding marginally more sensitive to print parameters.

V.  RECOMMENDED PRINT PARAMETERS

Values summarised below give consensus operating windows from public datasheets. Specific suppliers may differ within ±10 °C; the supplier datasheet always supersedes this table.

TABLE IV
 RECOMMENDED PRINT TEMPERATURE RANGES FOR TPU 92A

VI.  GLASS TRANSITION TEMPERATURE (TG)

Reported / typical Tg: ≈ -35 °C (soft segment); hard segment Tg ≈ 70 – 90 °C.

Soft segment Tg is slightly lower than 95A (more polyol content), giving better low-temperature flexibility (down to -40 °C). Upper service limit is correspondingly slightly lower (~70–80 °C) due to reduced hard-segment fraction.

VII.  HEAT DEFLECTION TEMPERATURE (HDT)

Heat deflection temperature is the temperature at which a standard bar deflects 0.25 mm under a specified flexural load (ASTM D648 / ISO 75).

TABLE V
 HEAT DEFLECTION TEMPERATURE OF TPU 92A UNDER STANDARD TEST LOADS

VIII.  DISTINGUISHING CHARACTERISTICS AND STANDARDS

A.  Softer, higher rebound than 95A

The 3-point lower Shore A hardness translates to substantially higher elastic rebound and a more 'rubbery' tactile feel. Specifically suited to applications where a 95A part feels too hard or where higher cushioning is required.

B.  Conductive variants available (e.g., FilaFlex Conductive 92A)

Recreus offers a conductive 92A variant where the polymer is loaded with conductive carbon black to enable wearable electronic and sensor applications. Volume resistivity ~10² Ω·cm in the conductive grade.

C.  Print difficulty trade-off

The increased flexibility comes at the cost of harder printing — the filament buckles more easily in Bowden tubes and requires a direct-drive extruder for reliable feeding. Print speeds typically 5–10 mm/s slower than 95A.

D.  Chemical and abrasion resistance

Similar to 95A: resistant to oils, greases, fuels, alcohols. Slightly more sensitive to high-temperature chemicals due to reduced crystallinity in the hard segment.

IX.  REPRESENTATIVE APPLICATIONS

TPU 92A is typically deployed in the following applications:

1)  Soft-touch consumer product surfaces: Phone case grips, electronic device covers, ergonomic handles.

2)  Wearable / conductive sensor components: FilaFlex Conductive 92A — flexible electrode and EMG sensor pads.

3)  Higher-rebound vibration damping: Anti-vibration mounts where 95A is too stiff for the application frequency band.

4)  Custom-fit insoles and orthotics: Greater conformability than 95A; closer to traditional shoe-insole rubber durometer.

(Source : Unionfab)

5)  Soft sealing surfaces and bellows: Where 95A is too rigid to deflect under low-pressure differentials.

Photographs of representative parts in these applications are not reproduced here for copyright reasons; the table below provides direct manufacturer / case-study URLs where original imagery and project descriptions can be viewed.

TABLE VI
 SUGGESTED IMAGE / CASE-STUDY SOURCES

X.  REFERENCES

[1]  Recreus, “FilaFlex 92A Material Data Sheet,” 2024. Available: https://recreus.com/en/12-filaflex

[2]  Recreus, “Filaflex Conductive 92A Datasheet,” 2024.

[3]  NinjaTek, “Edge TPU Datasheet (90A),” 2024. Available: https://www.ninjatek.com/products/ninjatek-edge/

[4]  Polymaker, “PolyFlex™ TPU90 Material Data Sheet,” 2024.

[5]  ASTM D638-14, ASTM International, 2014.

[6]  ASTM D2240, “Standard Test Method for Rubber Property — Durometer Hardness,” ASTM.

[7]  ISO 7619-1, “Rubber, vulcanized or thermoplastic — Determination of indentation hardness — Shore hardness,” ISO.