BASF 3D Ultrafuse TPU 95A Fused Filament is a thermoplastic polyurethane monofilament formulated for fused filament fabrication. The product is supplied in 1.75 mm and 2.85 mm nominal diameter formats on 750 g sealed spools. It is specified at Shore 95 A hardness and a density of 1.21 g/cm³ per ISO 1183-1. The material is intended for functional flexible polyurethane parts such as seals, protective covers, vibration dampers, cable strain-relief components, and pneumatic gripper pads. Compared with rigid PLA, PETG, or ABS feedstocks, the filament has lower tensile modulus, higher elongation, and higher surface friction in unlubricated contact. Compared with softer TPU grades below 90 A, the 95 A hardness reduces cold-end buckling, lowers drive-gear surface tack, and improves print-path dimensional stability.

What Moisture Thresholds and Drying Procedures Apply Before Extrusion?

Thermoplastic polyurethane is hygroscopic. Water uptake at 23 °C and 50% RH may exceed 0.2 wt% after 48 h in uncontrolled storage. Karl Fischer titration per ISO 15512 of improperly stored filament frequently shows surface moisture levels sufficient to produce steam nucleation at melt temperatures above 180 °C. The BASF material datasheet recommends pre-drying at 60 °C for 4 h in a forced-air oven with dew point below -20 °C. For material stored at relative humidity above 60%, drying time should be extended to 12 h. Production experience on direct-drive extruders with hardened steel drive gears shows that wet TPU causes extruder backpressure fluctuation, irregular filament swell, and interlayer weld-line voids at layer heights below 0.15 mm. In Bowden feed systems, moisture-softened filament is more prone to cold-end buckling, especially at retraction speeds above 30 mm/s. For high-throughput systems with multiple spools, feed from a sealed dry-box maintained below 10% RH is used to reduce batch-to-batch moisture variation.

Under monotonic tensile loading of printed specimens after conditioning at 23 °C and 50% RH, published datasheet values place tensile stress at break between 30 MPa and 45 MPa according to ISO 527-2, with elongation at break greater than 400%. Tear resistance is reported between 80 kN/m and 110 kN/m per ISO 34-1, and abrasion loss is below 100 mm³ per ISO 4649. These values are geometry- and print-orientation-dependent. Specimens printed in the XY orientation with 0.15 mm layers and 100% rectilinear infill generally fall in the upper end of the reported range. Table 1 summarizes representative physical and mechanical parameters from supplier data and technical literature.

Thermomechanical Processing Boundaries in Fused Filament Fabrication

Extrusion processing of BASF 3D Ultrafuse TPU 95A Fused Filament requires nozzle temperatures from 210 °C to 230 °C. At temperatures below 210 °C, melt viscosity is not sufficiently reduced for consistent extrusion through a 0.4 mm brass nozzle at speeds above 25 mm/s. This condition produces skipped steps on ungeared direct-drive motors and starved-layer surface defects. At temperatures above 235 °C, thermal decomposition of the urethane soft segment accelerates, causing yellowing, viscosity drift, and reduced interlayer fusion. Bed temperature is maintained at 40–60 °C on glass or PEI-coated aluminum substrates. For large, thin-walled parts with long tool paths, an enclosed chamber held at 30–40 °C reduces part lifting and improves first-layer consistency.

Filament feed-path design is decisive. This grade has lower column stiffness than PLA or PETG. In Bowden systems, 2.85 mm diameter feedstock with a constrained guide tube of 2.0 mm inner diameter is preferred. Unsupported length should be minimized. Retraction distances are reduced to 2–3 mm with retraction speed 20–25 mm/s. Direct-drive systems can operate with 0.5–1.2 mm retraction at 20–35 mm/s. Pressure advance values from 0.1 s to 0.3 s reduce seam artifacts without overdriving the flexible filament. Print speeds above 40 mm/s for 1.75 mm feedstock may induce buckling between the feeder and hot end. Speeds above 20 mm/s for walls under 0.8 mm require reduced layer height and lower fan speed to maintain interlayer diffusion.

Interlayer adhesion in TPU 95A is controlled by cooling rate and melt residence time. If the part is subjected to 100% cooling fan flow at speeds below 20 mm/s, the surface solidifies before adjacent tracks are deposited, yielding low weld-line toughness. In low-fan configurations, the melt remains above the soft-segment crystallization temperature for longer, allowing chain diffusion across the interface. On open-chassis machines, fan speed is therefore limited to 0–30% for functional parts. Layer heights between 0.10 mm and 0.20 mm produce the most consistent sidewall fusion. Layer heights above 0.30 mm create insufficient interfacial pressure and lower Z-direction elongation by approximately 30% relative to XY specimens.

When Print Head Travel Speed Exceeds 40 mm/s, Dimensional Deviation Is Governed by Feeder Tension and Melt Elasticity

Melt elasticity of TPU 95A produces die swell after the nozzle exit. At low shear rates, die swell is moderate. At linear speeds above 40 mm/s, the extrudate can expand by 10–15% beyond nominal nozzle diameter, causing overextrusion at perimeter boundaries unless flow-rate compensation is adjusted. The effect is more pronounced with 0.8 mm nozzles than with 0.4 mm nozzles because the larger orifice retains less backpressure. Dimensional deviation in the XY direction can be held within ±0.25 mm for parts under 100 mm length when speed is below 35 mm/s. Above that speed, hole ovality and corner overshoot are common unless linear advance is tuned per spool. The soft-segment molecular weight distribution affects shear viscosity and die swell; supplier batch control is specified through melt volume rate tolerance, but published data for this specific configuration is limited.

Comparative Position Against 85A TPU and PLA-Based Flexible Materials

Selection between BASF 3D Ultrafuse TPU 95A, softer TPU grades, and PLA-based flexible filaments is governed by hardness, feed-path difficulty, processing temperature, and service environment. Table 2 presents representative offsets rather than specification limits.

Compared with PLA and PETG, the tensile modulus of this TPU is lower by roughly one to two orders of magnitude, permitting large recoverable deformation without cracking. Compared with PLA-based flexible filaments, this TPU exhibits superior tear strength and elongation but higher moisture sensitivity and a narrower extrusion-temperature window. Compared with softer TPU grades below 90 A, the 95 A hardness reduces extruder filament buckling, lowers surface tack, and permits slightly higher print speeds on direct-drive machines. However, tear resistance and elongation are reduced relative to 85 A and 80 A TPUs, which remains a design trade-off in applications requiring extreme stretching.

Seals, gaskets, dust covers, cable strain-relief elements, vibration dampers, pneumatic gripper pads, and sports footwear prototypes are built directly from this filament. In functional testing, parts printed with 100% infill and 0.15 mm layer height have been evaluated against injection-molded TPU using ISO 527-2 and ISO 34-1. Printed parts typically retain 70–85% of datasheet tensile strength in the XY orientation and 50–70% in the Z orientation because layer interfaces act as stress concentrators. Dry abrasive wear resistance is suitable for low-pressure conveying sleeves and soft jaws. Direct contact with strong polar solvents, including acetone, methyl ethyl ketone, ethyl acetate, and chlorinated hydrocarbons, should be avoided because these agents swell the soft segment and reduce tear strength. Continuous service in air above 70 °C or in hot water above 60 °C is not recommended without part-specific validation. For applications requiring food-contact compliance, this specific BASF grade does not carry a universal FDA 21 CFR 177.2600 or EC 10/2011 certification; users must validate the compounded formulation and printed surface under their own regulatory scope. Compliance with REACH Regulation EC 1907/2006 and RoHS Directive 2011/65/EU is documented in the safety datasheet for the filament feedstock, while printed parts require re-evaluation for final-article obligations.