TPU Flexible Filament: Shore A 85A vs 95A for 3D Printed Parts

Thermoplastic Polyurethane (TPU) is a flexible elastomer widely used in FDM 3D printing for parts requiring rubber-like flexibility and durability. TPU is specified using Shore A hardness ratings, with TPU 85A being softer and more flexible while TPU 95A is firmer and more resistant to abrasion. Understanding durometer ratings helps designers select the appropriate material grade for their specific application.

Shore A durometer measures material hardness by testing the resistance of the material to indentation. The scale ranges from 00 for very soft gels to 100 for very hard rubber. TPU 85A has a Shore A hardness of 85, placing it in the soft to medium range that feels similar to a car tire tread. TPU 95A has a Shore A hardness of 95, similar to a hard rubber wheel or industrial roller. The difference in hardness affects flexibility, tactile feel, and abrasion resistance.

TPU 85A is ideal for parts that require maximum flexibility such as phone cases, protective covers, seals, and gaskets. The softer material absorbs vibration effectively and provides good grip surfaces. However, TPU 85A prints at lower temperatures around 210 to 230 degrees Celsius and requires careful calibration to avoid stringing and poor layer adhesion. Parts printed with TPU 85A may compress more under load but recover their shape after the load is removed.

TPU 95A offers better abrasion resistance and structural support while maintaining flexibility. This grade is suitable for functional parts requiring semi-rigid behavior such as hinges, cable guides, and vibration mounts. TPU 95A prints at higher temperatures around 220 to 240 degrees Celsius and generally exhibits better layer adhesion and dimensional stability compared to softer grades. Parts maintain their shape under moderate loading while still bending rather than fracturing.

Printing flexible filaments like TPU requires adjustments to standard FDM settings regardless of grade. Lower print speeds around 20 to 30 millimeters per second reduce filament grinding and ensure consistent extrusion. Direct drive extruders generally perform better than bowden setups for flexible materials because the shorter filament path reduces buckling. Proper bed adhesion using materials like PEI sheets or glue sticks prevents warping while allowing part removal after printing.