TPU, or Thermoplastic Polyurethane, typically falls within a specific range on the shore hardness scale to define its softness.
Understanding TPU Softness
The softness or hardness of materials like plastics and rubbers is commonly measured using a Shore hardness scale. For flexible materials like TPU, the Shore A scale is frequently used. A lower number on the Shore A scale indicates a softer material, while a higher number indicates a harder material within that scale.
TPU Hardness Range
Based on common specifications, TPU usually exhibits a hardness between 60A and 90A on the Shore A scale.
| Material Type | Shore Hardness Scale | Typical Range |
|---|---|---|
| Flexible TPU | Shore A | 60A - 90A |
This range signifies that TPU can vary from relatively soft and very flexible (closer to 60A) to somewhat firmer but still flexible (closer to 90A), comparable to pencil erasers or rubber tires.
Implications of Softness for Printing
Generally speaking, the softer the filament is, the harder it is to print. This means TPUs on the lower end of the 60A-90A range can be more challenging for 3D printing compared to those on the higher end. They require careful handling, slower print speeds, and often direct drive extruders to prevent buckling or stretching during feeding.
Additional Properties of Flexible TPU
Beyond its variable softness, flexible TPU filaments possess desirable characteristics, as noted in material descriptions:
- They are usually very resistant to wear (scratching).
- They stay flexible even in cold environments.
- They show great resistance against various solvents.
These properties make TPU a versatile material for applications requiring durability, flexibility in challenging conditions, and resistance to chemical exposure.
