“Rubber-like” describes expected behaviour without specifying a material. TPU means thermoplastic polyurethane, a thermoplastic elastomer supplied in different grades. It can feel rubber-like, but the name does not establish hardness, stretch, recovery, sealing or service life. Describe the motion, geometry and environment before comparing a particular grade.
Download the English project worksheet. Open it as UTF-8 CSV, replace the guide context with your project inputs and record observations separately from acceptance decisions. Blank cells do not indicate a passed check.
Hardness does not determine the whole part's flexibility
Shore hardness is measured on a specified scale under defined conditions. Compare like scales and test conditions. A thin lip and a solid block of the same grade bend differently. The material chooser lets you describe a preference without assuming that a particular grade is available.
Identify the main motion: bending, compression, stretching or twisting. State required displacement and repetition. For a cable opening, record its size before insertion, largest opening while the connector passes and opening after a defined recovery time. Without a force measurement, do not present “easy” or “stiff” as a measured material property.
Define recovery as an acceptance rule
Specify how soon the shape must recover and the permanent change you can accept. Softness alone does not prove suitable resilience. In the fictional example below, the opening may remain at most 1 mm wider after 60 seconds. That is a chosen requirement, not measured TPU performance.
Record this in the prototype assessment. If the need is toughness in a moving part rather than soft compression, compare the nylon selection questions before choosing a material family.
Compare exact grades and representative geometry
The cited UltiMaker datasheet concerns TPU 95A and reports values with particular methods and orientations. “95A” cannot be translated into a guaranteed bend angle for your part. Ask about the exact offered grade.
Keep the critical geometry in the trial
Draw wall thickness, voids and load direction. For a flexible cable lip, record slot width, lip thickness, unsupported length and fillets. If comparing thickness variants, keep grade, orientation and the rest of the geometry unchanged. Print orientation and layer structure also matter.
Specify the actual environment
Record temperature, moisture, outdoor exposure, cleaning and oil or chemical contact. Check compatibility for the exact grade. A family name does not establish a seal, food-contact suitability or safety performance.
Planning example: a flexible cable opening
A fictional cable guide must pass a 14 mm connector attached to a 6 mm cable. Its lip starts 12 mm open, may open temporarily to 16 mm and must return to no more than 13 mm after 60 seconds. The cable remains in place. This is neither a seal nor a safety component.
| Requirement | Planned value | Trial observation required |
|---|---|---|
| Cable diameter | 6 mm | Cable passes without damage |
| Connector width | 14 mm | No tearing during insertion |
| Initial opening | 12 mm | Measure the reference |
| Largest opening | At most 16 mm | Inspect for damage |
| Opening after 60 seconds | At most 13 mm | No more than 1 mm permanent difference |
| Lip thickness and grade | To be selected | Record one exact variant |
These are requirements, not results. An empty measurement column means no material or geometry has been accepted.
Test the critical movement before ordering quantities
Use the same critical thickness and movement direction in the trial. Measure with the same instrument before insertion, at the controlled maximum deformation and after 60 seconds. Change one factor at a time and record brand, grade and revision. Tearing, white stress marks, excessive permanent deformation or uncontrolled force means stop and review the geometry or grade.
Take the three states and sketch to the material selection discussion. If recovery is the main uncertainty, request a prototype with representative geometry and an agreed action. Unknown exposure or injury risk needs assessment first. Passing the trial confirms only that defined test, not sealing ability or lifetime.