A TPU coiled cable sample can look acceptable on a desk and still fail in the buyer’s equipment. The cable may not reach the working position, may recover slowly, or may place repeated stress on the connector exit. A useful sample approval process therefore measures the cable in its relaxed, extended and recovered states.
Quick Answer
Before approving a TPU coiled cable sample, record its relaxed coil length, usable working extension, straight-tail lengths, coil diameter and cable OD. Then check continuity, connector retention, strain relief, rebound after repeated extension and the condition of the coil after packaging. Acceptance limits should be agreed from the drawing or approved sample rather than assumed from a generic ratio.
1. Establish the Measurement Method
Write down where every dimension starts and ends. Clarify whether relaxed length includes the straight tails and connectors, and define the maximum working extension without pulling the cable completely straight. Use the same conditioning time and measurement method for the approval sample and production inspection.
| Sample check | What the buyer should define | Risk it controls |
|---|---|---|
| Relaxed length | Measurement points and allowed tolerance | Fit and storage space |
| Working extension | Required reach under normal use | Overstretch and excessive pull |
| Straight tails | Length and exit direction at both ends | Routing and connector stress |
| Coil geometry | Outer diameter, pitch and appearance | Interference and inconsistent recovery |
| Cable construction | Conductors, gauge, shield and jacket requirement | Electrical and mechanical mismatch |
2. Test Stretch and Rebound in the Real Use Position
Extend the sample to the agreed working distance, hold it for the agreed period and release it without twisting the connectors. Record the recovered length after a consistent waiting time. Repeat the check enough times to reveal obvious loss of coil memory, jacket whitening, kinks or tail rotation. The number of cycles and acceptance limit must come from the buyer’s application requirement; do not treat an unsupported cycle-life claim as an approval criterion.
3. Inspect Connector and Strain Relief
- Confirm connector model, keying, pinout and mating fit.
- Check whether the straight tail prevents the first coil from bending against the overmold.
- Inspect the jacket-to-overmold transition for gaps, sharp edges and visible deformation.
- Perform the electrical and retention checks specified for the project.
4. Check Electrical Function and Packaging
Continuity and wiring checks should follow the approved pinout. Where shielding, current, data or environmental performance matters, agree on the relevant test method before quotation. Package the approved sample in the proposed production format and check whether ties, bags or carton pressure distort the coil or mix product variants.
Buyer Checklist Before Sample Approval
- Drawing revision and application confirmed
- Relaxed and working lengths measured by an agreed method
- Coil diameter, cable OD and straight tails recorded
- Connector, pinout and strain relief checked
- Stretch and recovery acceptance criteria documented
- Continuity and project-specific tests completed
- Packaging and label sample reviewed
- Approved sample retained as a production reference
Related Products and RFQ
Compare custom TPU coiled cable options before choosing conductor, connector and coil geometry. To review a real project, send a drawing, sample photo and target working extension for an RFQ and sample plan.
Real Coiled Cable Production Case
See an anonymized batch record covering coiled cable preparation, relaxed-length inspection, conductor details and protective packaging. Only visible production evidence is described; no confidential customer or unsupported performance claim is included.