Custom Spiral Springs - Acceptance by Sampling Plan
Custom Spiral Springs sampling plan
,Wire Forming spiral springs
,Custom spiral springs acceptance
Custom Spiral Springs - Acceptance by Sampling Plan
Product Introduction
TOPONE produces custom stainless steel spiral springs made to customer drawings, wound from certified spring wire in 0.15-12 mm diameters. For made-to-drawing parts the decisive question is not the datasheet but the acceptance plan: what is checked, on how many pieces, and what happens when a batch fails. This page sets out the sampling and inspection practice we apply, so it can be written directly into your purchase order.
Product Specifications
| Parameter | Specification |
|---|---|
| Product | helical / spiral springs to customer drawing |
| Wire grade | 302 / 304 / 316 stainless spring wire |
| Wire diameter | 0.15-12 mm |
| Checked dimensions | wire dia, coil OD/ID, free length, coils count |
| Functional check | load (or torque) at stated working length |
| Documentation | 3.1 MTC for wire lot + batch inspection report |
The Sampling Logic
Checking every spring in a batch of tens of thousands adds cost without adding much protection. A sampling plan gives the same statistical confidence at a fraction of the effort. Unless the customer specifies otherwise, we inspect per the general inspection level II of ISO 2859-1 (equivalent to ANSI/ASQ Z1.4), with an AQL of 2.5 for dimensional characteristics and 1.5 for the functional load check.
- Sample size scales with batch size - for a 10,000-piece batch, level II calls for 200 pieces on the main table.
- Acceptance numbers are fixed by the plan in advance, so pass/fail is not negotiated after the fact.
- Critical dimensions (wire diameter, coil diameter) can be tightened to AQL 1.0 on request.
- 100 percent inspection is available for safety-critical parts, at agreed cost.
What Gets Measured
- Wire diameter with calibrated micrometer, against the tolerance class ordered.
- Coil outside diameter, inside diameter and free length with gauges or optical measurement.
- Load at a stated deflection (or torque at angle), on a calibrated spring tester, on sampled pieces.
- Surface condition: no cracks, no burrs on ground ends, finish as specified.
When a Batch Fails
If the sample fails, the batch is rejected under the plan. Options are then agreed in advance, not improvised: 100 percent screening of the batch with the defect mode removed, re-grading, or scrap with replacement production. The inspection report states what was found, so both sides work from the same numbers.
Applications
- Valve, switch and actuator springs supplied against drawing
- OEM production parts with formal incoming inspection
- Aftermarket and MRO spring replacement programs
- Any custom spring where batch traceability is required
Product Advantages
- Written sampling plan agreed before production starts
- Calibrated load testing on sampled springs of every batch
- 3.1 MTC for the incoming wire plus batch inspection report
- Defined non-conformance procedure - no silent rework
Quality Control
Gauges and testers are calibrated on schedule, and results are recorded per batch. On request we can work to your own inspection standard - simply attach it to the drawing.
Selection and Ordering Notes
- Send the drawing with dimensions, tolerances and working loads.
- State the inspection standard and AQL you require, or accept ours.
- Indicate whether 100 percent inspection is needed.
- Confirm the deflection (or angle) at which load must be verified.
- Request the batch inspection report with each shipment.
