Why 100% inspection
For shaft parts with assembly or safety requirements, the statistical risk of sampling is often unacceptable — a single out-of-tolerance part reaching a customer's line costs far more than the inspection time. For Ø5–200 mm shafts held to around 0.01 mm, we offer 100% inspection on both length and outside diameter.
Gauge selection
| Characteristic | Gauge | Notes |
|---|---|---|
| Length / shoulder length | Digital calliper, height gauge | Fast, good for batch screening |
| OD (with a reading) | Outside micrometer | Gives an actual value for records and traceability |
| OD (go/no-go) | Ring gauge | Second-level pass/fail, ideal for high-volume 100% check |
| ID | Internal gauges, plug gauge | For bored parts |
| Threads | Thread gauges | Go / no-go |
| Complex profiles | Profile projector | First article and dispute resolution |
The value of a ring gauge is that it converts a measurement into a decision: the go end must pass, the no-go end must not. It is fast, simple, and independent of how an operator reads a scale. What it does not give you is a number — so it is normally paired with a micrometer: record actual values on the first article and during patrol inspection, then verify every piece with the ring gauge during production.
Takt time
A single 8-hour shift producing 2,000 pieces allows about 14.4 seconds per part. The key is to run the two checks in parallel rather than in series:
- Length checked with a calliper at the front of the workstation
- OD checked with the ring gauge piece by piece
- Every hour or every 200 pieces, measure 5–10 parts with a micrometer and record the values to catch process drift
With this arrangement the marginal time for 100% inspection comes mainly from loading and unloading, not from measuring.
Records and traceability
100% inspection is not complete without records. We keep:
- First article inspection record with actual values on critical dimensions
- Patrol inspection log — time, measured value, operator
- Pre-shipment inspection report — quantity, batch, inspection method
Customers with export or system requirements can also receive full dimensional reports and material certificates. These should be raised at quotation stage so inspection time can be planned in.
When sampling is enough
Where critical dimensions are guaranteed by a stable process and the customer accepts sampling, a sampling plan is cheaper. The choice depends on the consequence of failure, the customer's acceptance criteria and the batch size. Agreeing on those three things up front is far cheaper than dealing with it later.