Home › Resources › Incoming inspection

Incoming Bearing Inspection — What to Check and How Many

You cannot inspect a bearing into quality, but you can catch a wrong or damaged lot before it reaches the line. This is what to check, how many pieces, and what to write down.

VisualDimensionalSamplingRecords

Short answer. Check four things: the paperwork against the order, the packaging and marking, a visual inspection of the sample, and the critical dimensions. Sample to ISO 2859-1 at the AQL on the purchase order — commonly 1.0 — and record the lot number, the sample size and the measured values, because a claim without that record is a conversation.

At a glance

What this checklist covers and who it is for.

Paperwork	Order vs packing list vs certificate vs marking on the box
Visual	Rust, seal damage, cage damage, marking legibility, grease presence
Dimensional	Bore, OD, width, runout, clearance on the sample
Sampling	ISO 2859-1, AQL as agreed — 1.0 unless specified
Record	Lot number, sample size, measured values, inspector, date
Rejection	Quarantine the lot, photograph, notify within the claim window

Step 1 — Paperwork before unpacking

Five minutes, catches the most common error.

Packing list matches the purchase order: model, quantity, brand.
Certificate of conformity present and quoting the same lot number as the packing list.
Box marking matches the certificate: model, suffix, brand, quantity.
Any 3.1 or FAI document present if it was ordered — chasing it later is slower.

Step 2 — Visual inspection

Look at the sample, not at the top of the carton.

Rust or staining on rings, raceways or balls — condensation in transit is common.
Seal or shield damage: lips torn, shields deformed, one seal missing.
Cage damage: cracks, deformed pockets, rivets loose.
Marking: brand and model legible on the ring, not just on the box.
Grease: present, evenly distributed, no separation or hardening.
Rotation: smooth and quiet by hand, no notchiness, no axial play beyond the clearance.

Step 3 — Dimensional check

Three dimensions plus two functional checks.

The five measurements that matter most

Instrument and typical acceptance basis.

Check	Instrument	Acceptance basis	Record
Bore diameter	Bore gauge	ISO 492 for the class ordered	Actual value
Outside diameter	Micrometer	ISO 492 for the class ordered	Actual value
Width	Micrometer	ISO 492 for the class ordered	Actual value
Radial runout	V-block + dial gauge	Per the precision class	Max reading
Internal clearance	Clearance gauge	Per the C-class ordered	Actual value

Step 4 — Sampling

How many pieces, decided in advance.

Use the AQL on the purchase order; ISO 2859-1 at AQL 1.0 normal inspection is the usual default. For a lot of 501–1,200 pieces that means 80 pieces sampled, accept on 2, reject on 3. Recording the sample size is what makes the result defensible.

Quick sampling reference, AQL 1.0

Full tables are in ISO 2859-1; this covers the common lot sizes.

Lot size	Sample	Accept	Reject
26–50	8	0	1
51–90	13	0	1
91–150	20	0	1
151–280	32	1	2
281–500	50	1	2
501–1,200	80	2	3

Step 5 — Record and decide

One page per lot.

Lot number, quantity, supplier, date received, inspector.
Sample size, AQL, measured values and the pass/fail result.
Photographs of any defect, with a scale reference.
Decision: accept, accept with concession, or quarantine and claim.

Quarantine first. A defective lot goes into a marked area with the paperwork attached, not back on the shelf. Most claim disputes are lost because the parts were mixed with good stock before anyone looked.

Frequently asked questions

Do I have to inspect every delivery?

No. Inspect the first lot from a supplier fully, then reduce to a skip-lot or reduced-inspection plan while the supplier performs. Return to full inspection after any rejection.

What if the certificate is missing?

Quarantine the lot until it arrives, and record the delay. A missing certificate is a documentation non-conformity, not a reason to reject good parts — but it must be closed before the parts are used.

How do I check internal clearance without a clearance gauge?

Measure the displacement of the outer ring relative to the inner under a defined axial load with a dial gauge. It is less precise than a dedicated gauge but adequate for a comparison against the specified class.

What is the most common incoming defect?

In our experience, wrong suffix rather than wrong size: the bore and OD are right, the seal or clearance is not. That is why the paperwork check comes before the dimensional check.

Want this checked against a real list?

Send the BOM, the inspection plan or the failure photos. We will run through the same checklist and send back the gaps.

Send your model list Browse the catalogue