How DW Bearing Tests Needle Bearings: ISO/TS 16949 SPC Data from Our QC Lab

time 2026-05-20

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Published: May 20, 2026 | Audience: Quality engineers, OEM SQE, procurement teams evaluating suppliers

TL;DR: DW Bearing operates an ISO/TS 16949-compliant quality control lab in our Suzhou plant. This article walks through our actual inspection equipment, SPC control limits, Cpk targets, and lot-acceptance protocols for HK, BK, NK, and K series needle roller bearings — the same data we provide to Bosch, Delphi, and BYD on every shipment.

1. Inspection Equipment in the DW QC Lab

Equipment	Brand / Model	Use	Measurement Range / Resolution
CMM (Coordinate Measuring Machine)	Zeiss CONTURA G2	Outer / inner diameter, width, raceway profile	0.5 µm resolution
Roundness Tester	Taylor Hobson Talyrond 365	Outer cup roundness, raceway form	0.05 µm resolution
Surface Roughness Tester	Mitutoyo SJ-411	Raceway Ra, Rz, Rmax	0.001 µm resolution
Rockwell Hardness Tester	Wilson Rockwell 574T	HRC core / surface hardness	HRC 0.1 division
Metallurgical Microscope	Olympus GX53 (200-1000x)	Microstructure, decarb depth, carbide network	200-1000x
Endurance Test Rig	DW-built (10 spindle)	Accelerated L10 life test	0-15,000 RPM, 0-50 kN load

2. Inspection Sampling Plan (per ISO/TS 16949)

Each production lot follows AQL 0.65 (normal inspection per ISO 2859-1):

Lot size 501-1,200: sample 80 pcs, accept 1 defect max
Lot size 1,201-3,200: sample 125 pcs, accept 2 defects max
Lot size 3,201-10,000: sample 200 pcs, accept 3 defects max
Hardness: 5 pieces per lot (HRC 60-65 acceptance)
Microstructure: 1 piece per lot, photographed and archived for 7 years

3. SPC Control Limits for HK1010

Example SPC data from one production lot of HK1010 (boundary Fw 10 x D 14 x C 10 mm), n=200 per QC plan:

Parameter	Spec	Mean	StdDev	Cpk
Outer diameter D	14.000 -0/+0.010	14.0042	0.0011	1.78
Inner diameter Fw	10.000 -0/-0.010	9.9961	0.0012	1.69
Width C	10.000 ±0.100	10.004	0.012	2.61
Raceway Ra (µm)	<0.20	0.085	0.018	2.12
Roundness (µm)	<3.0	1.2	0.35	1.71
Hardness HRC	60-65	62.4	0.65	1.33

Acceptance: dimensional Cpk ≥ 1.33 (IATF 16949 PPAP), surface and hardness Cpk ≥ 1.67. Our process consistently exceeds these.

4. Lot Traceability

Every shipment includes: Certificate of Analysis (CoA), material mill certificate to steel heat number, heat treatment chart, photographic microstructure report (case + core), sample inspection log. Records archived 7 years per IATF 16949 4.2.4.

5. Endurance Testing (L10 Validation)

For new part numbers or design changes: 10-spindle test rig, 5,000-10,000 RPM, load 30-50% of Cr basic dynamic rating, continuous run until first spalling or 500 hours. Data archived for PPAP submissions.

6. FAQ

Q1: Do you provide CMM dimensional reports per shipment?
Yes for automotive PPAP customers. Standard CoA includes summary statistics + min/max from sample.

Q2: What is your acceptable defect rate?
Targets <100 PPM dimensional, <500 PPM cosmetic. 2025 trailing twelve-month: 38 PPM across all automotive OEMs.

Q3: Can I audit DW QC lab?
Yes. We host customer SQE audits annually. Schedule via [email protected].

Q4: ISIR turnaround?
5 working days from tooling-out to ISIR. PPAP Level 3 documentation: 10 days.