Roundness measurement
Roundness measurement against the method and acceptance limits specified for your part.
BOYA INDUSTRIES / PRECISION & SUPPLY
Quality & Inspection
Steel ball inspection methods, acceptance criteria and quality documentation for material, dimensions, roundness and hardness.
DEFINE. CHECK. DOCUMENT.
Quality begins with an agreed specification.
A grade label alone does not define every acceptance requirement. We coordinate material, dimensions, inspection methods and the documentation requested by your team.
- Review material and dimensional requirements before quotation.
- Agree sampling, measurement methods and reporting needs.
- Discuss material records and batch identification for your order.
INSPECTION EQUIPMENT
Inspection you can see.
Measurement methods, sampling plans and acceptance limits are defined by the product specification.
Metallographic inspection
Microstructure examination with a metallographic microscope, according to the agreed inspection specification.
Hardness testing
Hardness testing equipment. Required scale, test method and limits should be stated in your enquiry.
Dimensional inspection
Precision length measurement equipment for dimensional checks. Measurement capability is confirmed per requirement.
Crushing load testing
Crushing load testing with the test conditions and reporting requirements agreed before supply.
Profile measurement
Profile measurement for reviewing the surface contour against the agreed specification.
DOCUMENTATION CHECKLIST
Specify the records you need.
Tell us which records your team needs for supplier approval and incoming inspection.
01
Material documentation
State the material designation, governing standard and the material document your team needs for acceptance.
02
Inspection records
List the characteristics to be checked, acceptance limits, test methods and any required report format or sampling plan.
03
Batch identification
Explain how the part number, drawing revision and lot identifier should appear on labels and accompanying records.
Add document requirements to your RFQ
List document names and any required format in Additional requirements. Document scope and availability are agreed with the quotation.
MANUFACTURING PARTNER CERTIFICATION
Quality management certifications
Our manufacturing partner holds ISO 9001 and IATF 16949 certifications. BOYA Industries manages orders, overseas sales and quality coordination.
ISO 9001:2015
Manufacturing of metal balls and their raw materials, steel wires and ball billets; manufacturing of non-metallic balls (ceramic balls).
- Certificate holder
- Manufacturing partner
- Certification body
- Beijing ZhongRunXing Certification Co., Ltd.
- Issued
- 2024-07-03
- Certificate expiry
- 2027-07-02
IATF 16949:2016
Production of bearing steel balls.
- Certificate holder
- Manufacturing partner
- Certification body
- AENOR
- Issued
- 2025-03-17
- Certificate expiry
- 2028-03-16
- Exclusion
- Product design
G10 lot inspection results
Inspection records for three featured sizes of GCr15 chrome steel bearing balls.
5/32″≈3.9688 mm
- Surface roughness (Ra)
- 0.006 μm0.005 μm0.006 μm
- Deviation from spherical form
- 0.036–0.076 μm
- Hardness
- 63.2–64.0 HRC
3/16″4.7625 mm
- Surface roughness (Ra)
- 0.006 μm0.005 μm0.005 μm
- Deviation from spherical form
- 0.071–0.130 μm
- Hardness
- 64.7–65.4 HRC
1/4″6.35 mm
- Surface roughness (Ra)
- 0.005 μm0.005 μm0.006 μm
- Deviation from spherical form
- 0.025–0.044 μm
- Hardness
- 64.4–65.4 HRC
5/32″ · 3.9688 mmFull inspection results
| Inspection item | Inspection requirement | Recorded result |
|---|---|---|
| Ball gauge (lot size deviation) | Per process requirements | ±0 (+0.2) μm |
| Surface quality | JB/T 10861-2008 · G10 | Pass |
| Ball diameter variation | ≤0.25 μm | 0.1 μm |
| Ball lot diameter variation | ≤0.5 μm | 0.05 μm |
| Deviation from spherical form | ≤0.25 μm | 0.059 μm0.036 μm0.062 μm0.076 μm0.066 μm |
| Surface roughness (Ra) | ≤0.02 μm | 0.006 μm0.005 μm0.006 μm |
| Single-ball vibration | ≤31 dB | 29.1 dB28.7 dB29.4 dB28.6 dB28.5 dB29.5 dB28.7 dB28.3 dB29.3 dB28.2 dB |
| Tempered martensitic core structure (rating) | 1–4级 | 33333 |
| Hardness | 61–66 HRC | 64.0 HRC64.0 HRC64.0 HRC63.2 HRC63.2 HRC |
| Crushing load | ≥8.43 kN | 16.56 kN |
Inspection references: GB/T 308.1-2013 · GB/T 34891-2017 · JB/T 7363-2023
Discuss your inspection requirements ↗3/16″ · 4.7625 mmFull inspection results
| Inspection item | Inspection requirement | Recorded result |
|---|---|---|
| Ball gauge (lot size deviation) | Per process requirements | ±0 (±0) μm |
| Surface quality | JB/T 10861-2008 · G10 | Pass |
| Ball diameter variation | ≤0.25 μm | 0.1 μm |
| Ball lot diameter variation | ≤0.5 μm | 0.05 μm |
| Deviation from spherical form | ≤0.25 μm | 0.071 μm0.120 μm0.085 μm0.130 μm0.091 μm |
| Surface roughness (Ra) | ≤0.02 μm | 0.006 μm0.005 μm0.005 μm |
| Single-ball vibration | ≤31 dB | 24.7 dB26.1 dB25.0 dB24.6 dB24.9 dB25.2 dB26.0 dB27.1 dB25.0 dB27.0 dB |
| Tempered martensitic core structure (rating) | 1–4级 | 33333 |
| Hardness | 61–66 HRC | 65.1 HRC65.4 HRC65.1 HRC64.7 HRC64.8 HRC |
| Crushing load | ≥12.05 kN | 23.11 kN |
Inspection references: GB/T 308.1-2013 · GB/T 34891-2017 · JB/T 7363-2023
Discuss your inspection requirements ↗1/4″ · 6.35 mmFull inspection results
| Inspection item | Inspection requirement | Recorded result |
|---|---|---|
| Ball gauge (lot size deviation) | Per process requirements | ±0 (+0.4) μm |
| Surface quality | JB/T 10861-2008 · G10 | Pass |
| Ball diameter variation | ≤0.25 μm | 0.05 μm |
| Ball lot diameter variation | ≤0.5 μm | 0.05 μm |
| Deviation from spherical form | ≤0.25 μm | 0.042 μm0.030 μm0.044 μm0.025 μm0.032 μm |
| Surface roughness (Ra) | ≤0.02 μm | 0.005 μm0.005 μm0.006 μm |
| Single-ball vibration | ≤31 dB | 26.4 dB27.2 dB27.3 dB25.2 dB27.3 dB |
| Tempered martensitic core structure (rating) | 1–4级 | 33333 |
| Hardness | 61–66 HRC | 65.4 HRC64.9 HRC64.4 HRC64.6 HRC64.6 HRC |
| Crushing load | ≥21.27 kN | 42.86 kN |
Inspection references: GB/T 308.1-2013 · GB/T 34891-2017 · JB/T 7363-2023
Discuss your inspection requirements ↗Inspection methods & equipment
Our manufacturing partner measures surface roughness Ra using a SURFCOM NEX 001SD2-12 instrument. The inspection methods for the displayed lots are listed below.
View inspection methods
- Diameter & dimensional consistency
- D051, 0.1 μm torsion-spring comparator
- Deviation from spherical form
- Cylindricity measuring instrument
- Surface roughness (Ra)
- Profilometer · SURFCOM NEX 001SD2-12
- Surface quality
- 100× microscope
- Hardness
- Rockwell hardness tester
- Single-ball vibration
- Vibration tester
- Tempered martensitic core structure (rating)
- 500× metallographic microscope
- Crushing load
- Crushing-load testing machine
Lot-to-heat traceability
Production records link the displayed G10 finished-ball lots to their raw-material heat numbers. BOYA coordinates inspection and quality documentation requirements for your order.
- Raw-material heat number
- Production records
- Finished-ball lot
G5 grade limits
G5 is available on request. Specify the diameter and acceptance requirements in your enquiry.
| Inspection item | G5 specification limit |
|---|---|
| Ball diameter variation | ≤0.13 μm |
| Deviation from spherical form | ≤0.13 μm |
| Ball lot diameter variation | ≤0.25 μm |
| Surface roughness (Ra) | Ra ≤0.014 μm |