GB/T 24608-2023Inspection rules for rolling bearings and commercial parts (English PDF)

Foreword

This document was issued on 28 December 2023 by the State Administration for Market Regulation; Standardization Administration of the PRC and takes effect on 1 April 2024.

It is a GB/T standard: recommended rather than compulsory, but it is the text a Chinese reviewer applies when assessing a submission.

1 Scope

GB/T 24608-2023 governs how a lot of rolling bearings is accepted or rejected: general-purpose bearings together with the commercial parts sold on their own, meaning steel balls, ceramic balls, tapered, cylindrical, spherical and needle rollers, and bearing accessories. The inspection requirements sort the characteristics into key items and the rest, and say for each what is sampled and how it is judged. The sampling and determination methods follow, built on the attribute sampling scheme of GB/T 2828.1 with its acceptance numbers, and a further clause covers supervision inspection, where a quality level is chosen and product already in circulation is checked rather than a consignment at the point of delivery. The symbols and terms clauses tie the vocabulary back to the general bearing standards, so that a purchase specification and an inspection report mean the same thing by the same word. Bearings fail as a population rather than one at a time, and inspecting every ball or roller in a batch is not affordable, so the whole commercial relationship rests on a sampling plan agreed before the goods move. For bearing manufacturers, for the ball and roller suppliers who feed them, and for purchasers and inspection bodies setting up incoming or supervisory checks.

This document specifies the inspection rules for general-purpose rolling bearings and

their commercial parts (steel balls, ceramic balls, tapered rollers, cylindrical rollers,

spherical rollers, needle rollers) and bearing accessories.

This document applies to the inspection, acceptance, and supervision and inspection of

rolling bearings, their commodity parts and bearing accessories by the following

organizations or institutions.

a) the quality department within the supplier organization (the first party);

b) the purchaser or purchasing organization (the second party);

c) inspection and testing agency (the third party).

2 Normative references

The provisions of the following documents constitute the essential clauses of this

document through normative references in this text. Among them, for referenced

documents with dates, only the versions corresponding to the dates are applicable to

this document; for referenced documents without dates, the latest versions (including

all amendments) are applicable to this document.

GB/T 307.1-2017 Rolling bearings - Radial bearings - Geometrical product

specifications (GPS) and tolerance values

GB/T 2828.1-2012 Sampling procedures for inspection by attributes - Part 1.

Sampling schemes indexed by acceptance quality limit (AQL) for lot-by-lot

inspection

GB/T 4199 Rolling bearings - Tolerances - Definitions

GB/T 6930 Rolling bearings - Vocabulary

GB/T 7811-2015 Rolling bearings - Symbols for physical quantities

3 Terms and definitions

The terms and definitions defined in GB/T 4199, GB/T 6930 and GB/T 2828.1-2012

and the following terms and definitions apply to this document.

3.1 supervision and inspection

A means by which government departments control product quality through random

inspections.

3.2 conformity assessment

Demonstration that specified requirements related to a product, process, system, person

or organization are fulfilled.

[Source. GB/T 27000-2023, 3.1, modified]

4 Symbols and abbreviations

The symbols and abbreviations given in GB/T 307.1-2017 and GB/T 7811-2015 and

the following apply to this document.

Ac. Acceptance number

AQL. Acceptance quality limit (expressed as the percent nonconforming or

nonconformities per 100 items)

n. Sample size

p0.Supervision quality level

Re. Rejection number

r. Rejection limit

5 Inspection requirements

5.1 Key items

5.1.1 Sampling and determination of key items of rolling bearings shall be in

accordance with the provisions of Table 1.

5.1.2 The sampling and determination of key items of commercial parts shall be in

accordance with the provisions of Table 2.

5.1.3 The materials and working surfaces of rolling bearings and their commercial parts

and bearing accessories shall comply with the requirements of relevant standards.

5.2 Inspection level

b) specify the acceptance quality limit (AQL) value;

c) select the type of sampling plan;

d) determine the severity of this inspection (normal, tightened or reduced

inspection) based on the previous inspection results and the adjustment and

transfer rules. Normal inspection shall be used at the beginning of the

inspection;

e) submit product lot;

f) check the packing quality and marking;

g) determine the sampling plan;

h) random sampling;

i) testing samples;

j) determine whether to accept or reject the batch based on the number of non-

conforming items in the sample and the acceptance number Ac and rejection

number Re in the sampling plan;

k) acceptable batches;

l) Disposal of unacceptable batches.

6.2 Batch formation

6.2.1 The varieties, models, specifications, materials and process conditions of the

product lots submitted for inspection shall be as similar as possible and the

manufacturing time shall be similar.

6.2.2 The lot size of products submitted for inspection and the method of submission of

each lot may be determined by negotiation between the first party and the second party.

6.3 Sample inspection

6.3.1 Inspect the sample units one by one according to the specified inspection items.

6.3.2 The technical conditions of each item shall be in accordance with the relevant

standards. For items where the technical conditions are not specified in the standards,

they shall be in accordance with the sample drawings or technical documents approved

by the first or second party.

6.4 Determination of acceptable lots and unacceptable lots

6.4.1 Single sampling inspection

Use the single sampling inspection plan table. According to the sample inspection

results, if the number of nonconforming items found in the sample is less than or equal

to the acceptance number, the lot shall be considered acceptable. If the number of

nonconforming items found in the sample is greater than or equal to the rejection

number, the lot shall be considered unacceptable.

6.4.2 Double sampling inspection

Use the double sampling inspection plan table.

The number of samples for the first inspection shall be equal to the first sample size

given in the plan. If the number of nonconforming items found in the first sample is

less than or equal to the first acceptance number, the lot shall be considered acceptable;

if the number of nonconforming items found in the first sample is greater than or equal

to the first rejection number, the lot shall be considered unacceptable.

If the number of nonconforming items found in the first sample is between the first

acceptance number and the first rejection number, the second sample with the sample

size given by the plan shall be inspected and the number of nonconforming items found

in the first sample and the second sample shall be accumulated. If the accumulated

number of nonconforming items is less than or equal to the second acceptance number,

the lot is considered acceptable; if the accumulated number of nonconforming items is

greater than or equal to the second rejection number, the lot is considered unacceptable.

6.5 Disposal of lots

6.5.1 The lot judged as acceptable shall be accepted in its entirety. However, any

nonconforming items found during the inspection process shall be discarded or replaced

with conforming items by the first party.

6.5.2 In principle, the entire lot judged as unacceptable shall be returned to the first

party. The first party shall re-inspect the nonconforming items in the rejected lot,

remove the nonconforming items or replace them with conforming items, and then

submit them to the second party for inspection again.