Standard of the Chromium Alloy Cast Grinding Balls in Building Materials Industry (6)

7.Inspection Provision

7.1 The ball shall be inspected by the quality inspection department of the manufacturer.

7.2 Inspection classification: inspection is divided into factory inspection and type inspection.

7.3 The inspection items are diameter deviation (1), shape deviation(5.2), chemical composition (5.3), surface hardness (5.4.1), appearance quality (5.7.1,5.7.2).

7.4 About the provision of 5.1,5.2, 5.7.2, 5.7.1, according to GB/T 2828 – 1987.

7.4.1 The sampling scheme was carried out according to table 3 of GB/T 2828-1987.

7.4.2 The inspection level shall be the general inspection level as shown in table 2 of GB/T 2828 — 1987ǁ

7.4.3 The classification of unqualifiedproducts and the level of qualified quality are shown in Table 5

Table 5

Qualitative characteristics

Unqualified categoryQualified quality level

5.7.1 provision



5.1 and 5.2 provision



5. 7. 2 provisionC


7.5  3 The chemical composition should be checked furnace by furnace, one experiment should be randomly selected from each furnace to be checked, if the test is not qualified, it should be rechecked, if there are still unqualified, the furnace is not qualified

7.6  For the inspection of surface hardness of 5.4.1 cast balls, non-continuous heat treatment furnaces shall be sampled from different positions of each furnace in not less than five: continuous heat treatment furnaces. According to each working class random sampling, the number of not less than five; after inspection, if there is a casting ball unqualified, should be allowed to take double casting ball for re-inspection, if there is still a casting ball unqualified, the batch is unqualified, if the hardness is not qualified, repeated Heat treatment is allowed.

7.7  For 5.4.2 and 5.5 inspection, the casting balls of the same brand and the same process are randomly selected for inspection every half month of continuous production. If the inspection is not up to standard, double inspection shall be made in the lot. If there is still a nonconformity, the lot is considered nonconforming.

7.8  Drop ball impact fatigue life test according to GB / T17445-1998 Appendix A, random sampling in qualified products, the same brand of the same process produced by the cast ball should be tested at least once a month. The results of drop ball impact fatigue test shall conform to the requirements of 5.4.3.

7.9 Type checking

In any of the following circumstances, type testing shall be conducted in accordance with all the technical requirements specified in this standard.

A) When new products are trial-produced;

B) Production process has a major change, may affect the quality of products;

C) Inspection shall be carried out at least once every six months after mass production:

D) long-term suspension of production, the resumption of production;

E)When there is obvious difference between the ex-factory inspection and the previous type inspection;

F) when the State Quality Supervision Agency makes a request for type inspection.

8.Marking, packaging, transportation and storage

8.1 Packing

The ball shall be packed in safe (iron drum or woven bag) or in bulk.

8.2 Mark

Each batch of products should be accompanied by a product certificate (or quality guarantee certificate) stamped by the inspection department, indicating:

A) the name of the supplier;

B) trade mark;

C) the name, code and Standard Number of the cast ball;

D) the lot number of the product;

E) date of manufacture.

8.3 Transportation

The mode of shipment of cast balls shall be agreed upon by the parties.

8.4  Storage

The cast balls shall be stored separately according to the type, brand and specification of the balls. Acid, alkali and water erosion should be prevented.