6.1 For the provisions of 5.1, 5.2 and 5.7.2, the measuring instrument with a precision not less than 0.1mm shall be used for the measurement, and the parts where surface defects may cause measurement errors shall be avoided during the measurement.

6.2  For the provision of 5.3,inspection and arbitration should be according with GB/T 223.1 一 198L GB/T 223. 2—1981, GB/T 223. 3—1988, GB/T 223. 4—1988, GB/T 223. 11—199b GB/T223. 14—2000, GB/T 223. 16—199h GB/T 223.18—1994, GB/T 223.26—1989, GB/T 223, 60—1997, GB/T 223.63—1988. It allowable for testing according to GB/T 5678—1985.

6.3 Preparation of samples with low hardness and micro-structure.

Test samples for the hardness difference and micro-structure may be prepared by wire cutting or electrical discharge machining. The section of the sample shall be perpendicular to the parting surface of the casting ball which producing by grinding steel ball die and pass through the center of the in-gate and the center. The cut surface shall be abraded to at least 1 mm.If the sample is prepared mechanically, the cutting surface shall be ground to at least 2 mm.

6.4  Surface hardness (4.1)and hardness difference (5.4.2) are tested according to GB / T230. Hardness difference shall be tested at intervals of 5mm along the diameter passing through the center of the in-gate.

6.5 The inspection of 5. 5 shall be carried out on the grinding surface specified in 6. 3. The test method was carried out with reference to GB/T 226.

6.6 5.5 and 5.5.1 shall be inspected by naked eye.

6.7 The impact fatigue test life of 5.4.3 drop ball iscarried out according to appendix a in GB / T 17445 -1998.

6.8 For 5.6 the measurement and calculation of broken ball rate and ball consumption are carried out according to Appendix A.