4.1 Chrome alloy cast iron grinding balls are divided into 7 grades according to the chrome content. Nodular cast iron grinding balls are divided into two grades according to the matrix structure, I. E. Bainite ductile cast iron grinding balls and Martensite ductile cast iron grinding balls.

4.2 Cast grinding balls are sized to their nominal diameter. Tolerances for grinding ball diameters are shown in Table 1

                                          Tolerance table for diameter of cast grinding ball (mm)

Diameter Ф	Ф ≤30	30<Ф≤60	60<Ф≤80	80<Ф≤100	Ф>100
Tolerance	+1.0 -1.0	+1.5 -1.0	+2.0 -1.0	+2.5 -1.1	+3.0 -1.0

4.3 Representative methods for the casting grinding balls grades

4.3.1 Reference to GB / T 5612 for cast iron grades.

4.3.2 Using ZQ represents Casting grinding balls; QT represents ductile cast iron

4.3.3 The grade of chrome alloy cast iron specified in this standard only specifies the main addition alloy chrome element and its content. In accordance with the provisions of GB/T 5612, alloy element content greater than or equal to 1% , expressed in integers

4.3.4 Ductile cast iron grinding balls are divided into B and M, which represent Bainite ductile iron grinding balls and Martensite ductile iron grinding balls respectively.

4.3.5 Chrome alloy cast iron grinding balls shows like following, using ZQCr12 as the example.

                         ZQ  Cr  12

                   :      :     :

                            :      :     :

                            :      :     :.. .. .. .. ..Nominal percentage of chrome

                            :      :.. .. .. … .. .. .. ..Element of the Chrome

                            :.. .. .. .. .. .. .. .. .. .. .. … Cast iron grinding balls

 

4.3.6 Ductile cast iron grinding balls shows like following, grade number: ZQQTB

                       ZQ   QT  B

                         :        :      :

                         :        :      :

                         :        :      :… .. .. .. ..The Matrix State,mainly is the Bainite

                         :        : .. .. .. .. .. .. .. .. .. Short for Ductile cast iron

                         :.. . . . . . . . . . . . . . . . . . . . .. Cast iron grinding balls

 

4.4 Representation of code for casting grinding ball

Adding diameter after the representation of code for grinding balls separating by ‘_’, for example dia100mm grinding balls, grade no. is ZQCr12, then can show as ZQCr12-100.