PRODUCT

Ball diameter nominal

mm

20

25

30

35

40

50

60

70

80

90

100

110

125

130

140

Ball weight nominal

g

33

64

111

176

263

514

888

1410

2104

2996

4110

5471

8028

9030

11279

Number of balls per ton

nr/t

30.303

15.625

9.009

5.682

3.802

1.946

1.126

709

475

334

243

183

125

111

89

Quality Range

Quality

Full Hardness

Intermedaite Hardness

Reduced Hardness

Hardness Rockwell C (HRC)

Hardness Rockwell C (HRC)

60 – 65 high abrasion

58 – 62 combining impact and abrasion resistance

55 – 58 high impact

Quality Guarantee

Maximum two (2) percent in normal and correct mill operating conditions.

Replacement free of charge of any quantity in excess of two (2) percent found to be broken for causes not related to incorrect mill operating conditions.

This guarantee also applies to any misshapen new balls supplied. 

For normal and correct operating conditions it is meant that the mill should not be operated with such a low level of material to be ground that severe ball-to-ball contact occurs without the cushioning effect normally given by the material.

Severe ball-to-ball contact can be generally detected by the formation of stress induced martensite on the surface of the balls and/or by the increase of hardness, with possible formation of cracks, on the exposed surface layers of the fragments.