Retsch MM 500 Vario, Manual

Page: 39 / 87

Operating the Device
39
6.3.3 Recommended maximum ball sizes
Grinding jar size Ball size
1.5 ml 5 mm
5 ml 7 mm
10 ml 12 mm
25 ml 15 mm
35 ml 20 mm
50 ml 25 mm
6.3.4 Recommended Grinding Jar Filling
In addition to device settings, the fill level of the grinding jars is crucial for the success of
grinding in the Mixer Mill.
When grinding bulk materials, a grinding jar filling should
consist roughly of one third sample material and one third ball volume. The remaining
third is the empty grinding jar volume that the balls need in order to move. Please pay attention
to the maximum permitted ball size for the material in question.
If an increase in volume or decrease in volume is to be expected during grinding, the sample
volume can be adjusted in line with the range set out in the table. For example in the case of
voluminous sample material such as wool, leaves, grasses etc., an initial material filling of 70
–
80 % is necessary.
The ball filling should comprise 60 % of the grinding jar volume for wet grinding with grinding
balls < 3 mm. As with dry grinding, the sample material should fill one third of the grinding jar
volume. Wet grinding should be conducted in such a way that the mixture of grinding balls,
sample material and liquid achieves a viscous consistency. If the mixture is too viscous, the
grinding balls do not move sufficiently. If it is not viscous enough, the grinding results will be
poorer and there will be increased wear to the grinding balls and grinding jars.
Dry grinding
Recommended number of grinding balls
Grinding jar
size
Sample volume Max. feed size Ø
5 mm
Ø
7 mm
Ø
10 mm
Ø
12 mm
1.5 ml 0.2
–0.5 ml
1 mm
1 - 2 - -
-
5 ml 0.5
–2 ml
2 mm
5 - 6 1-2 -
-
10 ml 2
–4 ml
4 mm
17 - 20 9 - 12 1 - 2 1 - 2
25 ml 4
–10 ml
6 mm
35 - 40 16 - 20 5 - 6 2 - 4
35 ml 6-15 ml 6 mm
55 - 60 25 - 30 6 - 9 4 - 6
50 ml 8-20 ml 8 mm
80 - 90 45 - 50 12 - 14 6 - 8