FRITSCH PULVERISETTE 23 - Manual (Page 19)

6 Using the planetary mill
6.1 Choice of grinding bowls and grinding balls
CAUTION!
If the grinding elements used are not genuine accessories,
we assume no guarantee and exclude all liability for
damage to the device or for personal injury.
To prevent excessive wear caused by abrasion, the hardness and density
(specific weight) of the grinding bowl and grinding balls used must be
greater than that of the material used.
Material
(bowl and balls)
Main components of
the material
Density in g/cm 3 Abrasion resistance Use for grinding
stock
Zirconium oxide (95% ZrO
2
) 5.9 Very good Fibrous, abrasive
samples
Stainless steel Bowl:
(17-19% Cr + 8-10%
Ni)
Balls:
(12.5-14.5% Cr + 1%
Ni)
7.8 Fairly good Medium-hard, brittle
samples
Tempered steel Bowl: (11-12% Cr)
Balls: (1.0-1.65% Cr) 7.9 Good Hard, brittle samples
PTFE 2,2 Fairly good Soft, brittle samples
It is recommended to choose a grinding bowl and grinding balls that are
made of the same material.
6.1.1 Size of the grinding balls
Type of feed material Ball diameter
Hard samples with a maximum
size of 2-5 mm
15 mm
Fine material (0.5 mm) 10 mm / 5 mm
Homogenisation of dry or liquid
samples
10 mm / 5 mm
Using the planetary mill
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