FRITSCH PULVERISETTE 6 classic line - Manual (Page 28)

CAUTION!
The grinding element is subject to normal wear when used.
Before every grinding operation, check the wall thickness of
the grinding bowls. In the event of severe wear, replace the
grinding bowl. If this is not done, the prevailing high centri-
fugal forces during grinding may cause the grinding balls to
penetrate the bowl's wall and damage the mill. Failure to
observe this will render void the guarantee and release us
from liability for any resulting damage to the device or per-
sonal injury.
The hardness and density (specific weight) of the grinding bowl and
grinding balls used must be greater than that of the material used to pre-
vent excessive wear by abrasion.
Material
(bowl and balls)
Main components of
the material
Density in g/cm 3
High density means
high impact energy!
Abrasion resistance Use for grinding
stock
Agate (99.9% SiO
2
) 2.65 Good Soft to medium-hard
samples
Silicon nitride (90% Si
3
N
4
) 3.25 Extremely good Abrasive samples,
metal-free grinding
Sintered corundum (99.7% Al
2
O
3
) 3.9 Fairly good Medium-hard,
fibrous samples
Zirconium oxide (96,2% ZrO
2
) 5.7 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
Tungsten carbide (93% WC+6% Co) 14.9 Very good Hard, abrasive sam-
ples
The grinding bowls and grinding balls made of zirconium oxide are
resistant to acids - apart from hydrofluoric acid.
Normally choose a grinding bowl and grinding balls that are made of the
same material.
Using the device
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