FRITSCH PULVERISETTE 1, Model I classic line - Manual (Page 23)

Page 21
5.3.4 Final size
The obtainable final size depends upon the selected gap setting (about 1 mm to 15
mm). The gap setting determines only one dimension of the crushed material. This
means, that for instance flaky shaped material can have a completely different size
in another dimension compared with the set gap. If this should be the case, in many
cases a second pass of he crushed material through the crusher will considerably
reduce the amount of the grains being larger in one dimension.
At the smallest gap setting, the average grain size (d
50
) of the crushed material is
approximately 2 mm.
5.3.5 Setting of the link plate
Normally, the link plate (23) which is hold by the link pin (6) is positioned in the
lower position.
In some cases it may be advantageous to crush materials having positioned the link
plate and link pin in the upper position.
Because of the fact that such a position reduces the gap opening between the jaws,
the particle size distribution of the crushed material is narrower respectively the
particle size is more uniform. However, this leads to a slightly longer crushing time.
This position can not be selected for materials like slades, coal, coke and
somewhat sticky materials. It can only be selected for easy to break/crush samples.
In some cases it can be of advantage to pre-crush the material in the lower position
and to finally crush it to a small size in the upper position.