Using the device – FRITSCH PULVERISETTE 13 premium line User Manual

Page 30

Precise setting of the zero gap. The disks may under no circum-

stances touch each other during the grinding. The local heating

promptly causes tension fissures at the circumference. These fis-

sures appear very quickly and are easily detected.

Local heating can also occur if you fill in so much material that a

comminution of a bed of material takes place constantly on the

outer edges of the grinding disk (grinding gap completely filled

with sample material). This leads to tension fissures at the grinding

disk's circumference and even its breaking.

The hardness of the zirconium oxide grinding disk is 8.5 Mohs

(HV1350). No harder sample material may be comminuted (max-

imum Mohs hardness of 7), because this causes the outer edges of

the grinding disk to break.

Proceed very cautiously when grinding with zirconium oxide

grinding disks. You should pre-crush the grinding stock in a first

pass with a larger gap width, before achieving the desired fineness

with the smallest gap in a second pass. Proceed in the same way if

no information about the grindability of your material is available.

(If necessary, carry out a preliminary test with small sample quan-

tities). The grinding disks have a progressing breakage geometry.

Rough comminution takes place in the inner area and fine commi-

nution takes place in the outer area of the grinding disk. The stress

is greatest in the area of the fine comminution. The described

breakage could occur here with very hard sample materials.

The adhesive used to glue the fastening bolts into the zirconium

oxide grinding disks has a temperature resistance of up to 80 °C.

The grinding disks should therefore not be heated to above 80 °C

so that a firm seat in the mount is ensured.

Please observe the operating instructions concerning the

mounting and removing of the grinding disks. Ä Chapter 9.2

NOTICE!
Fritsch GmbH guarantees that it delivers zirconium oxide

grinding disks of only the utmost quality.
Used grinding disks that are cracked at the circumference,

chipped or completely broken cannot be recognised for

claims.

Using the device

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