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DIN 51813 Prüfung von Schmierstoffen;
Bestimmung des Gehaltes an festen Stoffen in
Schmierfetten; Teilchengr??en über 25 μm, 1989.
润滑脂固体物质含量
Solid particles in greases cause severe problem during
the operation of lubricated units. They influence the
noise behaviour of ball bearings and enhance the wear
rate of interacting components. Solid matter content in
lubricating greases is given in DIN 51813 . The
method employing the hydraulic grease press
we describe here is applicable to greases not containing
any solid lubricants. Operating pressure of hydraulic
grease press is up to 150 bar, and the test load at the
piston is ca. 60 – 70 kN.
Mean quantity 500 g of a grease sample is pressed
through the test sieve (Fig. 5). The squeezed grease is
dissolved in a solvent mixture and in acetic acid and
then filtered. After washing out and drying the filter
crucible, a mass difference is used to determine the
fraction of solid particles contaminating the grease.
Test sieve with a mesh size of 0.025 mm is made of
stainless steel, e.g. according to DIN 4188, and could be
214 ? VOL. 43, No 3, 2015 FME Transactions
used not more than for two tests. Base fabric on the
sieve bottom is of the same steel, whereas its mesh size
is 0.5 mm (Fig. 5).
Precision of the method is characterised by
repeatability and comparability as it is shown in the
following Table 1.
Table 1. Repeatability and comparability of the test method
(mass fraction in mg/kg)
Solid matter content Repeatability Comparability
< 10.0 5.0 10.0
≥ 10.0 7.5 15.0
Some additional controls integrated into the hydraulic
grease press make also possible testing the filterability of
greases. These include adjustment of the flow rate at the
test sieve and the pressure within the grease cartridge.
The adjustment range of both characteristics is based on
the range of parameters prevailing in filters. Results of
such tests show user whether grease is suitable for an
application. Adjustable flow rate at the test sieve ranges
from 0.5 to 1.5 m/min; adjustable maximum of filtration
pressure is 60 bar, whereas pressure measurements at the
test sieve lie in the range from 0 to 60 bar.
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