information cannot be obtained, the sieving time and amplitude must be determined
experimentally.
With the AS 200 control the amplitude is defined as the total lifting height (SH) of the test sieve.
For example, with a set amplitude of 1.2 mm, the test sieve is displaced in the range of -0.6 mm
and +0.6 mm around the zero point (= stationary sieve plate (ST)).
An optimum amplitude has been found, when a state of statistical resonance is being reached
during the sieving process. Then, the particles have the biggest probability of passing, as the
throw time of a particle corresponds to the oscillation period of the test sieve. In this case, the
particle (PA1) will be moved with a different orientation to a different mesh every time the test
sieve (SH) lifts. At too low amplitudes, the particles (PA2) do not lift off high enough from the
sieve mesh fabric, and are therefore not able to orientate freely and move freely over the sieve
mesh fabric. At too high amplitudes, the particles (PA3) are thrown up very high, and thus have
fewer opportunities to compare themselves with the sieve meshes. The best results are
generally achieved with amplitudes from 1.0 to 1.5 mm.
The optimum sieving time is in accordance with DIN 66165 achieved, if less than 0.1 % of the
feed quantity passes the test sieve after one minute of sieving duration. In practice, the
individual test sieves are weighed after the sieving process including the respective particle size
fraction. Then, the sieve stack is sieved again for one minute. The weights of the individual test
sieves of the second weighing must not differ substantially from those of the first weighing.
7.8 Interval
Press the button (H6) to change to the interval operation. The green LED is lit.
Press the button (H6) again, to change back to the continuous operation. The green
LED no longer lights up.
During the interval operation, the sieving process is periodically interrupted for one second. In
interval operation, the interval times (pause times) are included in the displayed process time
(H5). The interval operation can be switched on and off at any time during the sieving process.
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