Volume 15, Issue 2 (March 1987)
An Experimental Sieving Machine
Sieving by hand is tedious but can be the most consistent of the available methods of sieve analysis. Segregation, particularly of materials having irregularly shaped particles, produced by generally available machines is seldom completely in agreement with hand sieving results. Moreover, gradings produced by different machines often differ significantly from one another.
Sieving machines, generally, are vibratory at low amplitude, with overdamped action at a frequency in the sonic range. An alternative mechanical system is described that is vibratory at infrasonic frequency, with minimal damping and high amplitude. By a suitable choice of component values a resonant simple harmonic motion causes a tossing action at a frequency of 6 to 8 Hz. This action produces results not less consistent than those obtained with hand sieving.
A number of benefits accrue from the system described herein.