Centrifugal Sifters Are More Efficient, Save Space, Provide Cleaner OperationReprinted from FOOD PROCESSING
NORMAN SCHMITT, Plant Manager
ROBERT KLEIN, Plant Engineer General Mills, Inc., Toledo, Ohio
WM. S. STINSON, Associate Editor
At the General Mills, Inc. plant in Toledo, Ohio, the 60"-diameter vibratory sifter being used was not doing a satisfactory job on oat and corn based cereal products. Too much product was being carried over into tailings. The sifter created a dust problem, and occupied precious space.
Rearrangement of regrinding equipment for processing cereals, in 1972, provided an opportunity to replace the vibratory sifter with two floor-mounted 60 to 80 Ibs/min centrifugal sifters, located side-by-side. This arrangement permits handling one or two products at a time and direct delivery of siftings to storage facilities on the floor below.
The sifters feature dust-free, sanitary operation; quiet, vibration-free action; quick sieve change, when necessary, through a large inspection and clean-out door with transparent window; double seal outboard bearings; gentle sieving action; compact design; and low power requirements.
Material is uniformly fed into the cylindrical sifting chamber by a feed screw which discharges into a rotating helical paddle. Centrifugal force accelerates movement of particles against the sieve. Since" there is no contact between the rotating paddle and the sieve, sifting action is gentle enough for the safe handling of fragile materials. The sieve is attached to the supporting basket so that vibration is induced by the rotating paddle assembly and the solids being processed. This method of suspension also provides the resilience, which enables the sieve to absorb considerable impact from tramp material.
All parts of the centrifugal sifters, including the 12-mesh screen, are made of Type 316 stainless steel. The unit is vented to handle blow-back from a rotary valve which feeds screened flour into the pneumatic conveying system.
These sifters are applicable for handling a wide variety of dry or moist powders and granular materials, including milk and baking powders, casein, animal feeds, dry blood, brewer's grains, cocoa, starches, dextrin, soy, potato and fish flour, spices, whey, etc.
The smaller, more compact sifters do a better job with minimal carryover into tailings. Operation is practically dust free. The sifters are vibration-free and easier to maintain.