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prevent long fiber pieces from balling up at the exit of the inlet hopper. See the section
ahead on Cord Cutters.
The final plate, the C Plate, supports the discharge end of the screen. The cake
discharge spout is bolted to the C Plate. The discharge cone touches the spout
when the cone is in the closed position.
KP-24 and KP-30 presses have a fifth plate, called the D Plate, on which air
cylinders are mounted.
SCREW LIFE
If a press loses its previous throughput capacity, or if cake moisture content
increases, it is can be sign of a worn screw.
A screw can last anywhere from six months to twenty years. It depends on the
material being pressed and how hard it is being pressed.
Premature screw failure can arise from several causes. The two main ones are:
(a) If a press is allowed to run continuously even when no material is being fed into
it, the screw can wear out in one or two months. The same can happen if a very low
flow is consistently fed into the press.
(b) If abrasive material is dewatered with high cone air pressure, rapid wear will
occur. This condition is avoided if a few drops of water can always be squeezed
from a fistful of press cake.
Two effective ways to extend screw life are:
(a) Various grades of hardsurfacing rod can be used to protect the flights of a
screw. The best hardsurfacing will have Tungsten Carbide impregnated in it.
(b) Using a VFD or lower speed motor to reduce the screw rpm will extend screw
life
If a worn screw is suspected, the thing to do is to shut down the press, open the
cone, and dig out the cake until the tips of the last two flights can be seen or felt.
Check how badly the tips are worn. If the there is 3/8” between the tips and the
screen, wear is evident. It is also an indication that the sharp edges of the flights
throughout the press may have worn, becoming rounded. This can cause the
flights to act like a putty knife, plastering solids against the screen, preventing
water from coming through.
Worn screws are either restored locally or returned to Vincent for rebuilding. The
maximum cost of a screw rebuild is around one third the cost of a new screw.
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