“A.F.”UNDERHOPPER FORCED FEEDERS
For the return feed and mixing of chips produced from the EXACT Granulators back into the extrusion process, we suggest the use of one of our A.F. Underhopper Forced Feeders. The Exact A.F. Underhopper Forced Feeders mix the Exact chip with your virgin material and can also be used as a batch feeder.
The A.F. Underhopper Forced Feeder is available in two versions:
The Constant Speed A.F. are suitable to mix the EXACT pellet and forcibly feed it into a closed system, ideally positioned between the virgin pellet feed hopper and the extruder screw throat. The virgin pellet assists in moving the EXACT chips well into the extruder feed section.
It must always be used at a constant feed speed, and never as a batch feeder.
The Variable Speed A.F. is controlled by an Inverter. In addition to the forced mixing and feeding of the EXACT chip, when placed directly above the extruder screw and under the weight of the virgin granules, it is also used as a volumetric metering device. The digital screw speed display screen enables speed set point control required for dosing the feeding of EXACT chips in varying percentages.
By means of an analog signal, it is possible to synchronize the forced feeder screw speed with that of the Extruder, in order to maintain a constant percentage of fed material.
Screw diameters can be constructed in 60, 80 o 100
The EXACT chip is mixed with virgin pellets utilizing an elongated screw which extends into the extruder connector piece.
The CONNECTOR piece is always supplied with the A.F. which connects the Forced Feeder to the production cycle. These feeders are best positioned between the virgin chip feed hopper and the mouth of the extruder screw. The raw material pellet assists in moving the EXACT chips well into the extruder feed section while providing excellent mixing with the EXACT chip.This connector piece comes suitably sized to the screw diameter and feed rate.
To construct the connector piece, we require the bottom hopper dimensions, the extruder throat dimensions and the extruder screw direction.
(Size to be included in the sketch below).
or 100 mm and with 0.75 or 1.5 kW motors as required.
Theoretical feed rates vary from 10 to 500 Kg/h for the EXACT chip. Rates are dependent on bulk densities.
An angled and perforated stainless steel grid which sits inside the AF feeder hopper, acts as a sieve and can be easily viewed through an inspection window.
The large A.F. feed mouth dimensions avoids bridging problems even with light or bulk density chips.
CRUCIAL SELECTION PARAMETERS IN A.F. SIZING ARE AS FOLLOWS:
Extruder screw diameter.
Maximum extruder production rate, Kg/h.
Maximum quantity of EXACT chip to be fed, Kg/h.
All these data are essential, for :
A – Choice of diameter, to be suitable for the extruder.
B – Choice of gearbox ratio (for the capacity).
C – Choice of motor power range.
To feed material with high electrostatic charge or in instances of space shortage, a LOWER HOPPER FORCED FEEDER is also available.