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STEER has also introduced elements with enhanced conveying
efficiencies for use in the intake zones of the extruder. The elements
are characterized by the number of flights and share the negative
angle undercutting of the pushing flight.
SFV elements are based on a uni-lobe profile with a pushing flight
machined at a negative angle producing a concave form. The
element profile has shown a significant increase (in some cases
greater than 200% improvement) in conveying efficiency for low bulk
density and powder feedstock when used in the feed zone.
Screw element types can be separated into three categories:
1. Intake; 2. Melting; 3. Mixing. Some elements are multi-
functional in design and can share more than one category.
7. SIDE FEEDER AND VACUUM SIDE STUFFER
a. Side Feeder
Side feeders are often employed on twin-screw extruders to laterally
feed dry materials into the extruder’s process section. Side feeders
typically have two self-wiping, closely intermeshing screws providing
positive conveying of materials. There are multiple advantages
associated with the use of side feeders.
i. Improved feeding of difficult powders and fibers
ii. Reduced screw and barrel wear
iii. Higher quality and/or production rate
b. Vacuum Vent Stuffer
Vacuum vent stuffers are used to apply vacuum to the process section
to remove gas entrainment in the melt while simultaneously
preventing the melt from blocking the vent opening. Advantages
associated with the use of vent stuffers are:
i. Improved volatile removal
ii. Decreased downtime due to vent blockage
iii. Higher quality and / or production rate
STEER side feeders and vacuum vent stuffers are both designed for
RFV elements are based on a bi-lobe profile with a negative angle
mounting laterally to the extruder barrels. Side feeders and vent
undercut pushing flight. The element offers enhanced intake and
stuffers are usually mounted on the downturn side of the extruder
conveying efficiency in side feed zones.
screws for optimum performance, however it is possible to locate the
equipment on the opposite side if required. The STEER side feeder is
available with optional quick disconnect Jiffy Clamps to facilitate
cleaning and maintenance. STEER side feeders and side vacuum
vent stuffers share a common design for gearbox and screws. The
gearboxes are designed for extreme service and have special features
allowing a high degree of flexibility.
The screws of the STEER side feeder and vacuum vent side stuffer
borrow from the extruder’s segmented element and shaft design.
TFV elements are based on a tri-lobe profile using fractional lobe
The screws are decoupled from the gearbox output shafts via a
technology. The pushing flight also features a negative angle
connecting zone in the same manner as the extruder. This approach
undercut. The TFV element can be effectively utilized for force fed
provides the ultimate degree of process flexibility, allowing for
zones such as vertical densifier feeders and side feeders.
specialized configuration of the screw elements. The STEER side
feeder and side vacuum vent stuffer are fitted with high performance
gearboxes with thrust bearing assemblies which provides the highest
level of reliability and service life expectancy. The devices are
available in two mounting configurations: extruder frame mounted
support or a separate mobile support stand.
[ Refer the table in Page No. 12 &13. ]
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S C R E W S P E E D ( r p m )