Comparing Twin Screw Extruders and Single Screw
Extruders
Twin screw extruders
Twin screw extruders are the classic machines used in compound
production. That is when two or more ingredients are mixed and extruded
in order to produce a pellet.
Twin screw extruders are particularly useful in the production of rigid
PVC and wood fiber blends.
Twin screw extruders with co-rotating, intermeshing, segmented screws can
be considered as ideal machines for the preparation of polymer compounds
with high percentages of fillers, reinforcing fibers or with particularly
heat-sensitive (frame retardants) or shear-sensitive (glass fibers,
microspheres) additives.
A machine which is equipped with a vacuum pump for degassing, with
cylinder cooling and screw cooling will be preferred for composite
compounding. A volumetric dispenser to supply the material is required,
as well as a stainless steel hopper.
Single screw extruders
Single screw extruders are useful machines to be used in production when
a pure polymer is used such as HDPE.
A single screw machine will produce plastic wood or other profiles from
regrinding chips with out the need for pre pelletizing.
Single screw extruders can be supplied with all kinds accessories:
automatic gravimetric feeders, vent vacuum units, heat and pressure
controllers, heat exchangers, melt pumps, static and dynamic mixers,
microprocessor control systems, as well as with a wide range of screw
geometries for different materials and products.
A machine are equipped with an air cooled barrel will be
preferred for producing HDPE products.
