Extrusion Screws and Barrels
for single screw and twin screw extruders
Extrusion
Extrusion Screws
We show our customers how to optimize processes, avoid
costly repairs and extend the life of screws, barrels and other melt
stream components. We know general purpose screws rarely meet the demands
of ever changing material and technology. Our decades of experience
with extrusion screw design allows us to work with every aspect of
plastics. Yashi
Screw has the capabilities to design, manufacture or rebuild screws for
a wide range of applications, including single-flighted,
multi-flighted, variable lead, two-stage and barrier. We have a wide variety of base materials, hard sufacings, platings, coatings, and heat treatments to choose from for your new extrusion screw. Yashi Screw’s standard base material for screws is AISI 4140 heat treated and stress relieved to standard (28-32 RC). OD surface of flights are either flame or hardened or hard faced with: Stellite #6, Stellite #12, Tungsten Carbide, Colmonoy #56, Colmonoy #83, Colmonoy #88, etc.
Single Screw Extrusion System:
We offer a variety of extrusion screw solutions including:
Carefully engineered screw profile or geometry to match the exact needs of your process;
High throughput, optimum mixing and melt quality;
Quality inspections with every step of the process in extrusion screws making;
On-site consulting and field services.
The extrusion screws we offer enable you to maximize extrusion throughput, product quality and component service life. All kinds of screws for extrusion are available: 3-zone standard screws, multiple thread screws, barrier screws, vented screws and twin screws.
Base Materials:
Alloy Steel: 4140 steel(AISI 4140), Nitralloy 135M, GB 38CrMoAlA, JIS SACM645, BS EN41B, 34CrAlNi7, DIN 1.8509, DIN 1.8550, 41CrAlMo7, or equivalents.
Stainless Steel: 304, 316, 416, 17-4PH
Tool Steel: D-2, H-13, DC53, CPM 9V, CPM 10V
High Nickel Alloys: Hastelloy C-276, Inconel 625, Inconel 718
Flight Hardfacing Materials:
Nickel base: Colmonoy #56, Colmonoy #57, Colmonoy #83, Colmonoy #88
Cobalt base: Stellite #6, Stellite #12
Surface Hardenings:
Gas nitriding and Ion nitriding, Chrome plating, Carbide encapsulating, PVD coating, etc.
The geometry of screws can be varied. Widely used for extrusion applications are 3-zone screws and barrier screws.
3-zone screws consist of 3 zones: feed zone, compression zone, metering zone
The feed section is the part of the screw where the unmolten polymer enters into the barrel. The rotating screw moves the material along the heated barrel where it starts to melt.
In the compression zone, gases like air and volatiles like moisture, are being removed. In the compression zone, the flight depth decreases and gases are pushed back into the direction of the hopper.
Finally, the material enters the metering section. In this section, pressure is generated which enables the material to be conveyed into the shaping area, like feed block or film die.
The compression ratio of the screw is the ratio between the flight depth of the feed section and the ratio of themetering section.
Most screws have a flight helix that is equal to the diameter of the screw.
Applications:
1. flexible packaging: film extrusion and co-extrusion (blown film and cast film)
2. rigid packaging: extrusion blow molding, rigid film and sheets extrusion
3. plastics recycling: film recycling and regranulating(HDPE/LDPE/LLDPE/PP),
non-woven spun-bond PP/PP woven bags recycling and pelletizing;
nylon/PA filament, net and mesh recycling and repelletizing
4. PET monofilament/strap extrusion
5. extrusion coating and lamination
6. cable and wire: PVC/XLPE cable jacketing and sheathing
7. plastic conduits, ducts, pipes, tubes and hoses
8. plastic profiles, sheets, boards and panels
