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Davis-Standard,LLC

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Feedscrew Technology

Our ability to design and manufacture some of the industry’s top-performing feedscrews is one reason we have been an extrusion leader for nearly 60 years. With our R&D facilities and team of experienced polymer process engineers, we offer world-class screw designs and technical capabilities. Several types of barrier screw technologies are available based on the polymer(s) used and application. These include the DSB® I, DSB II, DSB III, DSB V, DSB VI, DSBM-T and Sterlex® designs.

 

Screws For Every Application

Screw sizes range from 3/4-inch (20mm) to 12-inches (305mm) for single screw, 40mm to 140mm for counter-rotating twin screw, and 32mm to 130mm for co-rotating fully intermeshing twin screw extruders. Screws, including smooth and groove feed designs, can be customized for specific applications.

 

Barrier Technology

The DSB® barrier screw typically consists of feed, barrier and metering sections with a dispersive or distributive mixer. This design introduces an additional flight over the transition section of the screw known as the barrier flight. This is advantageous because:

  • The barrier flight creates a physical barrier between the solid bed and the melt pool, so that the depth of each channel varies independently.
  • The barrier flight is undercut to allow molten material to pass from the solids channel (S/C) to the melt channel (M/C).
  • The melt channel becomes progressively wider and deeper along the barrier section to accommodate the accumulating molten material.
  • This geometry makes the melting process more efficient and improves stability.

 

Distributive And Dispersive Mixing

Our technology optimizes two types of mixing to achieve excellent melt quality – distributing mixing and dispersive mixing.

  • Distributive mixing occurs between compatible materials by the simple splitting and recombination of flow streams. The mixing mechanism is important to achieve uniform temperature distribution across the melt stream to uniformly incorporate minor phase components such as master-batches for color, UV stabilizers, and slip and anti-block. 
  • Dispersive or intensive mixing is energy intensive and uses shear stress as a driving force when processing blends of different components. This breaks down agglomerated components or incorporates a semi-compatible minor phase component into a major component.

 

Manufacturing Methods And Materials

Our screws are engineered in CAD format and transferred to manufacturing using a CAD/CAM system. They are then milled and ground on CNC machines to the highest industry standards. This CAD/CAM system ensures accuracy, repeatability, and efficiency. 

A wide range of raw materials and wear resistant technology is available for the full range of extrusion applications. Our engineers evaluate your application and recommend the best metallurgy for barrel, screw and flight surfaces.