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        Home >>FAQ

        How to choose screw and barrel?

        1. Determine the diameter of screw,length of screw, outer diameter of barrel

        2. Checking plastic material and plastic type,new plastics or recycled material?

        3. Confirm the steel material grade, nitriding grade,bimetallic grade or Tungsten carbide grade, which is based on anti-wear ability and hardness.

        4. Making drawings of screw and barrel,or ask technician from factory about available drawing

        5.Choosing good factory to manufacture screw and barrel.

        Processing Problems Due to Improper Screw Design 

        The volume of the melt channel must be large enough to accommodate the polymer melt or a flow restriction will result because the melt will be compressed and forced to occupy the solids channel or leak backwards over the primary flight into a preceding section of the screw. The leaking of material over the main flight will increase the temperature of the exiting polymer. In both cases, this surplus molten material will interfere with the melting process reducing the output of the screw. Furthermore screws whose geometry does not match their melting behavior have higher pressures in their axial profiles. This is the main cause of premature screw wear since the high pressures will cause the flight of the screw to be pushed against the barrel wall. Once the melt and solids channels are sized to match the melting behavior of the polymer various process improvements can be realized. The main advantages include lower pressures along the screw, higher throughput rates due to lower melt temperatures, and lower pressure fluctuations causing stable extruder operation. 

        Whatever your application, we can work with you to solve your extrusion process problems or improve your current standards at a price you will agree is very competitive. Using our proven scientific approach to screw design we avoid the costly trial and error work that has historically plagued screw design. In a world where process optimization makes the difference in profitability, you need an extruder screw that is able to perform to today's ever increasing demands. We draw from our experience and knowledge base to provide you with an extruder feed screw and barrel to allow you to meet today's and tomorrow's demands.

        Standard Feed Screw Construction Features:

        • Chrome plating in root

        • Wear resistant full flight width Colmonoy 56, 83, X830, or UCAR

        • Spiral or straight Maddock mixing section for dispersive mixing

        • Pineapple, Saxton, or pin mixing section for distributive mixing

        • Highly polished streamlined surfaces

        • High quality materials and construction (manufactured from aircraft quality 4140, 4340, stainless steel or Duranickel)

        Standard Barrel Construction Features:

        • Bimetallic construction

        • Guaranteed straightness of 1 in 20,000

        • 58-64 Rockwell C

        • Finish to within 8-12 micro-inches

        • Enhanced abrasion and corrosion resistance

        Process ImprovementEffect
        Lower pressures along screw axisReduced screw wear maximized pressure
        stability and less power consumption
        Less compression of meltOptimized melt temperature and stability,
        maximized output and less polymer degradation
        Efficient meltingHigher melt quality (no gels), at higher outputs
        No flow restrictionHigher output and pressure stability
        Improved mixing / meltWider blending ranges, uniform melt properties
        and maximized process flexibility
        Streamlined designCleaner operation

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