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Developing Profile Extrusions Dies

Modified on Monday, 02 February 2015 01:20 PM by mpieler Categorized as Extrusion Hints
Developing Profile Extrusions Dies is misconstrued as a “Black-art” not the science that it is, only because many do not take a scientific, systemized approach on a consistent basis. Listed below are some guidelines that will help the Die Designer/Engineer to correctly approach the development phase of profile extrusions.

Balanced Wall Profiles:
Walls are designed with equal land length

  • RPVC Pellets 10:1
  • RPVC Powder15:1
  • High Output PVC Powder 25:1
  • LDPE: 15:1
  • ABS: 25:1
  • Development Technician runs overall profile width to specification
  • After measuration, if walls are thin, wire EDM respective wall 50% of final desired thickness. (Polish)
  • Appendages short, wire EDM for proper wall thickness first
  • If appendages are correct wall but short, wire EDM delta difference

    Unbalanced Wall Profiles:

    Walls/appendages are designed with an “Equal Land Length Ratio”
  • Development Tech runs overall profile width to specification
  • After measuration, if walls are thin, wire EDM respective walls 50% of final desired thickness (Polish)
  • If appendages are short (Flat back die) drop land length
  • If appendages are short (SL Die) wire EDM wall

  • All walls are polished and recast is removed
  • Flow diverters are used with diverter thickness added to wire burn
  • Profile does not exceed barrel gate adapter

    Cap-coat Balancing:
  • Runner is calculated to contain volume equal to, preferably greater than volume to cap-stock surface
  • Pre-land area follows the annulus runner. Preferred design should include a tapered descending pre-land.
  • Balancing should be done on pre-land by dropping the pre-land depth
  • Latest technology suggests secondary pre-land area and two annuli channels

  • All channels are symmetrical
  • End of annulus channel to be streamlined to prevent stagnation
  • Cap-stock thickness is designed into die lip plate over substrate layer
  • High viscosity degradable resins and thin cap-coats should utilize 45 degree approach (Male/female)

- Dan Cykana, Bemis

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