Composites

Making a Mold

  • Ensure clean, smooth surface
  • 5 coats of mold release wax
  • 5 coats PVA
  • Tooling gelcoat 25-35mm
    • 5 coats with a brush
      • Must be tacky when subsequent layers applied
      • Short pot life, so ensure that multiple coats are pre measured
  • Slurry paste in grooves
  • Precut material; mold should be at least 5x thickness of part being made
  • Coat surface with tooling resin
  • Veil mat (prevents print through); thin with continuous fibers. this prevent the short fibers from poking through the gelcoat
    • Completely wet it out
  • Medium weight cut strand mat
    • Lay down
    • Wet out
    • Compact with rollers
  • Woven Cloth: adds bi-directional stability
    • Lay down
    • Wet out
    • Requires less resin that cut strand
  • Bulker Mat: non-woven, high-density
    • Lay down and wet out
  • Stiffeners
  • Medium weight cut strand mat
  • Woven cloth

G100 Gelcoat Gun

  • Good video overview here
  • He runs at 100psi

 

Notes

  • Pot life is calculated at ambient temperature of 70 degrees
  • Cure time is inversely related to temperature
  • Weaves
    • Plain
    • Twill; diagonal herring bone pattern (common for carbon finished carbon fiber parts)
      • 2x2 and 4x4 (looser) are common
  • Satin; very flexible, not as attractive
  • Toe size; number of strands x number of fibers per strand
  • Drapeability; weave + toe
  • Zilon; super strength, high temp
  • PVA
    • Spray: going to start with 30 psi
    • Spray for 1 second 12" from surface; spray fan should be 12" wide, uniform, wet with no drips or sagging
    • Spray at 1-2 feet per second perpendicular to the surface

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