DIY Network

The Curing Process The Curing Process From "Trade School" episode DTRS-108

In this segment, Sean cures the plane's composite panel with vacuum pressure and heat ....

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Materials:
Fiberglass cloth
Kevlar fabric
Peel-ply
Cotton bleeder cloth
Honeycomb core
Epoxy resin and sow hardener

Basic Tools:
Wood tongue depressor
Paintbrush
Vacuum press
Scissors
Razor blade
Band saw

• To prepare for the next phase of the project, Sean places base of cotton bleeder between two sheets of peel-ply on a plastic board within a square gasket (figure A). The peel-ply keeps the work from sticking to the board, and the bleeder helps to absorb any excess resin. Then he places the first half of the panel upon the peel-ply, honeycomb side up. He places his other panel half on top of the honeycomb Kevlar side down. He tops this with another sheet of peel-ply, a bleeder and a final sheet of peel-ply (figure B). Then he trims any loose strands with scissors.

  Figure A

  Figure B

  
  

• To cure the panel, Sean utilizes a vacuum press with a heat blanket attachment (figure C). After laying the heat blanket over the panel, he places a thermal coupler over the heat blanket (figure D). The thermal coupler monitors the temperature of the heat blanket.

  Figure C

  Figure D

  
  

• With everything in place, Sean begins securing vacuum bagging film over the panel and presses around the gasket to achieve a firm seal around the panel (figure E).

• Next, to insert the vacuum valve, he lifts up a corner of the bagging film and cuts an X-shaped slit into the film using a razor blade (figure F). He places a piece of cotton bleeder under the valve to allow for the passage of air from inside the bag. He reseals the film over the square gasket and closes the valve (figure G).

  Figure E

  Figure F

  Figure G

  
  

• Sean uses the vacuum to remove the air inside the plastic casing. This forces the resin to bleed through all the layers of the panel. Sean maintains 18 inches of vacuum pressure for three minutes (figure H).

• Next, Sean heats the panel to set the resin. The thermal couple gives an initial reading of 73 degrees Fahrenheit. He turns on the heat blanket, and raises the temperature in increments of ten degrees every ten minutes until reaching 140 degrees. Then he maintains the vacuum pressure and the temperature for 2.5 hours. The heat and the vacuum cause the resin to distribute throughout and harden.

• After 2.5 hours, he removes the peel-ply layers and trims the panel with scissors (figure I). Then he cuts the panel to size using a band saw (figure J).

  Figure H

  Figure I

  Figure J

  
  

• In the next segment, we follow Sean as he inspects and rebuilds a radial airplane engine.