Peel Ply Caution

[longez360]

Everytime I read of someone saving a few bucks by using substitute materials, I get on my high horse. Sorry gang, I gotta get this one off my chest.

 

Of late I have read of a number of people using all kinds of commerically available peel plys, that once removed, the resulting surface is considered structurally prepared surface for adhesive bonding. This is not necessarily the case, and structurally can be as bad is it gets.

 

Are you meeting your peel strength requierment? Are you leaving behind a clean, chemically active surface? What about contaminants?

 

The only effective method of surface preparation is surface abrasion.

 

Issues:

 

1. Peel ply Fabric density - warp/fill/filament size - effects bond due to varying resin impregation.

2. Contaminants and material transfer - some nylon peel plies contain silicon. Some leave the peel ply material on the surface. Like any materials used in our method of construction they MUST be clean and dry.

 

There are many industry reports on this subject available on the internet.

 

Surface abrasion has its pitfalls also.

 

Peel plies that leave a "beautiful surface" are dangerous. Use on primary structure is not 'at your own risk', it may also be at the risk of those you fly with or over. Beware.