How to bond aluminium honeycomb

[ctcomposites]

I have a job coming up that requires bonding flat fiberglass sheets to Al. honeycomb. I was curious if there were any special preparations I should take with the Al. to insure a strong bond.

Thanks.

 

[CoryPad]

Yes, you need to clean and activate the surface. Check with companies that specialize in metal pretreatment and adhesives (like Henkel, 3M, etc.).

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[wes616]

See Mil-Hdbk-23 chapter 14.

Recommend Vapor Degrease.

Wes C.
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[spudpeeler]

I agree with wes616 that vapor degreasing is the best way to clean dirty core but if the core is kept clean it is ready to bond to straight from the vendor. It is extremely rare for a sandwich structure bond to fail as a result of the core pullng out of the adhesive.

What is most important to good bonding is to make sure that the adhesive forms good fillets against the core walls and does not run down the cell walls or fail to flow enough to form the filets.

Serious contamination can affect fillet formation but clean core does not require degreasing, or any type of surface prep like PAA or FPL, to bond well.

 

[Compositepro]

I am not an expert on core, but I believe that spudpeeler is correct. Most core is pretreated by the manufacturer for bonding as bonding is done to make the core itself. To get good reliable adhesive bonds to aluminum it does need proper surface prep.

 

[Hansmeister]

What is not clear in the original posting are:

1. Fiberglass facesheets - Wet Layup, prepreg or purchased?
2. Core - Aluminum: What thickness, cell size, and foil size?
3. Bonding - Film adhesive or thickened epoxy?
4. Shape - Flat panel or curved within a tool?
5. Pressure - Vacuum bag or weights?

Without the clarity of the part and the untented process, little help can be offered.

 

[mighoser]

I've used FM300 on carbonfiber/epoxy facesheets to hexcel aluminum honeycomb.