Protective coating for aluminium riveting tool/carbon fibre component

[mea02as]

Hello, we are currently working on a work placement designing a tool to be used to solve a problem with regard to riveting an aircraft part, what would be the most viable option for a protective coating. The tool is made from aluminium and the purpose of the coating is to protect the carbon fibre that the tool will come into contact with. We believe this coating will have to be some form of composite material, perhaps kevlar, as it must have a high impact resistance, toughness and fatigue resistance. If anyone has any input that they would care to share this would be valuable research material and much appreciated. cheers

 

[Sparweb]

MS20470 Rivets can be installed in composite structures, and they have protective coatings. I looked up the MS spec and it gives several processes:
"Anodize per MIL-A-8625, Type II, Class 1, Dichromate seal or,
Chemical surface treatment per MIL-C-5541, Class 1A, Clear or Gold/Yellow."
One or both of these are appropriate for Al 1100, 2024, 2017, and 7050 (there's a bit of latitude built into the MS spec).


Steven Fahey, CET

 

[mea02as]

Sorry, i didn't make it clear enough... The tool itself is made of aluminium and the part we are riveting is carbon fibre, the coating or protective cover is to be placed on the tool surface to stop it coming into contact with the component as there is quite a large contact area.

Cheers

 

[RPstress]

So you're just looking for something which will avoid accidental scuffing of the carbon?? If so, how thick can it be? A layer of PTFE would do that, if the mechnical loads on the layer are low. Nylon (6 or 6-6 maybe) would be cheaper and easier to stick on, but might be less forgiving to the carbon. If the forces on the layer are high, or if it's is in any danger of wear itself, then maybe try Torlon (a PAI) or similar. Obviously, you want to be avoiding any sharp or shock loads applied to the carbon. I take it these are blind rivets or solids being squeezed up?

 

[WKTaylor]

mea02as

Check with Kamatics Corp... they have several excellent composite wear/abrasion-material "types". The material forms I am working with are:

KARON [Grades A-to-V for sliding wear] and the Type P54 [sharp-edged cutting wear].

These materials are flat-sheet forms of their proprietary bearing liner materials that come in strip or sheet form and are bondable on one-side [fabric reinforced]. The thicknesses I specify range in size from 0.016-to-+0.125-inches [0.4-to-+3.2-mm].

Appear to work very well between disimilar materials and against rubber or rubber-fabric bulb-seals. I suspect your application would be no big deal for these materials.

NOTE: I am sure other companies have similar products... like PTFE-impregnated fabric sheets... but am unaware of them.

Regards, Wil Taylor

 

[wongweiyew]

mea02as

From my experience, we should not be riveting a composite laminate as this will cause delamination in the composite structure. Even with the use of cherry fasteners will cause delamination due to the impact while forming the rivet heads. There are specially designed fasteners used for fastening composite structures. These are jo-bolts and compsi-loks. The vendors are from united fasteners and monogram aerospace respectively.