Honeycomb core machining 1

[Jim85]

Hi,

I've recently started machining honeycomb core (nomex) on a cnc milling machine. I'm having some difficulty with this. I have heard from some guys that I used to work with that they have seen a substance that gets applied to the core which takes up the cells before machining. The core is then dipping in a dip bath after machining which breaks down this substance and you are left with the machined core in tacked.

Does any one know of a process like this? If so what are the names of the materials used?

Grateful for any help.

Jim

 

[Jim85]

I have recently found a product called aquapour. Do any of you know of this product? I have also heard of a wax solution that can stabilise honeycomb core but I do not know the name. If any one could point me in the right direction that would be great.

 

[berkshire]

one wax solution that used to be used was cetyl alcohol.
I do not know if it is still available.
B.E.

The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor

 

[materialsliz]

We use a material called Corefix to stabilize honeycomb prior to machining. We bond it to one side of the core and machine the unbonded side. After machining we use a heat gun to gently heat the Corefix and it peels right off. Have had great success with it. I've heard of Aquapour but our customers don't allow us to use it.

 

[allcomposites]

Acuapour is a great solution to this machining problem. Wax is also solution if you can properly decontaminate the nomex. Another solution is to make your own paste with resin mixed with hollow glass micro-spheres. In this case the edges of the nomex will be stiffer but heavier.

For a more technological solution, you have the Flexible Tooling (kind of bed of nails) that holds the honeycomb cells that are not machined. This is more frequent in serial production.

 

[Jim85]

Do any of you know the name of the wax solution that can be used?

 

[AlgoFlash]

I tried wax on my own but was not able to remove it completeley so sorry but I have no solution.

However, I have used the resin filled with micro-spheres with great success but would consider the flexible tooling rather than wax if I can't add anything in the honeycomb. I think you can create something with nails if your honeycomb is small enough.

I always wondered if it would be possible to heat the honeycomb in order to form it. Like using an iron to shape it...

 

[SWComposites]

Is this honeycomb being used in aerospace parts? If so, does the applicable process spec allow for the use of any core stabilizers? If not, then you should not be using them. Material left on the core after machining can lead to poor bonds between the core and facesheet.

 

[allcomposites]

Yes you can thermo-form the nomex. You heat it up to 400 F (my memory may not be good here) and then press it to the desired form. This is common practice for many aeronautical pieces like radomes.