Machining Un-Laminated Honeycomb

[Charles Davis]

Does anyone have experience machining nomex honeycomb, before it is laminated?

 

With a .25" flat cutter it tends to tear and fray -even at 18,000 RPM.

 

I was thinking of going with a high speed air driven spindle 50,000K+ and a smaller tool.

 

This is a "captive" shop and does not compete with anyone.

[crazy^millman]

It always wants to string even with the hihger rpms. I would say if it can get wet then water-jet it. I have tried to put heavy paper over this stuff spray with adhesive and have limted luck doing so. I have seen people take an make a template on the router then go to a band saw to cut shapes. A diamond tools will somtimes yeild results but need atelast 24,000 rpm to be effective IMHO.

 

HTH

[mcpgmr]

At Boeing helicoptors we had to machine aluminum honeycomb floor panels for the CH47. The honeycomb would come to us filled with a blue water soluable wax. After machining the wax was washed out. We didn't need high rpm spindles to cut this stuff just a sharp e.m. HTH !

[Chip-pan]

Waterjet, laser, or bandsaw. Its the only way that stuff cuts.

We tried high rpm. It still ripped the material apart.

 

Chip Pan

[billystein]

We have used wax to fill in the honeycomb. then we used flat bottom end mills to cut the part. tooling was pretty regular.with dowels and clamps. to melt the wax out we made a big wooden box with a hole in one end for a heat gun. it isn't very fast but it will melt the wax out just fine.

 

billy

[Craig Madsen from CM3D]

A couple of customers use ECG (Electro-Chemical-Grinders) to cut extremely thin / Delicate materials.

 

However, The machinable wax sounds workable - depending on the thickness of the base material.

[mcpgmr]

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However, The machinable wax sounds workable - depending on the thickness of the base material.

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I don't know what the wax was called but it looked and felt like hard soap. Once you applied water to it the wax would just wash away. The wall thickness of the honeycomb material was only like .006 and the wax was more than enough to keep it stiff for machining.

[DTHOMSON]

How about freezing it in a cavity filled with water...like an ice cube?

[Craig Madsen from CM3D]

Water expands when becoming ice. That would probably tear the honeycomb apart. (I know it will explode a bottle of beer left in the freezer too long)

[Charles Davis]

It cuts great with a "valve stem" cutter, but you can only tilt the head so far before the 5-axis head hits the table.

 

Also, you can't put in tight radii.

 

I thought of the template idea. At this point, the customer seems against it, but I think this might be the only solution that can yield good results.

 

You guys are great. Thanks for taking the time to respond!

[mkd]

I’m cutting phenolic coated paper honeycomb on a 5 axis router. We use curve 5axis paths for facing. Both rough and finish passes we use .25° lead angle to keep the back of the cutter from dragging. With a 3 in dia cutter, is this angle too much, not enough or just right??

Thanks

[Colin Gilchrist]

Hi Charles,

 

We've been testing some really nice core shaping cutters. The valve stem type comes in larger sizes, but we've had great luck with some smaller cutters, I think they are made by Onsrud. The ones we are using are .375 Dia, and they work just like regular endmill in normal material. There is no need to cut only with the edge of the cutter like the valve stem style.

 

Rick Henrickson has been doing the test cuts, I'll ask him tomorrow.