For giggles... in addition to Berkshire's post...
The following documents discuss this issue to greater/lesser extents...
SAE AIR5367 Machining of Composite Materials, Components and Structures
MIL-HDBK-337 Adhesive Bonded Aerospace Structure Repair
MIL-HDBK-349 Manufacture and Inspection of Adhesive Bonded, Aluminum Honeycomb Sandwich Assemblies for Aircraft
MIL-H-87990 [CX] Aluminum Honeycomb Sandwich Assemblies, Manufacture Of
The OBVIOUS KEY is to temporarily stabilize the core during cutting to attain clean deformation-free 'shaping'. This can be done in [2] ways...
Unexpanded core is easiest to machine for 'simple profiles'... since it can be machined on a compressed scale like a solid block of metal or plastic... then be carefully stretched/expanded to full size for installation.
Fully expanded core is flimsy and must be stabilized and cut with extremely sharp/thin/low-drag cutters/blades. Sacrificial face sheets and filler can be used, etc.
NOTES1.
a. Thick/stout core foil in a very small cell shape/size is the absolutely easiest to machine.
b. Thin core foil, in a large cell shape/size is the absolutely hardest to machine... along with honeycomb core that is designed to flex smoothly around curvatures [instead of going anticlastic spastic].
c. Cleaning the individual core-cells of cutting debris and adherent chips is a pain... must be flushed or gently blown-out... and adherent bits taken out with tweezers and Exacto blades.
Regards, Wil Taylor
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