Slight Moisture Ingress into Sandwich Panel
Slight Moisture Ingress into Sandwich Panel
(OP)
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Slight Moisture Ingress into Sandwich Panel
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Slight Moisture Ingress into Sandwich PanelSlight Moisture Ingress into Sandwich Panel(OP)
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RE: Slight Moisture Ingress into Sandwich Panel
I've understood that it could be used to cut sandwich panels; I just haven't seen a video before.
Are you concerned about some part of the process?
Mike Halloran
Pembroke Pines, FL, USA
RE: Slight Moisture Ingress into Sandwich Panel
Water jet limits you to through cuts only, no pre-drilled holes for potted inserts etc.
RE: Slight Moisture Ingress into Sandwich Panel
RE: Slight Moisture Ingress into Sandwich Panel
I said I was familiar with the process, not that I would recommend it for an application so far unrevealed.
I think I read somewhere that the waterjet doesn't seriously affect even paper-based core, because the flow is actually pretty low, but I would worry about abrasive contamination for aerospace panels.
Most people today don't bother to prepend 'abrasive assisted' to 'waterjet cutting'. I think the high pressure water alone will cut most materials, but feeding some grit into the stream makes it cut _much_ faster, certainly enough to change the economics of the business.
Then, someone has to remove the stray grit from the workpiece. The local waterjet cutter associated with my former employer doesn't do it, probably because their entire facility is awash in abrasive dust.
Mike Halloran
Pembroke Pines, FL, USA
RE: Slight Moisture Ingress into Sandwich Panel
STF
RE: Slight Moisture Ingress into Sandwich Panel
RE: Slight Moisture Ingress into Sandwich Panel
Thank you for mentioning the abrasive - informative.
While flow may be low, the pressure is of course very high. Wouldn't you be concerned about moisture penetrating into the honeycomb?
For an application, how about a galley structure of a pre-existing design with adhesive bonded structural joints previously validated by test. If the tested part was done by pin router could you cut the parts by water jet without need for additional structural tests? Presumably, disbond & other NDE checks make water jet more expensive than pin routing - so can we rule them out?
RE: Slight Moisture Ingress into Sandwich Panel
Routers, on the other hand, tend to throw chips radially, i.e., into the cavities within the core, so cleanup may be more difficult than for a waterjet. OTOH, they do allow making blind cuts and even undercut pockets for embedded attachment points.
I think galleys and beverage carts are already made from sandwich panels, and have been for a long time. Maybe a little social engineering could net you a tour.
Mike Halloran
Pembroke Pines, FL, USA
RE: Slight Moisture Ingress into Sandwich Panel
We manufacture honeycomb floor panels this way. The floor panels consist of aluminum skins [pre-PAA/primed], aluminum honeycomb core [PAA], film adhesive and edge potting compound.
Here's how we make them...
Per each panel drawing there is a common 'raw stock size' for both the (2) skins and the honeycomb core. In most cases there are skin thickness differences [upper VS lower] and obvious differences due to LH-RH mirror-image construction. It used-to drive the shop nuts making LH and RH panels from finish-trimmed materials.
Duhhh... then we had an idea...
We tried bonding the raw-stock skins to the raw-stock core, then routing these raw HC raw-panels to either a LH or RH configuration. Almost instantly, the idea of cutting these raw HC panels to final LH or RH trim using NC water-jet cutting [W/WO abrasives] was proposed and tested successfully. The 'GREAT CAUTION NOTE' here is that the upper-surface has to be identified so that the panels aren't inadvertently trimmed backwards [IE: MUST maintain thick-skin side UP]. Various sandwich construction test methods proved that this method worked without any deleterious effects to the panel structure [shear, t-peel, crush, etc]. Many man-hours and much 'frustration' have been saved with this method.
After water jet-cutting, the next step is to under-cut [recess-cut-out] the exposed edge HC-core by hand; and then potting the recessed HC edges with low-density potting compound [filled-epoxy] for moisture sealing and edge-crushing strength. The finished panel is then coated with epoxy primer, all-over. NOTE. The time between water-jet cutting and under-cutting the exposed HC edges, and then potting the edges, is sufficient to allow the trimmed area to be thoroughly dry long-before the potting step.
NOTE. This 'process' also works well for constant thickness crushed-core HC panels; and sandwich panels with non-metallic HC core.
Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion"]
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RE: Slight Moisture Ingress into Sandwich Panel
RE: Slight Moisture Ingress into Sandwich Panel
Any minor disbonding between skins and core that might occur along the water-jet cut edges is pretty-much eliminated by the HC-core under-cutting/potting procedure.
Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion"]
o Learn the rules like a pro, so you can b
RE: Slight Moisture Ingress into Sandwich Panel
Even a small amount of humidity or trapped moisture in the cell spaces of a honeycomb material can cause delamination problems if the panel is processed in an autoclave or oven at elevated temps. Also, recall how moisture trapped in the spaces of the aluminum honeycomb used for the X-33 composite cryo fuel tank structure caused delamination failure during testing.