Float Helicoil Options 3

[audacious2121]

Hello,
I am not sure if there is such thing, but we are facing issues aling parts at final assy, one part comes with helicoil preinstalled in them and other part with thru hole, alignining these is a nightmare. I was wondering if there is solution to have floated helicoil or nut inset? We can always try backdrilling, but that will be added operation at final assy level, which we are trying to avoid. Thanks

 

[3DDave]

As vague as your problem is I can say there are equally vague solutions. Helicoils cannot float, but there are floating fasteners.

 

[IRstuff]

OK, that's just silly approach; you need to figure out WHY things aren't lining up. Are the subassemblies' tolerances out of whack? Are they being drilled incorrectly? Any post-machining or "fixes" are just simple NOT part of a proper manufacturing process.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[SWComposites]

To add to IR, are you using drill templates, or CNC drilling, or hand drilling.
How much oversize are you drilling the mating part thru holes?
Are the hole position tolerances the same on both parts? Relative to the same datums?

 

[IrishMariner]

I would agree that this problem should not need a floating helicoil to fix.

Our normal practice (typically transmission & accessory cases) is to have the basic non-floating MS21209 helicoil take care of clamping (the mating part having a hole large enough to tolerate helicoil position tolerance) and a single dowel (NAS607) elsewhere on the flange to handle the shear loads. The tolerancing required to do this presents no issues for the contract machine shops whatsoever. The way it was explained to me is the helicoils are there for clamping/fluid sealing and the dowel for alignment and shear capability.

FYI - Howmet/Alcoa do offer a floating Helicoil as part of their 'Special Purpose' Keensert range.

 

[audacious2121]

Sorry for vaguness in my post. One part (cureved panle) has embedded metal in composite panel, for which we have helicoils. Mating part is also composit part with thru inserts in them. The hole alignments happens two flat sides of curved panel. I will take the recommendations and look thru how dimensioning is, relative to common datum. We are not using drill templates, will try to understand the helicoil instl better. @irishmariner really like this idea of creatign large enoug hole and have dowel take care of shear loads & also look in to Keenserts.

 

[rb1957]

"one part comes with helicoil preinstalled in them and other part with thru hole" there's your problem ! Sure you can work with common CAD models, or common tooling.

If this is for a large production run, then using matching tooling is the way to go.

If this is a small run, then installing the helicoils on final assembly would be better.

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[erik3000]

Maybe a barrel nut, instead of a helicoil. e.g. NAS577