Quarter turn/Quick Disconnect Fasteners
Quarter turn/Quick Disconnect Fasteners
(OP)
Does anyone know where I can find some high-strength quick disconnect/quarter turn captive fasteners? I've looked into CAMLOC/RAM fasteners and have not found anything that will work. The standard Camloc series are not strong enough (looking for something with allowables similar to an NAS1993 or other 10/32 screw) for the application, and the heavy duty series tend to be too large of a diameter to function in this application (must be .250 dia or less). The fasteners must be approved for aerospace applications, and something maintenance friendly and easy to find (for replacement parts) is preffered. I've nearly exhausted all of my resources so any information/help is appreciated.





RE: Quarter turn/Quick Disconnect Fasteners
RE: Quarter turn/Quick Disconnect Fasteners
Dzus
RE: Quarter turn/Quick Disconnect Fasteners
RE: Quarter turn/Quick Disconnect Fasteners
RE: Quarter turn/Quick Disconnect Fasteners
RE: Quarter turn/Quick Disconnect Fasteners
The shank dia can be no more than .250, though .190 is definitely preferable. We've speced out a captive screw which does the job, but is not very maintenance friendly. That's why I need a 1/4 turn instead, as this is the main avionics bay door, so it's open basically any time the plane is on the ground for one thing or another.
RE: Quarter turn/Quick Disconnect Fasteners
RE: Quarter turn/Quick Disconnect Fasteners
As far as I know, all quarter turn fasteners work the same way. You turn the fastener, and it engages and compresses a spring. The clamping forces are inherently low. The engineering of tiny, high force springs is difficult, especially if the assembly must survive repeated engagements. The stud is engaged by a receptacle, which is usually a subassembly of some sort, that allows a lot of room for the stud to move around.
None of this says "high clamping force" to me. If the stud is will constrained, you may get a high shear force out of it.
Low clamping force is an inherent disadvange of quarter turn fasteners. Would a lot of quarter turn fasteners be less inconvenient than a few captive screws?
JHG
RE: Quarter turn/Quick Disconnect Fasteners
Well, drawoh pretty much tells it like it is. At .250 diameter, you might be able to "custom make" a fastener in a high-tensile or hardenable steel; 2.5 kips in a .194 fastener is starting to push the limits of the ordinary steels in even a captive configuration, much less the details required for 1/4 turn.
RE: Quarter turn/Quick Disconnect Fasteners
RE: Quarter turn/Quick Disconnect Fasteners
h
RE: Quarter turn/Quick Disconnect Fasteners
RE: Quarter turn/Quick Disconnect Fasteners
Just curious, but any idea why the design went away from snap latches to captive fasteners? Latches do seem more maintenance-friendly, but maybe they were an aero drag penalty?
RE: Quarter turn/Quick Disconnect Fasteners
RE: Quarter turn/Quick Disconnect Fasteners
RE: Quarter turn/Quick Disconnect Fasteners
http://www.ftc-usa.com/captivefasteners.html
RE: Quarter turn/Quick Disconnect Fasteners
Something just occurred to me.
If your boss is absolutely determied to have a quarter turn fastener, you can design a high-strength one.
1. Your stud slides into a long, accurate hole in your recptacle, such that it has high strength in shear.
2. For each position to be secured, use two fasteners, rotated ninety degrees apart. Perhaps you can design the receptacle with both positions.
For this arrangement to fail, at least one of the fasteners must shear. Use high strength materials. Get an aerospace PEng to sign off on the design.
Nothing is impossible if you are willing to pay for it!
JHG
RE: Quarter turn/Quick Disconnect Fasteners
James Bennetts
Aerospace Engineer
RE: Quarter turn/Quick Disconnect Fasteners
RE: Quarter turn/Quick Disconnect Fasteners
James Bennetts
Aerospace Engineer