With standard double row (4 teeth) indenter crimp tools (i.e., Daniels) on a
barrel pin/socket, the tool deforms the barrel into a shape like a square
except with indented arcs from each corner (hard to describe easy to
sketch). To have a capable joint, requires that the individual strands fill
the corners of this "square-like geometry." Tinning would probably hinder
this deformation. Dependent upon the lug and crimp tool, you may not
achieve this same geometry but the principle is the same. Cross-sectioning
can confirm whether a joint made outside the lug mfg recommendations is good
or not. Refer to European Cooperation for Space Standardization literature
on this subject for more information. You should be able to access it at:
http://www.ecss.nl/
-----Original Message-----
From: Kasprzak, Bill (sys) USX [mailto:[log in to unmask]]
Sent: Friday, May 17, 2002 6:32 AM
To: [log in to unmask]
Subject: Re: [TN] Crimped connections
Stu,
I've read all of the responses so far but think they all miss the mark. A
crimped connection is designed to "rearrange", for lack of a better word,
the strands of wire within a conductor. This "rearrangement" is created when
a crimp tool compresses the barrel of the lug so that the internal strands
can conform to this compression without breaking the strands. That's why
some crimp tools have different settings for different gauge wire. I've seen
video of crimped connections where this attachment methodology is actually
stronger than soldering the wire to the same lug. Therefore, tinning a wire
before crimping defeats the design of what crimping is supposed to do. We
crimp wires on a regular basis. We perform pull testing on crimped
connections and typically the wire breaks before the crimp pulls out of the
pin. Can't get any stronger than that! So, never tin a wire before crimping,
again never! However, would I rework the lugs that you have? Assuming
something less than class 3, probably not, but it would be the last time I'd
allow it
Bill Kasprzak
Moog Inc. Manufacturing Engineering, Electronics
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