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
> -----Original Message-----
> From: [log in to unmask] [SMTP:[log in to unmask]]
> Sent: Thursday, May 16, 2002 7:46 AM
> To: [log in to unmask]
> Subject: [TN] Crimped connections
>
> All-knowing TechNet,
>
> Yesterday I rejected some assemblies that had wires crimped into lugs and
> attached to a TO-3 case. The inspector had noticed that the wires were
> also
> tinned and then had been crimped. I said to rework based on the knowledge
> that
> we had never tinned wires to be crimped.
>
> But when pressed for the reasons behind my decision, I was stumbling for
> an
> answer. All I could come up with is that perhaps the crimp would be less
> crimplified (new word) over time due to solder creep or temperature
> excursions
> since the solder might reflow to some degree.
>
> What is the reason or doesn't it really matter whether tinned or not?
>
> Did this Quality lug crimp his position as the local answer man?
>
> Thanks to the forum,
>
> Stu Korringa
> Quality Engineer
> Smiths Industries Electronic Systems
> Grand Rapids, Mi.
>
>
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