Mail*Link(r) SMTP               FWD>Ass: Cable Assembly Destructive Testing

Moss,

When we got into revising our electrical/electronic cable and electrical
termination specifications, we determined there are two different "general"
standards.  One is based on the USA's DOD Mil Spec's, the other is based on UL
(Underwriters Laboratories)  The following are extractions of their
requirements:

Wire Gauge   Crimp Tensile Strength (minimum) N [lbf]
(AWG)            |_Mil Std__|____UL_____|
26               |  30 [ 7] |-----------|
24               |  45 [10] |-----------|
22               |  65 [15] | 35.6 [ 8] |
20               |  85 [19] | 57.9 [30] |
18               | 170 [38] | 89.0 [20] |

At the time, UL didn't recognize wire gauges less than 22 for electrical
wiring purposes.

Final general comment on crimping.  Crimped tensile strength is a "skewed" to
the right "bell-like-shaped" curve.  The UL tensile strength requirements are
all below the "maximum peak", if the crimp is "under" crimped, the wire pulls
out; if it is "over" crimped, the "crimp strength" in increased.  Mil Std's
are crimped close-to or slightly over the "max" tensile strength on the
"downward" slope of the curve.  Therefore, an "under" crimped Mil-Std results
in a "stronger" joint, an "over" crimped Mil-Std results in a lower strength
joint.  There is little variation in the  "conductivity" or "resistance" of
crimped UL or Mil Std electrical terminations according to both literature and
our testing and experience.

Ralph Hersey
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--------------------------------------
Date: 9/4/96 11:46 AM
From: Maurice Dore *

Can anyone suggest specs for Cable Assembly Destructive Testing, 
specifically
for AWG No. 22 (CSA mm square) wire and crimp connection tensile strengths.
Thanks in advance.

Moss Dore
AMT Ireland
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