CRIMPED
TERMINATIONS 简洁的描述 SHIELD CRIMPS 盾牌卷曲 |
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SHIELD CRIMPS Shield Crimps are used to mechanically "finish" the end of individually shielded cables. For
ground shield terminations, the crimp assembly will have a grounding wire
attachment, allowing the cable shield to be electrically terminated to
ground.
For floating shield terminations, the crimp assembly will be completed without the ground wire attachment. See Section 2.01 "Crimped Terminations - General Requirements" for common accept / reject criteria. |
ACCEPTABLE Outer
crimp ring has been deformed only by tool indenters, with indents properly
located and symmetrical. Inner crimp ring has not been deformed. No exposed
base metal. Ground wire has proper insulation spacing, and end is visible. NASA-STD-8739.4 [ 11.5 ] |
ACCEPTABLE Heat shrink sections are properly installed, tightly shrunk, and the termination is visible. Overlaps meet minimum electrical spacing. Ground wire exhibits proper bend radius and strain relief. NASA-STD-8739.4
[ 7.3.22 ], [ 9.8.1 ], [ 9.9 ], [ 11.5 ], [ 19.6.1 ] |
ACCEPTABLE Heat
shrink tubing is properly installed, tightly shrunk, and the termination
is visible. Overlaps are of sufficient length to meet minimum electrical
spacing. |
MANDATORY The end
of the ground wire shall be flush with the outer ferrule edge, but shall
not overhang the inner ferrule edge. |
NASA WORKMANSHIP STANDARDS | |||
Released: 03.30.2001 |
Revision: |
Revision
Date: |
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Book: 2 |
Section: 2.10 |
Page: 1 |
CRIMPED
TERMINATIONS SHIELD CRIMPS (cont.) |
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PREFERRED The ground
wire should be dressed to the rear of the crimp termination, to allow
the inclusion of a stress relief loop in the completed assembly. The ground
wire may also dress forward, provided sufficient stress relief is provided. NASA-STD-8739.4 [ 11.5 ] |
ACCEPTABLE The ground
wire insulation gap shall be < 0.76 mm (0.030 in.). The minimum
gap shall be flush with the edge of the outer crimp ring. NASA-STD-8739.4
[ 11.5 ] |
ACCEPTABLE The
inner ferrule may extend a minimum of flush with, and a maximum of 1.7
mm (0.07 in.) beyond, the front edge of the outer ferrule. NASA-STD-8739.4 [ 11.5 ] |
ACCEPTABLE Min.:
The placement of the crimp rings shall be such that the dress of the shield
stranding is not subjected to flexure stress or tensile load. NASA-STD-8739.4
[ 11.5 ] |
ACCEPTABLE Nicked
shield strands shall not exceed 10% of the total number of strands. |
UNACCEPTABLE The ground
wire end shall be flush with the outer ferrule edge, but shall not overhang
the inner ferrule. |
NASA WORKMANSHIP STANDARDS | |||
Released: 03.30.2001 |
Revision: |
Revision
Date: |
|
Book: 2 |
Section: 2.10 |
Page: 2 |
CRIMPED
TERMINATIONS SHIELD CRIMPS (cont.) |
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UNACCEPTABLE Improper
alignment of the ferrules reduces the reliability of the termination and
indicates the use of an incorrect crimp positioner, and/or improper insertion
into the crimp tool. |
UNACCEPTABLE The ground
wire insulation gap shall be < 0.76 mm (0.030 in.). The minimum
gap shall be flush with the edge of the outer crimp ring. |
UNACCEPTABLE Heat
shrink tubing conforms to crimp outline, but does not extend over the
wire to provide any sealing or strain relief. |
UNACCEPTABLE Wiring
must be properly dressed to ensure a reliable termination. Wire bends
shall meet minimum radius bend requirements. |
UNACCEPTABLE The inner
ferrule shall be sized so that the inward distortion caused by the crimping
process will not affect the insulated wires it surrounds. |
UNACCEPTABLE Nicked
shield strands shall not exceed 10% of the total number of strands. |
NASA WORKMANSHIP STANDARDS | |||
Released: 03.30.2001 |
Revision: |
Revision
Date: |
|
Book: 2 |
Section: 2.10 |
Page: 3 |
CRIMPED
TERMINATIONS SHIELD CRIMPS (cont.) |
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UNACCEPTABLE The shield
braid shall be dressed to provide uniform coverage and dispersion. Uneven
coverage may result in electrical interference in sensitive circuits,
and may interfere with the reliability of the crimp assembly. |
NASA WORKMANSHIP STANDARDS | |||
Released: 03.30.2001 |
Revision: |
Revision
Date: |
|
Book: 2 |
Section: 2.10 |
Page: 4 |