WIRE PREPARATION
MECHANICAL STRIPPING
two conductors, one stripped, the other in the process of being stripped
MECHANICAL STRIPPING

Mechanical stripping is an inexpensive, easy method of stripping most commonly used insulation materials and is the preferred methos for manually stripping film insulations such as Kapton®.

In the process, a grooved knife-edge is used to cut the insulation jacket down to the conductor. The severed insulation section is then manually removed without damaging the conductor.

See Section 1.01 "Wire Preparation, General Requirements", for common accept/reject criteria.
conductor with insulation jacket trimmed Kapton insulated conductor with insulation jacket trimmed

PREFERRED

GENERAL REQUIREMENTS
(ALL CONDUCTOR/INSULATION TYPES)

The insulation jacket has been neatly trimmed, with no edge flash and no mechanical damage to the conductor or insulation. Conductor stranding exhibits a normal twist pattern (lay).

PREFERRED

KAPTON® INSULATED CONDUCTORS

The insulation jacket has been trimmed neatly and squarely, with minimal edge flash and no mechanical damage to the conductor or insulation. Conductor stranding lay (twist pattern) is undisturbed.
trimmed conductor with acceptable edge flash trimmed conductor with unacceptable edge flash

ACCEPTABLE

EDGE FLASH

Edge flash shall not exceed one-quarter insulated wire diameter (1/4 d.). Edge flash is a thin layer of insulation that is produced during the stripping process, and is considered a contaminant.

NASA-STD-8739.4 [10.1.6]

UNACCEPTABLE

EXCESSIVE EDGE FLASH

The edge flash is in excess of one-quarter insulated wire diameter (1/4 d.), and may interfere with the proper completion of a crimped or soldered termination.

NASA-STD-8739.4 [10.1.6]
NASA WORKMANSHIP STANDARDS
NASA logo Released:
03.31.2000 		Revision:
B 		Revision Date:
07.03.2002
Book:
1 		Section:
1.02		 Page:
1




WIRE PREPARATION
MECHANICAL STRIPPING (cont.)
insulation jacket with slight scuffing insulation jacket with deep cut at location where it was trimmed

ACCEPTABLE

SCUFFED INSULATION/JACKET

Slight scuffing (a dull or rubbed appearance) of the insulation surface finish is acceptable, provided no other damage is evident.

NASA-STD-8739.3 [7.2.2]
NASA-STD-8739.4 [10.1.2]

UNACCEPTABLE

DAMAGED INSULATION/JACKET

The conductor insulation and/or cable jacket shall not exhibit any damage, such as nicks, cuts or charring. Conductors/Jackets exhibiting damage (other than minor scuffing) shall not be used.

NASA-STD-8739.3 [7.2.2], [13.6.2.a.1]
NASA-STD-8739.4 [10.1.2], [19.6.2.a.1]
smooth tool impression mark on conductor surface damage on conductor that exposes base metal

ACCEPTABLE

SMOOTH TOOL IMPRESSION MARKS

Smooth tool impression marks (slight cuts, nicks, scratches or scrapes) on the conductor surface, which do not expose base metal or reduce cross-sectional area, are acceptable.

NASA-STD-8739.3 [7.2.3]
NASA-STD-8739.4 [10.1.3]

UNACCEPTABLE

DAMAGE TO CONDUCTORS

Conductors that exhibit reduced cross-sectional area or exposed base metal shall be rejected.

NASA-STD-8739.3 [7.2.3], [13.6.2.a.8]
NASA-STD-8739.4 [10.1.3], [19.6.2.a.2]












NASA WORKMANSHIP STANDARDS
NASA logo Released:
03.31.2000 		Revision:
B 		Revision Date:
07.03.2002
Book:
1 		Section:
1.02		 Page:
2


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