Crimping

CRIMPING

Crimping ensures electrical and mechanical connection of the wire to an item of equipment or to a connecting system by means of the end fitting.

Crimping Tools
Special crimping tools are needed to crimp a connecting device onto a wire. A properly crimped terminal provides a joint between the wire and the terminal as strong as the wire itself.
The preferred crimping tool is a ratchet-type crimper that is periodically calibrated to ensure a consistent and proper crimp. When using a ratchet-type crimping tool, the handles of the tool will not release until the jaws have moved close enough together to properly compress the terminal barrel.
Many crimping tool manufacturers are available (AMP, Buchanan, Burndy, Cannon, Daniels, Hughes, Raychem, etc.), who provide different types of crimping tools to be used with different types of connecting devices. Some have fixed locators, and the tools come in different sizes indicated by the color coding on the handle. Some tools have removable dies with different part numbers for different connecting devices. Another type has an adjustable locator.

Hydraulic Crimping Tools
Hydraulic crimping tools are often used on wire gauge sizes 0 through 0000 because of the force required to properly crimp the wire. Like the ratchet-type crimper, a hydraulic crimper must be calibrated periodically. 

Testing of crimping tools:

Test intervals

  • Each new tool before use shall be submitted for gauging, where applicable, and specimen checks.
  • Each tool shall be submitted for gauging at 1000 and 2000 crimps and only if successful, returned for use. The checking at 3000 crimps shall be by gauging and specimen checks. This procedure shall be followed at subsequent 1000 crimp checks.
  • All tools not in regular use shall be similarly checked every 12 months to the gauging requirements.
  • When a tool becomes due for a 1000 crimp or yearly check it shall not be used again, until the results of the test interval are known and the tool certified for use.

Gauging of tools:
Each tool or die shall be tested by the insertion of GO/NO GO gauge.
When tool handles are squeezed, the GO element must pass through the dies, the NO-GO element must not pass.

 

 

TESTING OF CRIMP JOINTS
Pre-crimping checks
1. Wire shall be correctly stripped. (See Wire Stripping)
2. Check correct combination of cable, tool, terminal end or connector.
    a) Crimping tool and locator shall be correctly selected
    b) Before use, every tool shall be checked for:

  • Identification (Tool Serial No.) with its own particular history card. (Tool used will not
  • have exceeded 1000 crimps on an interval of 12 months without being tested, unless otherwise stated)
  • Cleanliness of die faces.
  • Freedom from damage.
  • Freedom from corrosion.
  • Freedom from wear. (Tools in regular use shall be cleaned daily to avoid buildup of dirt and plating on die faces and care shall be taken not to damage the die faces.)

Post-crimping checks
All crimped joints shall conform with the following visual checks:

  • Correctness of form and location of crimp.
  • Freedom from facture and rough or sharp edges.
  • Burrs are inherent in some forms of crimping.
  • These burrs should not be excessive to the extent that they cannot be removed without the use of a tool.
  • Crimping indents away from inspection hole
  • Crimping indent correctly centered on the barrel.
  • No damage caused on the attaching system, or to the
  • male contact pressure system (removable contacts).
  • Acceptable geometrical distortion, correct die mark.
  • Wire visible through inspection hole, if applicable.
  • Position of insulation after crimping (see Figure).
  • Position of wire after crimping (see Figure).
  • No strands outside the crimping barrel (and/or extending out the inspection hole).
  • No cut strands
  • Adequate insertion of conductor strands in barrel where it is possible to check without damaging conductor.
  • Absence of damage to the conductor. 

 

On completion of the crimping operation, the wire insulation must not be pushed back out of end fitting and sealing system. 

 

The distance between the crimping barrel and the wire insulation must be less then 1mm. 

 

 In specific cases where, by construction, the distance between rear face of the hard insulation is less then 3mm, this value is brought to 0.3mm max.

 

The maximum distance tolerated for the extension of the wire core out of the crimping barrel, connection side is 1.5mm. 

 

Note: It is recommended that each crimp has a gentle manual pull applied in order to establish there is no movement of conductor within the crimp. A crimped contact is shown below.

 

 

 

 

 

 

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