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Nondestructive Crimp Verification

Summary: [This abstract is based on the author's abstract.]

Two methods are used for performing nondestructive verification of crimped contacts. The methods are crimp height and crimp indention check, using specific gauges and vernier calipers. The gauges offer a way to measure crimp indention of closed barrel contacts using four-point indention and eight-point indention. Points or anvils of the gauge are inserted into the indented areas, 180 degrees apart, to obtain the measurement. The values are compared to statistical analysis averages of measurement obtained via crimp indention performed on bare solid copper wire with the same outside diameter as the various contacts and wire used on a daily basis. Measurement of open-barrel crimped contacts is performed with a specific gauge that has one point anvil and one blade anvil. This allows measurement with the blade over the fingers of the contact formed over the stripped conductor. The point anvil is positioned on the flat area of the contact opposite the finger area of the crimp. Use of the point anvil allows measurement of potential "flashing" areas on the flat side of the contact. Terminal lugs are measured at the wire barrel area of both insulated and noninsulatated terminals. Tolerance allowances are higher with insulated terminals than noninsulated terminals because of the recovery of the insulation material. Measurement is performed using vernier calipers, using only the ground area of the blades. Values on terminal lugs are compared to statistical averages taken over time of actual crimps on terminal lugs. The methods described allow retention of wire and contacts for use in the given product. In other methods, the disposal of samples would be required for evaluation through destructive pull testing.

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  • Topics:
  • Keywords: Verification, Measurement and control, Testing, Nondestructive Testing (NDT), Gauges, Tolerances
  • Author: Simmonds, James, R.
  • Journal: Quality Engineering