Basics of Reliable Wire Harness Production

Most of industries that require electronic equipment uses wire harness to keep different electrical wires safely on indoor and outdoor settings. Before the installation of wire harness within an electronic equipment, it has to satisfy use-case based requirements to avoid any damage either during the production line or at the field. Here, we cover some of best-practices and procedures that should be followed on cable assembly production to avoid such problems.

Sampling Procedure

To avoid any integration incompatabilities on production, a wire harness supplier and purchaser sides have to agree on a sample product and related technical drawing within a written -and signed by both parties, report that covers the information of used materials (such as terminal types, cable types and accessories), cable lengths, dismantle lengths etc. Consequently, it's better for both sides to keep replicas of this samples that had used on agreement to construct a common base on the product in between both sides.

Crimping Basics and Pull Test

Crimping is basically an integration of a terminal within wire. This operation can either be done within handtools (usually for sampling procedures) or machinery. Main crucial points to be considered are: Compatability of cable within terminal, compatability of crimping equipment within terminal and continous testing / maintanence of crimping equipment. An improper crimping operation may lead a break off of cable within terminal (due to damage by excessive force on crimping) or conductivity loss (due to oxidation in between copper strands).

Below, we show how good crimp and unacceptable crimp is from different angles.

An overview of good cable crimping picture from top view

Good Crimp. Insulation presents at point 1, conductor presents at point 2 and 3.

good crimp image, with proper shaping of barrels and conductors

Good Crimp: Barrels are closed and support each other.

bad crimp example due to excessive burr

Unacceptable formation with excessive burr due to improver crimper alignment.

bad crimp example due to improper crimp heights

Crimp height is too loose.

bad crimp example due to asymmetry of terminal

Asymmetric crimp due to incorrectly adjusted terminal.

bad crimp example for using large wire for crimp

Wire is lagre for crimp. Crimp barrels do not close.

bad crimp example for using small wire for crimp

Wire is small for crimp. Crimp barrels are too close to bottom.

To avoid such unacceptable crimps on wire harness production, pull test has to be periodically done (and recorded by) with a dedicated machinery. Besides, a visual test should be obtained on form of crimping material and formation of strands.

Electrical Testing

Generally, a wire harness has more than one branches -or ends- that may go off in a number of directions with several terminations on each branch. Here, a custom electrical testing for the specific harness has to be established and run to catch short connections or miswirings.

Hipot Testing

Hipot (High Potential) testing is a methodology to find insulation problems that low voltage testing can not. A damaged insulation or shielding may introduce a short connection (due to the relation in between magnetic fields and current in between conducted materials) even on non-conducting wires by high voltage. To avoid such cases on wire harness integration, a wire harness manufacturer should emulate the situation by same voltage level on harness with Hipot Testing equipment.