Micrograph analysis to check your crimping

As an expert in cable harnessing, MC Technologies offers you a micrograph analysis that allows you to have the quality of your cable harnesses checked. This way you can ensure that your connections remain reliable. We analyze the micrograph of your cables in a destructive process and give you alternatives on this basis in order to be able to achieve optimum crimping results.

A micrograph shows the crimp connection from the inside in cross-section. It documents the crimping result with optimum tool setting and serves as a reference for all further micrographs of crimp connections made with this crimping tool. A micrograph can be used to detect in advance whether there are any defects in the crimp connection.

The most common cause here is assignment errors between the conductor cross-section and the processable cross-sectional area of the crimp contact. The reason: Keeping stocks as low as possible and limiting the crimp contact variants lead crimp contact manufacturers to combine several conductor cross-sections into cross-section ranges.

Example: You have a crimp contact that is to cover a cross-section range in wire crimp of 1.5 to 2.5 mm². Then the crimp is optimal for a conductor cross-section of 2.0 mm². With a conductor cross-section of 1.5 or 2.5 mm², the crimp is just within the tolerance. In any case, not optimal.

The larger this cross-sectional range of the crimp contact is designed (e.g.: 0.75 to 2.5), the greater the risk that the wire crimp will be outside the permissible tolerances. Unfortunately, in practice the tolerances to be maintained are very often adjusted to the actual crimping result for cost reasons.

By analyzing the micrograph, it is determined whether the applicable quality criteria are met in production. The crimped stranded wire is clamped in the specimen holder of the cutting and grinding unit and guided precisely via a guide carriage onto the cutting wheel and then precisely onto the grinding plate. A color camera transmits the micrograph to a monitor. Using software, the micrograph can now be measured, stored and the measurement result evaluated.

Micrograph preparation as a destructive test is carried out on a random basis during ongoing production. The intervals depend on the quality standard.

A micrograph is required when:

• the manufacturer of the crimp contact and/or the conductor has changed.
• a certain number of crimps has been performed with one tool.
• the crimping tool has been disassembled during maintenance and/or repair.

• The originally round individual wires are deformed into irregular polygons.
• The crimp sleeve also has slight deformations on its inner surface.
• There are no cavities.
• The oxide layer of the individual wires is sufficiently destroyed.
• The individual wires break off irregularly during the extraction attempt.
• High conductivity.

Oxidation between the pressed individual wires is prevented and thus an increase in contact resistance is virtually eliminated. In borderline cases, small cavities may still occur in isolated cases. However, these can be considered self-contained due to the twisted conductor.

If you give us an order with such a combination where the crimping result is poor according to the micrograph, we will offer you alternatives as an expert with which you can achieve an optimum crimping result.