Illustration 1:

A connection for life: Crimping part 2

The first part of our blog introduced ‘crimping’ as a connection technique. In this part 2 we will delve deeper to help those who order parts and tools from Würth Elektronik achieve the best crimping results.

The crimping process:

1. The die is open. A connector is placed on the anvil. The wire is inserted by hand or by machine.

2. The descending crimper presses the wire into the crimp barrel and catches the crimp edge.

3. Subsequently, the crimp edges are rolled up, the Litz wire is evenly compacted and the crimp shaped.

4. The end position at the specified crimp height guarantees the required compression of the Litz wire into a virtually gas-tight crimp.

By following the steps correctly and properly inserting the wire, the result should be as illustrated below:

Problems that may occur during crimping

By not applying enough force when crimping or by using the wrong crimping tool, the wires could be insufficiently or incorrectly pressed. The resulting faulty connection increases the contact resistance between wire and crimp connection. Furthermore, there is a risk that an only partially pressed wire strands could be pulled from the crimp barrel.

On the other hand, a crimp connection must not be pressed with too much force either. Too much pressure or too small a tool could reduce the cross-sections of the finely stranded Litz wire to an invalid size. Furthermore, there is a risk that individual wires are sheared off if extreme pressure is applied to the finely stranded Litz wires. The reduced cross-section would decrease the current-carrying capacity of the connection. Moreover, the barrel of the crimp connector may become unusable due to cracks or breaks.

The insulation stripping process may also incur errors. The results of using unsuitable tools for the stripping process depend greatly on the skills and experience of the user.

Typical errors to avoid:

• The crimp barrel does not completely enclose the wire insulation

• The remaining wire insulation is damaged by the stripping tool

• Individual wire strands are damaged or cut off by the stripping tool

• Individual wire strands are retrospectively twisted excessively

• Individual wire strands are no longer twisted

• Connection is distorted

• Crimp tab is bent

• Connection is bent

• Wrong tool alignment

• Wrong selection of connection / wire cross-section

• Wrong crimp height

Illustration 2:

Quality control tests

Quality assessment and error indication: The crimp connection is checked using the pull-out force test. The wire strands should tear off unevenly (1), otherwise the contact is over-crimped (2) (which results in a predetermined breaking point) or not crimped enough. (3).

As a non-destructive test method, the crimp height can be measured. The crimp height and width are specified by the manufacturer of the crimping tool in consultation with the manufacturer of the connector. This test method offers the highest accuracy.

You can find a comprehensive overview of correct crimping connections here.

And finally, we wish you successful crimping!