Crimping

Crimping has now largely superseded soldering as a method of making joints in electrical installations, and has proven extremely successful over the years since its introduction. A crimped connection is a permanent electrical connection between a crimp contact and a stranded or solid wire. Crimping involves the application of an external force (F), which deforms the individual strands of a copper wire in the tool plastically by stressing them to beyond the yield point of the material. This produces what is called cold weld. Automatic crimping machines are used in the wire processing industry to produce crimped connections automatically.

Wire, contact, crimping tool and tool setting have to be carefully matched to produce a high-quality crimped connection.

One process monitoring parameter that determines the quality of the crimping is the force needed to plastically deform the wire. Kistler offers various solutions to the problem of monitoring the crimping process.

Advantages of monitoring crimping process
The use of Kistler piezoelectric measurement for continuous monitoring of the crimping process offers the possibility of ongoing indirect checking of the long-term stability of a crimping unit consisting of drive, tool and material handling system. This ensures consistently high product quality (zero defect products). Eliminating the need for manual rejection of defective crimped connections also allows production costs to be lowered. And the process can be traced and documented.

The following defects can be detected by monitoring the force during the joining process:

• Broken individual strands in the copper wire
• Insufficient wire insulation stripped
• Dimensional discrepancies in connector
• Crimping tool wear
• Incorrect crimping height set on press

Direct or indirect measurement of crimping force
Depending on the mounting options, the sensor for measuring the crimping force can be incorporated into the plunger of the crimping machine in order to measure the full crimping force directly. Another generally very easily implemented alternative is installation in the base plate of the crimping tool, so that the crimping force can be measured indirectly (force shunt mode).

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