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Crimping tools with a spring effect

Within every production process, there can be deviations in the final product. The same is true of conductors, which also have a tendency towards an increasingly narrow design. Crimping tools with a spring effect enable reliable compensation of potential size discrepancies between the conductor and the wire-end ferrule.

 

Generally speaking, two components are permanently connected to one another during the crimping process. According to the three functions – namely cutting, stripping and crimping – a conductor end can be crimped with the corresponding contacts or wire-end ferrules after stripping. In the past, conductors and contacts were securely connected by way of soldering; in the meantime, crimping has largely dislodged soldering as the

preferred method. The homogenous, non-detachable connection between the conductor and connection element is correctly established during the crimping process using a crimping tool.

In principle, there is a multitude of mechanical crimping tools available on the market. They facilitate, simplify and secure the handling process, offer an integrated restraint lock featuring an unlocking option and guarantee optimum processing quality. Generally speaking, the range of crimping tools on offer can be split into those for wire-end ferrules and those for other contacts – such as for cable lug-sleeves and cable-lug connectors with a rolled-up crimping claw, for PVC-, PC- and polyamide-insulated connectors, for bare cable lugs and connectors, for fibre-optic cables, for coaxial connectors such as BNC, TNC and N connectors, and for sub-D contacts. Pressing tools or special crimping tools, meanwhile, are used when handling special cables and/or lines.

One current example of a crimping tool with a spring-loaded effect is the PZ 6 Roto L
The right combination produces a good crimping result
The nominal conductor cross-sections are not always complied with: they sometimes only measure 2.8 mm² instead of 4 mm²

Given the diversity of cables and lines, the call for every combination of conductor and crimping material to be applied with one tool was impossible to satisfy. Also, we didn’t choose the cheapest or most expensive tool over the connection quality; we opted for the right one instead. Manufacturers who have many years of experience and are familiar with the material cover a certain range of applications with one tool, or integrate various functions in one device.

 

During the selection process, it must also be borne in mind that, even if conductors and crimping materials satisfy the applicable standards by themselves, this does not mean that the crimped product meets the standards' requirements. After all, the individual production tolerances of conductors and crimping materials do not enable every conductor to be

processed with every contact. Therefore, the combination of conductor, crimping material and crimping tool must always match, which is complicated by the high number of products available on the market. The material has to be defined and the crimping result tested accordingly. It must always be ensured that testing and subsequent tool use satisfy the same conditions, which is why DIN EN 60352-2 recommends sourcing tools and contacts from one manufacturer. Only in this way can a consistently high level of quality be guaranteed.

Neat crimping despite an insufficiently accurate fit

One source of error that should not be underestimated during crimping is the tendency towards increasingly narrow conductors. In this regard, Weidmüller offers crimping tools with a spring-loaded effect.

We are now determining an increasingly clear development – that conductors' nominal cross-sections are often not being complied with. Over the last few decades, conductor material has been subject to ongoing optimisation, such that the required conductivity is also specified if material is saved. So it's not really an issue per se. However, the problem arises during processing with wire-end ferrules. If the ferrule originally designed for the nominal cross-section no longer fits the conductor, the crimping dies must compensate for this size discrepancy. This certainly isn't an easy task if the conductor in fact only measures 2.8 mm2 instead of the stated 4 mm2, for instance. To compensate, it is advisable to use crimping tools with a spring-loaded effect.

 

In the case of the spring-loaded tools, two forces work together with

In practice, the size discrepancy between the conductor and wire-end ferrule leads to challenges in secure crimping

great precision: as soon as the potential of the omega spring has been exhausted, the shear spring takes over. In this way, the suspension is sufficiently extended to neatly crimp conductors and wire-end ferrules with one another, despite an insufficiently accurate fit. Essentially, Weidmüller uses metal instead of plastic as the material for the spring-loaded elements in manual tools. As the spring performance is incapable of influencing even extreme external temperatures in this way, we are relying on a neat crimp connection in different industrial sectors and climate regions.

Crimping with a spring effect – even when things are getting tight

One current example of a product with a spring-loaded effect is the PZ 6 Roto L. Featuring the rotatable crimp insert, the tool can be used as the available space permits, since conductors and wire-end ferrules can be inserted both from the front and the side of the tool. The lockability of the crimp insert combines the benefits of a fixed and a rotatable tool, so users remain flexible in their applications. Since conductors and wire-end ferrules can be crimped with a single tool across the entire cross-section range from 0.14 mm² to 6 mm², the time-consuming process of changing tools is rendered unnecessary – and reliable crimping results are achieved at all times thanks to the spring-loaded effect.