Sunday, 22 December 2013

Self-adjusting crimping pliers for end sleeves from Knipex

Self-adjusting crimping pliers for end sleeves from Knipex
Also known as ferrules, cable end sleeves are very useful (necessary) when working with flexible electrical cables.

The main reason behind this being that flexible cables are made of many very thin copper cables which get crushed when screwed in a terminal. Using an end sleeve prevents tiny cable bits from falling off (and making a short...) while ensuring the best contact possible with the terminal.

Self-adjusting crimping pliers

Both self-adjusting an non-adjusting (cheaper) crimping pliers can be found on the market. Here are the reasons why I recommend the self-adjusting type:
A 'diaphragm' adjusts its size to match
your ferrule

  • Convenience: you do not have to worry about the ferrule type you're crimping. There is only one 'hole' in your pliers, you stick the ferrule in and close the pliers. This is much easier and quicker.
  • Electrical contact quality: since the pliers are self-adjusting, you don't need to worry about the pressure applied to the ferrule. It's going to be appropriate. If you end up with the wrong ferrule for your cable section (not recommended), you should end up with a cable properly secured.
Self-adjusting ones typically have a 'diaphragm' closing on the end sleeve (see picture on the left).

Number of crimping elements

Depending on the model, you might get different self-adjusting crimping techniques. The picture on the left shows the different models made by Knipex:
  • The 97 53 14 has six crimping elements making it my favourite (better contact?) your crimped ferrules come out in an hexagonal shape.
  • The 97 53 04 is a little cheaper than the 97 53 14 and allows larger cables (up to 10mm²) but has only 4 crimping elements producing square results.
  • The 97 53 08 and 97 53 09 have a frontal loading, which I find less convenient as it makes it harder to see what's going on (especially from one side ;-) The good point about the 97 53 09 is that it works with larger cable sections (up to 16mm²). These two also produce squarely crimped ferrules.
Bottom line: I personally prefer the 97 53 14 as I virtually never use 10mm² flexible cables and has an hexagonal shaped clamp. The only downside about these pliers is their price... but you get what you pay for: you'll have it for life (or at least that's what knipex's warranty says)
Different sizes of ferrules (end sleeves).
Both insulated and non-insulated versions exist.

Insulated vs. non-insulated ferrules

This is a matter of need and taste. I personally prefer insulated ones as they are both safer and easier to use: the insulation acts as a stop when inserting the ferrule in the pliers.
The only advantage I see about non-insulated ferrules is that they require less space to transport.
A non-insulated ferrule on
a flexible electrical cable

Crimping process

That's easy... 
  1. Strip the cable making sure the stripped length matches the length of the ferrule. 
  2. Insert the striped part of the cable in the ferrule and the ferrule with the cable inside in your pliers.
  3. Close the pliers.
That's it :-)