problems crimping with yellow crimps, 6mm.

[HappyHippyDad]

This is only the second time I have had to crimp 6mm cable. I remember the first time a couple of years ago I had problems. Again this time the connection just pulled apart in my hands.

After looking through the forum I can see that others have had the same problem specifically with yellow crimps. 1mm and 2.5mm seem to crimp perfectly well (again seen in other threads), but with 6mm there is a problem.

The reason for this thread is because other threads point to the crimp or the crimping tool being the problem. I have a CK crimping tool which has good reviews and crimps 1mm and 2.5mm very well (I have tested these in a vice), so I believed the crimp to be the problem. I was about to buy some SWA crimps as other threads point to these being good quality. However, my red and blue crimps were bought from the same manufacturer as the yellow so it didn't really make sense that it was the crimp at fault.

I've just been in the shed crimping 6mm in a number of different ways and think I have found the problem. With red and blue crimps you have the crimp flush with the crimping tool when you crimp. I assumed it would be the same with yellow, however the crimping tool is wider for the yellow crimps meaning that when you crimp you are crimping the entire half of the crimp (perhaps even slightly over), meaning that you are crimping down on the piece of metal that sticks out in the middle of the crimp and I think this must be stopping the crimping tool from crimping properly.

The top crimp (see picture) was crimped with the yellow crimp (outer part) flush with the crimping tool and just pulled out easily. With the other two I slightly pushed the crimp into the crimping tool so that the central piece of metal would not be disturbed (you can see that the bottom 2 crimps have a bit in the middle still raised whereas the top one doesn't). I could not pull either of these out when placed in a vice.

Correct crimping is so important I thought I'd mention my little test. I tested the 2 ways each with 5 crimps and it was the same with all of them.

 

[Simonslimline]

I have to say that my daily ratchet crimp tool is CK and I have never had a problem with it. Still tight and makes a good compression every time. It is nearly 10 years old however and I do feel that CK tools in general were of a better quality some years back now. I had a set of CK drivers that lasted for years with daily abuse. I also had a newer batch that all shattered under normal use.

Seems to be the case with more than just tools these days unfortunately.

 

[Lucien Nunes]

I wouldn't be surprised that the first crimp is faulty due to the indentations being too near the centre. Part of the width of the counductor crimp zone is wasted on the endstop as you say, the remainder is on the very end of the conductors where the strands are likely to splay and escape, or even be forcibly ejected as the tube becomes funnel-shaped at the edge of the crimp zone. I would liken it to the very end of a conductor pinched halfway under a choc block screw.

I do also share concerns about the mechcanical durability of yellow crimps and the current rating of a completed joint relative to the size of conductor. I would only use products from a proper manufacturer with published performance and dimensional specifications and approvals. For critical applications as per Darkwood and Davesparks I prefer uninsulated crimps with a hex die - mechanically stronger, more consistent and reliably gas-tight crimp pattern and easier to inspect for successful installation.

 

[Skimpy Wan]

What do you recon to this as it seems reasonably priced (maybe too reasonably priced)...

http://pages.ebay.com/link/?nav=item.view&id=291059818578&alt=web

 

[telectrix]

i'vegot those same ratchet cutters. cost £60.brilliant.cut right through SWA inc. the steel armour. ( i done up to 16mm) . can't comment on the crimpers except seen then at elex and they looked a good piece of kit.

 

[Andy78]

What do you recon to this as it seems reasonably priced (maybe too reasonably priced)...

http://pages.ebay.com/link/?nav=item.view&id=291059818578&alt=web

These style of hydraulic crimper regularly pop up on eBay for about the £50 mark, but I have no idea of their reliability.
To put them in context though, I used to use a set of a very similar style and construction and they were spot on. A company I worked for bought them for a switch room job they had on at the time. The difference was that those ones cost £900 for the set.

 

[Skimpy Wan]

May give them a go then. The seller seems to indicate that they are ISO registered which means that their traceable items etc.
I need a new ratchet crimper for 10 - 16 mm crimps (which are £40 on their own) so not a bad offer if they work okay.

 

[Andy78]

May give them a go then. The seller seems to indicate that they are ISO registered which means that their traceable items etc.
I need a new ratchet crimper for 10 - 16 mm crimps (which are £40 on their own) so not a bad offer if they work okay.

If the largest you are doing will be be 16mm then a hydraulic set are a bit overkill. Why not get something a bit mechanically simpler. Less to go wrong with them then, especially being a budget product.

6-50mm² Electrician Cable Wire Crimping Crimper Hand Tool Pliers Ratchet Crimp | eBay

 

[Skimpy Wan]

I did see those, but thought they maybe a little too flimsy.

Mainly I just need 10 / 16 mm crimper as the bigger boy the boss has, so I get those when required (but handy to have my own for a later date).

 

[davesparks]

I have the same pattern hex crimpers as that, but from a reputable manufacturer rather than ebay

 

[Marvo]

The hydraulic crimper I have is by Hellerman Tyton, can't remember what it cost but I've had it a good few years and it's seen some action without any problems.

 

[shanky887614]

ive crimped loads with my cheap silverline and nno issues

 

[shanky887614]

If the largest you are doing will be be 16mm then a hydraulic set are a bit overkill. Why not get something a bit mechanically simpler. Less to go wrong with them then, especially being a budget product.

6-50mm² Electrician Cable Wire Crimping Crimper Hand Tool Pliers Ratchet Crimp | eBay

ive got them exact ones, here is a crimp cut open

 

[Skimpy Wan]

ive got them exact ones

Cheers dude. Were yours bought from flea bay as well? If so, can you let me know which seller you used and I'll see if I can get a pair from them as well (rather than using another seller / distributor where quality may differ?

 

[Skimpy Wan]

I have the same pattern hex crimpers as that, but from a reputable manufacturer rather than ebay

Out of interest, what make and how much are the pair you have Dave?

 

[Lucien Nunes]

here is a crimp cut open

Not sure about that pic, there seem to be voids between the strands and the tube. Makes me think the terminal was the wrong size for the cable or the die wrong for the crimp. Or is it not cut through the fully crimped section that was right inside the die?

 

[davesparks]

Out of interest, what make and how much are the pair you have Dave?

They are SWA, I bought them from the wholesaler years ago, I think they were around £50

 

[Marvo]

.....Makes me think the terminal was the wrong size for the cable or the die wrong for the crimp......

I think this is an inherent issue with the insulated crimps, the wire is rarely an interference fit into the crimp the way it is with an uninsulated type, hence the gaps. I think the insulated crimps try to cover several different wire applications like fine stranded, course stranded and even more than one wire CSA with the yellow ones which are rated for 4mm and 6mm in the same crimp. On the Maplin website it states 'The yellow types are suitable for cable from 2.5 to 6.5mm'........they're best left for work on cars and bikes in my opinion.

 

[davesparks]

To be honest these days I would be using wago connectors up to 6mm rather than crimps anyway, even in a car

 

[UKMeterman]

If you are using the bigger crimps say 2.5mm2 and up always remember I squared R is your enemy and so at higher currents say past 10 amps it is easy to show a mistake that causes a small increase in resistance will cause a big issue. For 6mm2 I would suggest remembering that the crimps and the crimping tool should be considered a matched set and come from the same manufacturer, this is in fact the rule at places like CERN who have had fires due to bad crimps and they have a lot of high current power supplies.

Crimp
34072 - TE CONNECTIVITY / AMP - CRIMP TERMINAL, BUTT, YELLOW | Farnell element14

Die
58423-1 - TE CONNECTIVITY / AMP - DIE, PIDG/PLASTIGRIP | Farnell element14

Tool
354940-1 - TE CONNECTIVITY / AMP - CRIMP TOOL FRAME, PRO-CRIMPER III,NO DIE | Farnell element14

 

[Skimpy Wan]

So rather than crimping to extend a circuit (I.e. 2.5 T&E) how would you recommend doing this - non-insulated / insulated crimps / solder (heat strink or not), connectors, wagon etc etc)?