HI all,

I hope we may have some electrical QA people here that may be able to offer some advice. I am not an expert in all things related to crimping of electrical terminals (still learning!) but I need to accept or reject a product.

It has arrived at us with the terminal crimped as per the attached. We have been having issues with the supplier getting these crimps correct, with some very obvious poor practice in the past (crimps falling off in the box!). This latest reiteration has seen them tin the conductor strands before crimping the terminal on.

We are concerned that this is not good practice, as it relies on the tinned strands being central in order to maintain continuity. I've not seen it done like this before and wanted a second opinion.

It passes a reasonable pull test.

Hope someone can give their opinion.

I hope we may have some electrical QA people here that may be able to offer some advice. I am not an expert in all things related to crimping of electrical terminals (still learning!) but I need to accept or reject a product.

It has arrived at us with the terminal crimped as per the attached. We have been having issues with the supplier getting these crimps correct, with some very obvious poor practice in the past (crimps falling off in the box!). This latest reiteration has seen them tin the conductor strands before crimping the terminal on.


It passes a reasonable pull test.

Hope someone can give their opinion.

It appears to be that the crimp area is too big for the size wire. I think they may be trying to accommodate that problem by tinning the parts to add some strength and volume to the wire prior to crimping. Generally, a good crimp should compress the strands until each conductor is fully in contact with adjacent conductors and slightly deformed. That gives maximum strength and continuity. If your circuit is not critical - such as an LED light or something, it may be OK. If it is a control circuit, I would not be impressed with this. I would also cross-section the crimp about midway to determine the crimp quality. That inspection is rather common for high quality crimps. Pull tests only tell you if you have horrid crimps. Bad crimps can still pass pull test. It is a relatively pitiful test.

HI all,

I hope we may have some electrical QA people here that may be able to offer some advice. I am not an expert in all things related to crimping of electrical terminals (still learning!) but I need to accept or reject a product.

It has arrived at us with the terminal crimped as per the attached. We have been having issues with the supplier getting these crimps correct, with some very obvious poor practice in the past (crimps falling off in the box!). This latest reiteration has seen them tin the conductor strands before crimping the terminal on.

We are concerned that this is not good practice, as it relies on the tinned strands being central in order to maintain continuity. I've not seen it done like this before and wanted a second opinion.

It passes a reasonable pull test.

Hope someone can give their opinion.
Seems to me that the barrel size is bigger to the wire size that is used as I have a close look at the attached pic. Tinning is not a normal practice for such terminal barrels. (crimps falling off in the box!). ... seems to support what I feel. The single best indicator of a good crimp is the pull force test done with only conductors crimped. Crimping is indeed a special process and needs to be validated. I would suggest a relook into the terminal selection for the wire in use. Molex site gives lots of value added information on crimping and crimp inspection.

I suggest you go to the manufacturer of the connector for guidance on what thye percieve is a good crimp.
I wish I could post a link but am unable to do so, but use google for searching 'F' crimp specifications and I am sure that Molex, AMP and others will be linked to give similar guidance documents to use.


Having worked for a cable/wire company for many years I agree that a pull test is not the best test. Looking at the result it would appear that the specification is for an incorrect wire gauge. The insulation crimp is good but the wire crimp is for a different gauge. There will be alternates in the suppliers catalog.

Do not risk the safety of end user by using incorrect components.

Thanks guys for all your input.

We agree at this end with the comments regarding the terminal barrel being too big for the cross sectional area of the terminal. This was just a sample, so we can go back to the manufacturer and request the use of a smaller terminal.

I will also try and convey further points to them regarding the quality of their crimps. The molex site does indeed look like a good source of information.

Thanks :)

Can't really add much to what's already said since it is pretty much dead on. I've attached a PDF (compliments of Tyco's website) as a resource though.

Wayne

Some very good comments posted.

The terminal is indeed too big for this specific wire, but is also a bad crimping because has a wrong bellmouth - is in front of the terminal. A good crimp has a small bellmouth at the beginning of the terminal(to the wire insulation side ), If the bellmouth is missing there is a big risk of cutting the wire strands, and the terminal can become loose.

One more comment - I have seen strans which are tinned after the crimping was performed, but not for this type of terminal.

Alin

Never tin wire crimps. They eventually loosen due to the solder creeping.