Wiring and connectors

[Clive HartlandParticipant @clivehartland94829]

I have worked on mains electric kit that had to be used in a wet environment, I used adhesive heat shrink and had no leakage.

[SillyOldDufferModerator @sillyoldduffer]

Posted by bernard towers on 11/04/2022 20:09:57:

Temperature does not harden copper its movement (vibration) that does

Very likely vibration causes work hardening too, but I was referring to a form of Age Hardening where the application of heat below annealing temperature causes precipitation within the grain structure. Apparently it can happen at room temperature! The Copper's purity makes a difference, and solder compromises that by mingling Lead, Tin and whatever else in the Solder with Copper near the surface. Not the same as annealing, in which Copper is softened by heating well above soldering temperature and then quench cooling. The effect is small.

If work hardening due to vibration was the major cause of failure, crimped and solder joint would behave the same. They don't: vibrated soldered joints are more likely to fail than vibrated crimps.

Dave

[Michael GilliganParticipant @michaelgilligan61133]

Posted by SillyOldDuffer on 11/04/2022 22:16:35:

[…]

If work hardening due to vibration was the major cause of failure, crimped and solder joint would behave the same. They don't: vibrated soldered joints are more likely to fail than vibrated crimps.

.

Not quite true, Dave

… Your closing statement is valid, but the preceding sentence is not.

Peter’s explanation is good … at a micro level, vibration fatigue failure has a lot to do with the ‘stress-raiser’ created by filling the crimp with solder.

[stated from memory … If I can find corroboration, I will report back]

MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

This paper doesn’t actually address the specific issue under discussion here … BUT it is very informative, and I think the final image nicely illustates my point.

**LINK** : https://www.osti.gov/pages/servlets/purl/1356221

MichaeG.

.

On the other hand … here’s some evidence of ineffective crimping:

https://www.osti.gov/servlets/purl/1288669

Edited By Michael Gilligan on 12/04/2022 07:27:07

[martin haysomParticipant @martinhaysom48469]

it all comes down to the skill of the person doing the job soldering requires some. any fool can squeeze a pair of pliers

[noel shelleyParticipant @noelshelley55608]

Multi strand wire and fluids are never happy bed fellows ! Ask any one who had a Landrover TD5 engine ! engine oil would cappiliary from the engine to the computer under the seat along about 8' of wire. Noel.

[Tim StevensParticipant @timstevens64731]

A further factor is the attachment of the bullet (etc) to the insulation itself, and the nature of the insulation. Decent solder-type connectors (including bullets) include a clamp around the insulation of the wire. This is more effective if the clamping is done after the soldering has cooled – otherwise any clamp is filled with melted insulation which can be cut through. Yes, this does slow down the attachment process, but adds the stiffness of the insulation to that of the wire in vibration cases. In my mind, doing this sort of connection 'properly' is part of the discipline – it used to be called craftsmanship.

Modern harness wire for vehicles tends to be insulated with a stiff version of PVC – with less, or different, plasticiser. This results in a stiffer wire, and one of smaller diameter – easier to feed through small spaces. The behaviour of rubber insulation is quite different from this more-rigid PVC.

Regards, Tim

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