Re: What to use as crimp tool?

Actually, crimping properly done does not need soldering. Properly done is the hard part. There is some serious materials science to know.

so hot they

method.

It depends, i have seen crimps handle 1000 A gracefully. I have seen crimps in benign environments die at mA. If a crimp is getting warm it was improperly done. Soldering does not really help correctly done crimps, only marginal ones. Unfortunately that does seem to be the vast majority of them.

Just plain wrong. Good crimping _DOES_ require proper training, an element most sorely lacking today.

That is your choice. Make it with my blessing. None the less, you are in error, soldering a correct crimp decreases reliability. Soldering a marginal crimp does increase reliability, but why are you putting up marginal crimps?

So can crimping. You just have to know how to inspect it. Good crimping is a bit esoteric. If it was not reliable the US military and NASA would not have kept using it for decades.

Like i had stated before, poor crimps may profit, good crimps lose.

Nobody could tell me how to do the training needed nor how to do the inspection needed. The expensive tool was bought. It was a recomended one. The person used as the maker of the tool said to. The crimps failed in the field. Soldering solved the problem. When we soldered the crimps the failures stopped dead.

I put up witht he marginal crimps because nobody can tell me how to tell the difference between a marginal one and a nonmarginal one. The only way to tell was to wait for them to fail.

When they got soldered, the reliablitiy was 100% in that we didn't have a single failure after that. We had a set of instructions that could be followed and the joint could be inspected so we had what we needed.

On Apr 20, 9:33 pm, JosephKK wrote: [...]

As I pointed out earlier:

(1) A properly done crimp never fails.

(2) If it never fails it is properly done.

I need a way to tell the proper ones from the nonproper ones that doesn't involve waiting for them to fail. I need a procedure that leads to no failures.

Without soldering the crimp lugs, I had neither.

Its easy to look at them, you just take it apart. Maybe a MRI or CT scan, PET ?

greg

I find myself in the same position with some SE Asian suppliers.

You can specify on paper till you're blue in the face, but they'll still make substitutes to reduce cost in the initial evaluation stages. If you catch these early, and detect potential trouble, I find that the resulting product will generally tow the line in production shipments.

I have no problem with modifying drawings, adding alternates to reflect the source's capability, providing the product proves functional and accurate info on the subs made is provided for the docs, prior to finalizing the sale. This is normally needed for safety documentation accuracy, anyways.

Maybe next time, eh?

RL

If basic disassembly/inspection and performance is inconclusive, a simple microsection of samples (failed specimen, unstressed suspect specimen and reference specimen) isn't out of the question, pricewise.

RL

(2) should be "If it fails, it was not properly done."

It is possible for improper crimps not to fail.

I agree on not needing the soldering.

Since we are talking about evaluating alternates, I believe it should be "toe the line".

That alternative does not always result in timely completion of a project, within budget. Intelligent flexibility, properly supervised and documented, can be a profitable characteristic of part sourcing activity.

These guys are simply trying to do their job - if you can help them succeed, it can only contribute to your own success.

RL

Hear hear..

Soldering cables in moving equipment (cars, motorcycles etc) will cause vibration induced failure.

After you've sectioned a crimp lug, it is no longer useful. You now have a crimp lug that you know about and a bunch of others you don't. You would only be further ahead if what you learned from sectioning could somehow let you fix the process and find a way to nondestructively inspect it.

The non-failed one would have to be one taken back from the field after years of service since until it has been in service the best you can say is "it hasn't failed yet". You can't say it won't fail in service unless (A) there is a nondestructive test we could apply or (B) it has been in the field. This leads to the problem that we would have to experment on our customer or not ship product.

Once you know what internal detail makes the joint not fail, you then need to create a process that produces this internal detail without fail in 100% of the cases and a way to inspect to see that this process was followed.

You could do all of the above eventually or you could solder it right now and solve the problem and ship product that will work in the field. I choose to solder the crimp lugs.

If you use asian manufacturers, you have to be willing to send someone there to look at them. The same applies to Mexico, Europe, or the shop next door. You have to show that you care enough to show up. Once you have them convinced, you have to keep them convinced. You also need to be willing to reject batches. If they can shift the cost of monitoring quality to you, they will. Rejecting batches on the "there was at least one bad one in the batch" basis pushes the cost of insection back onto them.

Since 100% of the failed connections were the ones that were that were not soldered, and I had zero failures on the soldered crimp lugs, I will continue to solder them.

I can visually tell if a lug is soldered. I know that if it is soldered, it won't fail so the problem is solved so long as I continue to solder them.

I have built stuff that goes in helicopters. Caterpiller makes earth moving equipment. Both are high vibration environments. Other equipment is shipped around on trucks which is a slightly lower vibration environment.

If you allow flex to get to a crimped electrical connection it will fail. You have to strain relief all electrical connections no matter how they are made.

Try searching for a NASA certified crimping school. When i completed my course i NASA ground support qualified at solder, wire wrap and crimp. That was a long time ago, about 30 years. Two weeks of 8 hours a day.

Actually there what is called go / no-go test tools that verify the crimp tool is setup properly. There are post crimp gauges that can detect most bad crimps. And the expensive way is with micro focus X-ray, but it provides the best results.