Insulated crimp terminal diameter issue, KNIPEX / Molex / TE / AMP

[mzzj]

I'm with Bent on this one, this based on a long career in industry.   The crimps that even brand new crimpers, for insulated terminals, produce are terrible.If yu have to use crimp terminals you are far better off with non insulated ones and a crimper designed for them.

Define  "terrible"
Sounds like you got either mismatched tool/terminal set or low quality terminals. No-name cheapos can be anything (or "budget line" brand names)
Same applies to fold-tab or F-crimp terminals..

I was curious how good the Abico terminals sold on local "auto store" are and tested the crimps with fishing scale and bucket of weights.
Crimped with the cheap knipex clones the pull-out force on 1.5 mm^2 wire exceeded the military standard requirement (50 lbs for 16 AWG)
https://www.cirris.com/learning-center/general-testing/special-topics/228-crimp-pull-testers-pullout-force-per-wire-size

OK, wire was slightly oversize (16 AWG vs 1.5 mm2) but still  ahead of the "commercial" standards.
AFAIK automotive USCAR-21 standard would satisfy with 170 N or ~38 lbs

[2N3055]

I have given up looking at the color codes a long time ago. I make a test crimp and if I can pull the wire out then I use the smaller opening.

This. Same here.

And Molex are assholes, with their 500000 USD custom crimp tools...
I suggest you change title. Knipex is at no fault here. It's Molex that is not standard.
I use Knipex and Pressmaster and they are both excellent.

[iroc86]

And Molex are assholes, with their 500000 USD custom crimp tools...
I suggest you change title. Knipex is at no fault here. It's Molex that is not standard.
I use Knipex and Pressmaster and they are both excellent.

Haha yes, I do question Molex's motives when they sell a single $500+ crimp tool that's designed to crimp one part number. That's what turned me on to TE/AMP and their PIDG stuff--slightly more expensive than Molex, but the tooling standardization is definitely worth something (especially in a DIY/hobbyist capacity where one cannot afford a dozen different crimp tools).

I updated the title per your suggestion to capture the other brands.

Out of curiosity, would you mind sharing the KNIPEX tooling you're using for crimping?

[mzzj]

18 AWG wire+ chinesium crimpers + Abiko terminals:
https://imgur.com/a/JRrsZQS

Crimping action is pretty stiff and crimp anvils wont reach each other. Looks like even the wire insulation stripped off.

[2N3055]

KNIPEX 97 52 36 for insulated terminals. For others I use Pressmaster modular..

[Gregg]

I see no reason not to use the indent type crimpers on the plastic sleeved terminals.  I mainly use the Thomas & Betts or Klein for the red and blue ones and a bigger dimple crimp on a pair of Klein pliers for the yellow.  For larger terminals, hex crimps are the best I’ve found.
The double half-moon type crimpers for the plastic sleeved terminals are a crapshoot as far as them passing the tug test.
https://www.alliedelec.com/product/thomas-betts/wt111m/70039935/
https://www.amazon.com/Insulated-Non-Insulated-Klein-Tools-1005/dp/B0006M6Y5M
https://www.kleintools.com/catalog/high-leverage-connector-crimping/linemans-pliers-crimping-9-inch

[iroc86]

mzzj, by the looks of those crimps, I bet my KNIPEX dies would work with these PIDG double-walled terminals. They measure about 5.7 mm on the OD, just a hair smaller than the 5.8 mm Abikos you described in Post #5. It looks like you're still getting that secure squashed/bulging effect on the insulation, even though the Abiko dies look quite a bit different than my TE/AMP tool.

2N3055, thanks for sharing the KNIPEX tool you're using. I bet the geometry is identical to my Crimp System. What brand of terminals do you prefer?

Gregg, do you have any issues with the insulation sleeving breaking with the dimple crimpers?

Interesting discussion on the dimple-type crimpers. I have the KNIPEX 97 49 14 dies (shown below) which are intended for non-insulated tubular terminals per DIN 46234 and 46235. These do not produce an F-crimp. I've used them on Molex Krimptite with success, but I think they might work best with brazed seam terminals due to the crimping forces involved (no splitting of the seam). Panduit, however, notes in their application guides that you can use either type of seam with their tool, just align the seam opposite the indentor. Any real world experience on that one?

[Gregg]

I haven’t had any problems with dimple crimps removing the plastic sleeves on reasonable quality terminals.  Sometimes the plastic will become a little loose with the barrel to wire connection very secure; the plastic sleeve really doesn’t do much unless there are multiple connections close enough that they might short without it.  Mainly it covers up strands of wire that a lazy tech didn’t get into the crimp barrel and makes an installation “look pretty”.
I was on a big job years ago installing hundreds of control wires and a co-worker had the company buy a couple of the expensive double half-moon ratchet crimpers.  I used my own crimpers and was told they weren’t “certified for the terminals” being used.  I then grabbed a bunch of his crimped terminals and gave them the tug test – a quarter of them pulled right off.  These were the red Thomas & Betts terminals 16 to 22 ga rated being used with 20 ga stranded TFFN wire and a Thomas & Betts crimper.

[mikerj]

I tried those connectors out 25 years ago. They were useless then and they're useless now, no matter which brand or crimp tool you use.
The idea/design is faulty from the start and no serious engineer would ever use them.

Functioning crimp connections use the "4-tab fold-in" design, like these:

Insulation is done with tailored sleeves or heat-shrink tubing.

There are millions of these terminations in track side railway signalling equipment all over the world.  I spent several years working for a company building these racks, and sectioned test crimps and wire pull tests were performed daily for each tool used.

I'm sure you're right. But that's a static installation with no mechanical stress.

Track-side equipment is subject to fairly heavy vibration.  It's also a safety critical application, if these terminations were as bad as you say then they wouldn't be used.

[Doctorandus_P]

There is also a lot of quality difference in the crimp connectors themself.
The cheap ones are just made out of stamped sheet and the tube for the wire is open.
On high quality crimp connectors there is a piece of tubing between the stamped connector and the plastic sleeve.

Apart from that.
The whole concept is inherently flawed. Crimping metal connectors through soft plastic is a shaky recipy.
It can be made to work, but to make it work well you will need tight control of tolerances and materials of both pliers and the connectors themself.

[iroc86]

It can be made to work, but to make it work well you will need tight control of tolerances and materials of both pliers and the connectors themself.

Based on what I've seen and learned in this thread, that really does sound like the clincher. There's definitely some overlap between manufacturer's crimping dies where the insulated terminals can be made to work, but if I were working on any mission-critical application, pull and endurance tests are probably the only way to be sure the crimp is acceptable.

Yesterday I was checking out a friend's private airplane. Lo and behold, there were double-walled insulated crimp terminals all over the place. I doubt the (U.S.) Federal Aviation Administration would sign off on the use of these terminals if they weren't reliable, especially considering the prevalence of required backup systems and fail-safes in the aviation industry.