Ribbon wire fatigue

[Dougt115]

I am pushing the recommended design limit for bending radius on a ribbon wire and would like some information.

Does anyone have a graph of (bending radius)/ (wire radius) verses cycles for ribbon wires? Or some variation of this kind of graph. My tests are running from 1M to 4M cycles on a ribbon cable that should last 100M cycles, if I followed the manufacturer's guidelines (which I can't).

 

[btrueblood]

Is the cable metal fatiguing, or is the insulation wearing/cracking?

Most ribbon cable manufacturers don't design their basic ribbon cable for dynamic operations. You may want to look for and specify cables rated for "continuous flex" and/or intended for applications like robotics. Some examples:

http://www.alphawire.com/en/Products/Cable/Xtra-Guard-Performance-Cable/Xtra-Guard-Flex

http://www.heilind.com/products/molex/news/Molex_TempFlex.asp

http://www.hca.hitachi-cable.com/products/hcm/catalog/pdfs/Hitachi-Electronic-Catalog.pdf

(see pgs. 7, 19 "Hi Flex", pg 38)

You will need to dig deeper than those links to find recommended bend radii, expected flex life, etc.

 

[Dougt115]

Sometimes the wire sometimes the insulation. The wire is rated for 100M cycles just not at the bending radius that I am using.

 

[MikeHalloran]

>>> My tests are running from 1M to 4M cycles on a ribbon cable that should last 100M cycles, if I followed the manufacturer's guidelines (which I can't).<<<

You're painted into a corner.

Can you make room for a rotary transformer?






Mike Halloran
Pembroke Pines, FL, USA

 

[mcgyvr]

You just made your own "graph" by actually performing the tests yourself.. what more are you looking for.
You should contact the cable manufacturer to recommend a different cable or fix the improper design issue.

http://www.gore.com/en_xx/products/...le_hi_flex_apps_tech_background_document.html