Sealing a cable in a connector 1

[zandbj]

Hi,
I have the following challenge. I need to seal 3 to 6 mm cables in a 6.5 mm hole. There can be different jacketing materials on the cable PVC, PUR or Low smoke non halogen jackets. The seal has to meet IP65 (dust and water resistant) . be as chemical resistant as possible and should act as strain relief. I'm looking for an adhesive that can do the trick instead of the common rubber washers and mechanical strain relieves.
It should set as quickly as possible. Ones the cable is fixed it's fixed so no need to ever remove it ever again.
Any ideas or leads would be very welcome. I'm thinking like a PUR foam or a Intumescent material but have little experience with these materials and a problem where to start. So all help welcome

 

[MikeHalloran]

Please refrain from duplicate posts; the people you need will find you.


Mike Halloran
Pembroke Pines, FL, USA

 

[SwinnyGG]

Pot the connection with epoxy.

Cheap expanding foam from a can is not the least bit chemical resistant, has very little mechanical strength (i.e. will not provide much strain relief) and doesn't really bond to anything- from what I can tell it stays where it is put based mostly on mechanical forces. It would be a very poor choice for potting connectors.

 

[winstonsk]

second the epoxy suggestion. Just be sure to clean the surfaces you're potting well to improve adhesion or else you'll get leaks over time. also be aware of the amount of shrinkage you'll encounter when the epoxy cures.

the only other options that I can really see are some kind of through-pass connector.

 

[MintJulep]

Adhesives will not adhere well to most wire insulation materials. Especially not to the low-halogen insulation which tend to be polyolefin. The motion from the desired strain relief feature will cause whatever slight bond you do get to fail.

Use one of the proven mechanical solutions from a supplier such as

http://www.heyco.com/index.cfm.

 

[KENAT]

Potting with epoxy can probably be made to work if other requirements force the issue. We've done similar on glove box feed thrus. Heck, we've even had mesh covered wire bundles/cables where we have to fill a section of the cable with epoxy using a syringe and then potted that into a feed-thru!

You may need to do a surface treatment of the cables depending on insulation material as Mint says - there are primers for PTFE etc. or else slight mechanical abrading and really good cleaning with suitable solvent (e.g. Acetone or...), with finish clean with IPA or similar to remove solvent residue will probably allow reasonable adhesion.

There are some epoxies with reasonable chemical resistance, I think I've posted related questions or responses before if you hunt.

We've spent quite a bit of time (i.e. company$) investigating chemical (especially solvent) resistant epoxies and I'm afraid I cant' just give that info away but will give some hints.

Vacuum epoxies like Torr seal (or the unlabeled loctite equivalent) is our base line for chemical compatibility - it does reasonably well and is more readily available than some more exotic formulas. Also can be used without heat cure - some of the fancier epoxies may require relatively high temp cure for best performance.

Some of the 'high temperature' adhesives from places like

http://www.masterbond.com/properties/chemical-resistance

have better chemical resistance - if you pick the right ones. Chemical and temperature resistance both depend on the length of the ethane chains or something like that (I ain't no chemist).

Epoxy is used to coat solvent tanks etc. on trains so consider looking at coatings not just adhesives - adjust cure time etc. accordingly.

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