Nylon connector torque degradation over temperature

[Jon5]

I have a nylon panel mount connector that, when heated to our upper temperature limit of 85°C, suffers from significant torque degradation (from 6 in-lbs to 1 in-lbs).

I am trying to work with the vendor to spec a new material for the connector that will not yield as much under thermal loading and will retain its original torque.

I need to find a new plastic material that will hold up to the temperature and will also be fairly compatible with the existing injection mold tooling designed for nylon.

For example, Ultem will likely meet the thermal requirements but due to shrinkage factor of the material it would not be appropriate for the current mold.

Anyone ever swap nylon for a material with a higher HDT using the same tooling?

Thanks

 

[Compositepro]

PES(polyethersulphone)maintains its mechanical properties pretty well at temperatures above your requirements.

 

[unclesyd]

If your supplied can't provide a filled nylon that meets your mechanical requirements I would try Ryton (polyphenylene sulfide) from Phillips Petroleum.

http://www.cpchem.com/enu/ryton_pps.asp

 

[Pud]

What is the current nylon?

If it is Nylon 6, then yes, 85 deg will not be OK.

Cheapest route - nylon 6.6

Next: PBT (polyester) - good for 100 continuously.

PPS requires tool surface temp to be at 135 Deg C minimum to achieve required crystallinity - otherwise do not bother - can the tooling/moulder do this? (unlikely if tool made for PA6)

PES is way over spec (and over priced) for this - processing window very small, if you include drying requirements, etc.

See

http://www.distrupol.com/en/info.asp?id=86

Its a UK site, but the materials (or equivalents are available anywhere)

You could also have a look at partially aromatic nylons such as Grivory, by EMS:

http://www.emsgrivory.com/

Pricey but good stuff.

Cheers

Harry

 

[Jon5]

Thanks guys for the valuable information.

Vendor performed some more trials with different materials.

Here is what we tested:

1. CHEMLON (Polyamide 66) - softened and torque completely degraded

2. RYTON (40% Fiberglass PPS) - less torque degradation but connectors molded poorly, bad fit and very brittle. This is due to the heat issue described by 'Pud'. Heaters are required but there is no room in the tooling - right again 'Pud'!

3. MINLON (36% Mineral Polyamide) - poor results, acted just like the (1) CHEMLON.

4. VECTRA (30% Glass LCP) - performed similar to (2) RYTON, brittle with torque degradation. RYTON a bit better than this material.

So it sounds like I should investigate PBT, PES, or some higher end Polyamides.

 

[CoryPad]

For higher-end polyamides, try Stanyl PA46 from DSM:

http://www.dsm.com/en_US/html/dep/stanyl.htm

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Pud]

Has your supplier got dryers able to dry the materials? I cannot see why PA6.6 performed worse than PA6 - I would check processing conditions - from bag to part.

PBT will require very good drying -(less than 0.02% moisture)- a lot dryer than nylons need. Hopper and hot air dryers will be insufficient. Dessicant or vacuum drying required.


Cheers

Harry