abiento I would be a bit nervous about reducing pressure too early with a peroxide cure especially since significant volatiles are created from the peroxide during the curing process recognizing that less volatiles are created later, but sufficient crosslinking must be established before to...
I agree you want to get out evolved gases, but you have to consider the scorch delay which is likely to be more of a factor with a part that is inches thick.
Plasticizers are low and selected for fairly high BP so should not be a factor.
The cure does not create moisture like in FKM compounds...
Graham, I agree most parts require a minimal amount of bumps.
These parts are very thick and in some cases dual duro so the process itself increase the possibility of trapped air.
Better preforming would of course be helpful so that you start out with less air, but these are very large parts as...
I've seen automated bump cycles but I always thought they were not as effective as they should have been and required too many bumps.
Should you spend more time pushing, less time on the upstroke, slower closing speed, vent design issues and/or bleed hole size, cavity pressure issues, etc. ...
Hi Does anyone know the heat transfer for HNBR with a modest amount of carbon black filler.
I assume it is similar to regular NBR also called nitrile rubber.
I believe I read it is a bit higher than natural rubber which I remember being around 0.15 in metric units.
I think NBR was about 0.24 if...
What is the heat transfer coefficent for HNBR with modest amounts of carbon black for instance.
I would presume it would be similar to regular HNBR.
Thanks
Bill
I know bumping is commonly used and with FKM incorporation of a desiccant is helpful, but how practical is it to purge a large transfer or compression mold for a peroxide cured elastomers like HNBR or EPDM and is it effective?
Thanks
gumby69
