Percent Change in MFR after molding

[tbramel]

I was wondering if there is a standard for the percent change in the MFR of a given resin after molding?

[brentb]

40% or less is what many molders look for.

KOM

brent

[Suhas]

Yes, I have also heard some numbers. However, I am not sure if there can be a 'fixed' number. It would depend on a lot of factors: types of filler, % of fillers, length of the fibers of the fillers, the end use of the part, the starting MFI value - 10% of 25 is not the same as 10% of 75 and so on.
I suggest that you actually test 'degraded' resin and come up with your own number. Another point to note is that MFI is not the true representation of molding injection speeds.
Hope this helps.
Suhas

[brentb]

Mike Sepe has some excellent articles on this subject in "Plastics Technology"
Material testing series.

KOM

brent

[Suhas]

Yes, Mike Sepe is THE BEST!
Suhas