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Señor Suhas,

I have a 3 day weekend starting today and won't get a chance to think about work. When I get back to the office I'll start working on the excel worksheets and attach them to this...

I made an excel sheet for the injection speed linearity test. Any one else has other worksheets that would like to share?

As molders, we tend to concentrate mostly on the molding process and of course the mold. But seldom times we neglect the molding machine and its reliability to give us a consistent shot to shot.
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what was the shore hardness for that TPE? I just got 2 sample bags today from Lubrizol, I actually can't wait until Monday to get them going. 70A & 80A

Hardest resin to process: Polyketone - Carilon. No part has ever been hard to mold, everything has always looked great but please don't ask me about dimensions :D

Suhas' book? Where can I get this book? (hint!). Newer presses have more bells and whistles (multiple hold profiles). The impotance is to transfer consistantly and pack/hold until the gate seals...

Gotcha! It's just when I hear eyeballed, close enough, good enough, I cringe.

If you don't have the time, money & resources there shouldn't be a need to do 4 or 5 levels. What I would recommend is a One-way ANOVA, first find out if the mean of one or more populations are...

Eye balled? Doesn't the part weight (at transfer) get documented during the qualification process?

data sheets and handbooks are a great start as rule of thumb, but this is when expertise becomes really important.

We have some elastomers here that make my head spin sometimes, even with adequate venting we still get minor shorting @EOF.

ASA is a pain too, lotsa buring...

Part weight used here.

We check and record the water flow during the mold qualification process including validation runs. Once the mold is released to production it is not being motitored unless a problem arises that the...

4 years later and still no answer: http://www.plastics.com/communities/viewtopic.php?f=6&t=26798

You could probably come up with a formula to calculate the fill time but it would just be an...

As acceptable as the customer will allow. First, the customer specification range should be identified. If cavities are inbalanced but still meets Cp, CpK requirements then you're golden.
Cp≥1.33...

Of course it would be dependant on different applications, resins, mold cavitation. But without properly setting the fill time (viscosity curve) everything else is pretty much useless.

I set those times based on the appearance of the molded part (sink) & also based on the dimension of the part.

If the process has been studied and optimized, when a problem arises, why would there be a need to "change" the process?

I mainly use 3 factors when conducting a DOE, mold, melt temp and pack pressure. The biggest driver for dimension variability has been mold temperature, followed by pack pressure.

We are starting to do DOE's on all of our molds, but prioritization is the key. 1. Quality (CpK's); 2. Scrap; 3. Performance