Colorant Percentage

[Shorty]

I have a question, I do not know anything about running molding machines but I am over inventory for a couple of our customers.
Both of them I have to keep up with their goods here, one I just count the gaylords of plastic they have here. The other is a little more in depth, I got to keep up with how much plastic and colorant lbs. they have. Not only that but keep up with how much lbs. we use per day and also I have to do QC.

OK, the part weighs average 2.55lbs. and we use 2% black color, lets say we make 1500 parts in 24 hrs. How much color did we use?

I come up with 76.5 lbs. What I do then is subtract that from the day before to get what we have on hand but when I went and looked at it today we have 1200 lbs. more than what I've been sending them on inventory. So therefore we must not be using as much as I thought, right?

Thanks,

[rickbatey]

You stated the part weights but NOT the shot weights! You have to consider the runner weight and scrap as well. But unless color matched you may not be using to 2% rate you stated. How are you adding the colorant? If using auger/volumetric feeders, you have to check the actual usages due to pellet size changes. You may not be experiencing the expected scrap or start losses resulting in a more efficient usage.
Rick.

[Shorty]

There is no runner, when the part comes off the mold there maybe just sliver of flash they trim off.
They put in a feeder but I don't know what it is set on, I told them it needed to be 2%.

This is how I figured it up - 1500 x 2.55 = 3825 x .02 = 76.5 lbs of colorant.

[rickbatey]

What are you using to add the color? That is more than likely the root cause. That's better than them using too much color! Do you use a color meter to confirm color? If so the match may be off and that's why they are using less colorant.
At a glance your math looks solid.
Rick.

[JayDub]

First off - is your part count accurate? Also - do scrap parts go in the granulator and get used as regrind?