Subject:
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Re: Variations in dark blue color.
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Newsgroups:
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lugnet.color
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Date:
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Thu, 14 Feb 2008 03:01:55 GMT
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Viewed:
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8577 times
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In lugnet.color, Scott Lyttle wrote:
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In lugnet.color, Tommy Armstrong wrote:
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As I have commented before- At least as long as I have been dealing with LEGO
bricks, there have been variations in the color.
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---SNIP---
All these factors introduce some variability in the color and quality of the
part. Some are easy to control with little cost, others are not (i.e. the
80/20 rule... 80% of quality can be maintained with 20% of your budget...the
remaining 20% of quality will cost you the remaining 80% of your budget)
These are universal factors that affect every plastics company, and most
manufacturing companies as well. Outsourcing, while lowering costs, often
results in a loss of some level of control. The question is whether the cost
savings outweigh the loss of control and quality.
Scott Lyttle
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Scott:
You pretty much nailed all the points I was thinking about making here. I’ve
worked for a specialty thermoplastics compounder for 7 years now both as a
product development/formulation engineer and as a computer aided engineering
analyst. Some of the issues that you brought up here are just inherent issues
that come with molding.
One thing I would be interested to find out is whether the molders are
transferring based on time or position (Scott I’m sure you know what I’m getting
at here). I find so many our our customers that transfer based on time and then
wonder why they don’t get a consistent pack or run into shorts every 200th shot
(or something like that). Also, are they using scientific molding ala John
Bozzelli.
The other questions I have are whether TLG uses hot or cold runner systems (or
both) and what the average number of cavities is. Based on the limited gate
vestige I have to assume they are either using sub gates with a cold runner or a
full-blown hot runner system. If they are using cold runners, could some of the
short parts could be due to the “melt flipper” effect that Beaumont has
proposed?
On the color side, there are so many issues that affect color that you really
have to do a root cause analysis to determine the issue...and even then it could
be multiple issues. Some things I can think of that can affect color are:
-Base Resin Color Variation
-Colorant Dispersion/Mixing in the Molding Machine
-Molded Part Transmittance
-Shear Rate During Molding
-Mold Temperature
-Melt Temperature
-Residence Time
-Regrind Usage
-Drying of Resin (Time/Temperature & Dessicant vs. “Tray Drying”)
Finally, from what I understand, liquid color is not easy to work with and is
best suited to long production runs. It also takes some learning and tweaking
to get right. Ultimately, you need someone with a background in coloring
thermoplastics, someone who really understands molding and tooling, and someone
who understands the base resin chemistry to implement it well. That’s one
reason we choose to stay out of that arena. We only provide precolor pellets or
masterbatches mainly because those are typically easier for customers to work
with. Granted, liquid color has it’s place...I just haven’t seen it become
hugely popular.
Here’s an
interesting article in “Machine Design” called “Mastering Color”.
Just random thoughts here.
-Dave
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Message has 1 Reply:
 | | Re: Variations in dark blue color.
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| SNIP Granted, liquid color has it's place...I just (...) Very interesting article. I think the molded plastics business is in the same state of affairs that the paint industry was in the 50's and 60's in that they now need to respond quickly to the (...) (16 years ago, 21-Feb-08, to lugnet.color, FTX)
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Message is in Reply To:
| | Re: Variations in dark blue color.
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| (...) I'll echo Tommy's comments on colors. I've got four years experience working with injection molding machines, and about 8 years experience in manufacturing processes. It is true that where LEGO used to receive color-molded pellets for molding, (...) (16 years ago, 13-Feb-08, to lugnet.color)
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