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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Wed, 13 Feb 2008 20:05:35 GMT
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Viewed:
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8480 times
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In lugnet.color, Tommy Armstrong wrote:
> As I have commented before- At least as long as I have been dealing with LEGO
> bricks, there have been variations in the color. But, I polish almost every
> brick I use in my little engraving business and one can see the variations more
> clearly when polished and inspecting under bright light. But overall for a toy
> brick, I have a hard time complaining. There is also color change inherrent in
> ABS plastic and some of the older blues tend to the greener side due to the
> yellowing of the plastic.
>
> Yellows for me seem to have the worst control- as some tend to the green side
> and some towards the red side. These actually clash with each other and I find
> myself constantly sorting bricks to make sure the badge for example has the same
> color.
>
> But all colors have slight variations in them. The key to living with it is just
> don't look too hard.
>
> But then again--I see colors better than most as was trained as a color matcher
> for a paint manufacturer. And trust me--color control is one hard bugger to get
> a handle one. In paint it is much more critical than in plastic blocks.
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, and now the ABS is clear/uncolored and colors are injected during
molding.
The toy business traditionally has small profit margins, and facing increasing
competition, especially from Asian countries. if ANY company wants to stay in
business, it must remain competitive, by reducing costs and doing it's best to
maintain the best quality possible.
I would be hard pressed to find anybody that could dispute the fact that storing
several tons of individually colored ABS pellets (most likely from several
manufacturers), versus storing one distinct brand of uncolored ABS would have a
significant cost savings. 1-storage costs way down. 2-economies of scale leading
to a lower price due to mass bulk purchasing of uncolored ABS 3-less suppliers
to be involved with, resulting in less time to work on company contracts, which
could lead to less manpower involved in contract negotiations. (i.e. less people
involved = less pay,and less cost to the company. All those factors decrease a
company's liability. Just about anybody will tell you the Asset to Liability
ratio is a major factor. Reduce liability, you increase the ratio, giving your
company a better indicator.
There are always factors affecting evenness of color:
-Exterior Atmospheric temperature
-Interior temperature and moisture control
-mixing equipment to ensure even distribution of dye
-regrind usage.
-QC lab lighting
If anybody has experience in plastic molding (more than me), please feel free to
add or correct. I speak from my experience molding Lexan parts used for
semiconductor plasma etching, and window latches for vinyl replacement windows.
It's not LEGO bricks, but there are a lot of general similarities that apply, as
it's generic to injection molding.
In many cases, the pellets used for plastic molding require pre-heating to
eliminate or significantly reduce moisture in the pellets and surrounding
atmosphere. (i.e. a more humid atmosphere will require longer drying times).
The introduction of moisture in a molding process can cause improper and uneven
heating of elements, and even potential cracking of a part.
There is a possibility that the way the colors are being injected into the ABS
pellets are causing an uneven mix of colors. As that part of the process, I'd
say it is virtually impossible to see how the dye is distributing in the mix.
Injecting dye into the uncolored ABS is relatively new, and I'm sure some
process guys are tinkering around with ways to improve this. (I'd wager odds
that some experiments were deemed "good enough", and were allowed to pass
through as production items).
In any injection molding process, you're going to have two major situations. one
is the "short shot". What happens when there's not enough pressure or heat to
allow the molten/plasticized ABS to fully fill the mold. The other is when
instituting a color change. during color change, you will get parts that have a
mixture of color (say.. red and yellow mixed together.). This is due to residual
color material in the injection barrel that has to work itself out.
Rather than throw the short shot and color change pieces away, it's often
economical to grind the parts up (this is known as "regrind" and can be
reintroduced into the "virgin" ABS uncolored pellets. This is not a foreign
concept in plastics manufacturing, EVERY manufacturer does this when possible
(Automotive company Saturn admits to this in some of their old advertisments).
It reduces waste as well. In some cases, limits of percentage regrind are
specified (i.e. 10% regrind, 20% regrind, etc). Obviously, the best color
choice for regrind is for darker colors, such as black, and maybe browns, as
those pigments overpower any color regrind.
If some regrind enters into lighter colors, such as yellow, white, etc, there
stands a chance the pigments in the dyes during the injection mold process may
not be strong enough to overpower some regrind material.
Another issue may be the light source used to compare and contrast colors of
bricks. Under some lighting conditions, old dark gray and bley are so similar,
it's hard to tell the difference. So, setup of the QC lab is very important
here (I'm sure Tommy can attest to that, being a color matcher).
Mold lifespan is also important. Molds only last for so long before requiring a
new mold. A company may designate their mold to be used for X hours. If trying
to stretch costs, a company may add 10% more life to the mold, if they do not
think quality will suffer without a small risk. Molds are highly expensive.
(Ask Ben Fleskes what the cost of his Big Ben Wheels molds were!)
Unfortunately, extending the life of the mold may start to cause some tolerance
issues (as evidenced my Mike Huffman's PaB observations).
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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Message has 2 Replies:
 | | Re: Variations in dark blue color.
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| It is true that where LEGO used to receive color-molded pellets for (...) Scott, a question, why is it more difficult to control the color with clear plastic than it was to control the color in the older method of using colored plastic? Is it not (...) (17 years ago, 13-Feb-08, to lugnet.color)
| | | Re: Variations in dark blue color.
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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 (...) (17 years ago, 14-Feb-08, to lugnet.color, FTX)
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Message is in Reply To:
| | Re: Variations in dark blue color.
|
| As I have commented before- At least as long as I have been dealing with LEGO bricks, there have been variations in the color. But, I polish almost every brick I use in my little engraving business and one can see the variations more clearly when (...) (17 years ago, 13-Feb-08, to lugnet.color)
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