Subject:
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Re: Bulk Sales in the 21st Century
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Newsgroups:
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lugnet.lego.direct, lugnet.general
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Date:
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Tue, 11 Jul 2000 10:03:56 GMT
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Reply-To:
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SSGORE@SUPERONLINEnomorespam.COM
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Viewed:
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1004 times
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Larry Pieniazek wrote:
>
> In lugnet.lego.direct, Scott Edward Sanburn writes:
> > > In lugnet.lego.direct, Tom McDonald writes:
> > >
> > > > Color still seems to be easier to change IMO rather than a mold, as I can
> > > > imagine that process would occur faster, as the machine would not have to
> > > > pause as long (if at all) in the changeover.
> > >
> > > I disagree.
> > >
> > > Consider the example of mold tooling that was built to the same form • factor for
> > > the same machine. To change from one to the other requires merely a
> > > substitution of the tooling and a change in settings for amount of plastic • to
> > > inject, preheat, mold dwell time, cooling time, ejection rate, etc. All of
> > > which, no doubt, are just parameters to the NC control program driving the
> > > molding machine.
> >
> > That may be, but when I worked in the plastic part plant, and I changed
> > material and colors numerous times when I was a Utility, a color change
> > merely required a dumping of the material from the hopper, blowing it out
> > with a air nozzle, and a purge of the nozzle. That usually takes maybe 15,
> > 20 minutes. If you had to clean the grinder with that machine (If it was a
> > different material or color) that would take longer, and it was a real pain!
> > The mold change usually did take longer. You had to get the mold from where
> > it was, there was an area where we put all the molds, taking it to the
> > machine, with either the forklift or the crane, and then you had to line it
> > up in the machine, lower it, clamp it down on the machine, hook up the water
> > tubes for the cooling, etc. Then you need to upload the mold specs into the
> > machine computer (If it had one, we had some real old ones!), and do trials,
> > startup procedures, and quality assurance OK, and get the mold running.
> > There is also setting up for the operator, boxes, stock, if you need parts
> > for it, etc. This takes anywhere from half an hour to two hours, depending
> > on mold size, what machine it runs on, etc.
> >
> > I definately think a mold change is a bigger deal than a color change.
>
> Maybe. I dunno.
>
> I guess I would ask not how much *labor* was involved, but rather, how much
> time transpired while the machine was out of production. In your description,
> for example, the bull time to bring the new mold from storage has no impact on
> production (if properly scheduled...) the machine keeps running the old mold
> until the mold change person and the bull carrying the new mold arrive at the
> machine.
>
> There is no operator, and all the machines feed parts into the same size bins
> which then go to cassettes so that helps some too. no need to be down while
> bins are fetched, those can be prepositioned too.
>
> I suspect labor costs are a very small fraction of the rate per hour that
> having the machine down represents in lost opportunity cost.
You are just right. Actually there is a term SMED (Single Minute
Exchange of Dies) extensively used in Total Quality terminology, which
covers many methods to decrease the time consumed during die changes
down to below 10 minute barrier (single figure minute). I saw a video on
techniques used in some automotive factories (mostly Japan, of course)
for SMED and it includes many cheap things from appropriate timing and
pipelining the jobs to making needed tooling near and ready, besides
really expensive mechanisms to do that. Without doing these
improvements, it goes from 1-2 hours to half a day, and you prefer
changing colors much better to changing dies, sure.
Selçuk
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Message is in Reply To:
 | | Re: Bulk Sales in the 21st Century
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| (...) Maybe. I dunno. I guess I would ask not how much *labor* was involved, but rather, how much time transpired while the machine was out of production. In your description, for example, the bull time to bring the new mold from storage has no (...) (24 years ago, 10-Jul-00, to lugnet.lego.direct, lugnet.general)
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