Ahne,
Ouch! my head is right!.
Once of the assumptions (and maybe not stated, but implied) of
just-in-time, and other "lean" concepts is that the demand is known, and level, or if
it is not known you have a history of demand which is then averaged into
daily demand. Where applicable, if you cannot "level" the demand, you employ
"heijunka" which is basically building set units of boards, or other
products through history of demand, knowing that if you keep building the same
amount day after day, by the end of the month, you will average out well.
Shifting the inventory to the vendor, is an older ploy which has been
around, I became first aware of it in the 80's, but it does not work to well
for the vendor does it? And as the VOLATILITY of the product increases,
(which is changes to type, quantity, and delivery times), it becomes more
difficult to sustain the supply chains efficiency. At least that is my "theory".
The Max/Min solution is similar to MRP or materials requirement planning
systems, which got a bad rep from the influx of TQM and lean concepts,
because the automation of the systems had a tendency to "push" inventory as
opposed to a "pull" or lean system. Yet many concepts of "lean" companies have
the same or similar ways to combat volatility.
This has evolved into other paradigms, of which "Agility" is one. You can
start off with a generic base or board and run much inventory up to that
point, but then as customization of boards becomes necessary with actual
orders in PCBA you only build to order. In cases whereby a board has a usage of
say 5 a year, you would not want to designate a "Max/Min" level (Imagine
holding onto several hundred types of boards with low usage). You would want
to design this board so that it can easily be modified from an existing
hi-usage board, and made to order, rather than holding onto it. Then the
technique of agility in communication comes into play in actual production,
because someone has to have the demand pop right up in their face and realize
the implications (Hey! I don't have that in stock! I have to modify
something I have!).
All the more reason why I say that supply chain efficiency starts with the
design folks involved, because a little time up front will save so many
headaches later.
Terry
In a message dated 9/17/2010 7:03:57 P.M. Eastern Daylight Time,
[log in to unmask] writes:
JOYCE: Just-in-time supply lines:
I have visited an automobile assembly plant and they were very proud that
their inventory could be counted in hours, rather than months.
But it turned out that they had shifted the burden of having enough parts
on
hand for changing assembly needs to the vendor, so he had parts on the
shelf
for the "just-in-case" situation.
But that means a financial burden for the vendor and a risk born by the
vendor. All together too much in a tough economy we find ourselves in.
TERRY: The "simple" solution for parts supply is to have a min/max
inventory
control system. If inventory drops below min you order more parts and make
sure not to exceed max.
The extremely hard part of this solution is to establish appropriate min
and
max levels, based on quantity needed, lead times, supply uncertainties,
economic realities, etc.
And together with this you need to have an approved vendor list, which gets
established with the help of the design engineers, based on parts
performance, parts reliability, vendor reliability and costs.
Ouch, my head starts spinning,
Ahne.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Joyce Koo
Sent: Friday, September 17, 2010 12:03
To: [log in to unmask]
Subject: Re: [TN] Response to Ahne
http://www.autoblog.com/2009/01/01/just-in-time-supply-lines-could-fall-vict
im-to-financial-crisis/
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