Hi Ryan and All,
> Theory of Constraints is now one of the courses most industrial
> engineering programs and even some manufacturing engineering programs
> require. As I have been told, it is an idea that Henry Ford started,
> later
> refined by Edward Demming, and perfected by Toyota.
>
They are certainly in the same vein but I wouldn't say Deming, Ford
or Ohno did TOC. My understanding on this subject is that Deming focused on
quality of the process not the product (the old QC vs. QA). He did this
with Shewhart's providing the statistical know how.
Ford created the assembly line with a physical buffer between
operations where everything is linear (moving at the same speed). Ohno did
a similar thing with his Kanban cards. Goldratt added buffers to give us
synchronized manufacturing. Buffers protect the flow of product moving
through the shop and make sure you hit your deadlines or even better beat
them. :-)
> The theory can get quite in-depth, but in a nutshell, it is the
> idea
> of determining your slowest step or process on the manufacturing line;
> otherwise known as the constraint. Since nothing can move through the
> constraint any faster than the constraint, it makes no sense to produce
> things at the other steps faster than the constraint. If you want to
> manufacture things faster than the constraint allows, then speed up the
> constraint.
>
> Many people really have a BIG problem with slowing down other
> processes to match the speed of the constraint. (It's at this point that
> I
> start to argue with people). No matter how fast things are built at other
> points in the process, once it gets to the constraint, the speed by which
> it
> is processed is fixed. No matter what!!!!. Building things faster at
> other
> points in the process will never make it go through the constraint any
> faster. Since by definition, it must go through the constraint.
>
> However, finding the constraint is the hard part. Most people try
> to do it with a stop watch. I don't feel that a stop watch works at all;
> mostly because I have never seen a static manufacturing line. Typically,
> manufacturing lines are dynamic, causing a constraint to move from one
> hour
> to the next. Statistically, a constraint will occur is one process more
> often than any other place. It is because manufacturing lines are dynamic
> that a constraint is not obvious, consequently, people don't see the value
> in slowing down a process for some "phantom" constraint.
>
I haven't had much trouble finding our constraints. (I only needed
statistics to prove the constraints exists to others.) Just walk around the
shop floor and watch for excess inventory. The real work is in maximizing
the constant/s once you find it/them.
Now I'm curious - how many folks are using/heard of Leading the
Journey (The Buffalo Book)?
Hans
~~~~~~~~
Hans M. Hinners
Materials (& Process!) Engineer
Warner Robins - Air Logistics Center/Avionics Production Division
Manufacturing Branch (LYPME)
380 Second Street, Suite 104 (Building 640)
Robins AFB, GA 31098-1638
912-926-1970 (Voice) 468 - 1970 (DSN) 912-926-7164 (Fax)
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