Shop Order Days Mystery -- BPCS-L

Greetings BPCS Manufacturing/SFC Gurus,

Its Monday morning and you undoubtedly need something to jump start your
week.  This is my first submission to the list and I am a Business Analyst,
not a RPG programmer, so write slowly!  We are running BPCS 4.0 release 5
and are pretty much vanilla, other than some Y2K mods (problem predates
these mods), in this area.

We have long been puzzled about exactly how BPCS calculates shop order
operation start and end dates when backward or forward scheduling a shop
order through SFC500.  For the most part the dates seem to work out as
expected, but there seem to be extra days "thrown in" under some, as yet
undetermined circumstances.  For example we have an operation with 4.0 queue
days, no move days defined in the standard routing but we end up with 5 days
between the operations start and end dates (inclusive) when the shop order
is released.  We are very suspicious of the calculations in the main
scheduling engine (SFC739) and are pretty sure it has something to do with
its capacity calculations.

We have stepped through the scheduling engine (SFC739) - arduous task - and
are very confused about something.  It would seem that as the program loops
from one operation to the next, regardless of work center correlation, the
hours of capacity remaining from the previous operation's work center serves
as the basis for the next operation's hours remaining of capacity.  Maybe I
am completely missing something, but to my simple mind this makes no sense
at all.  The previous operation's work center capacity remaining is
irrelevant to the next work center's capacity.  Can anyone shed some light
on this for me?  Each of our work centers has a variable amount of standard
capacity and these remainder hour quantities leave us with partial days
which are apparently rounded up to whole days.  I think that is why we end
up with 5 days of operation queue.

At the big picture level, we really don't want a work center's capacity to
impact the start and end dates of any operations on a shop order.  Whether
forward or backward scheduling, we want the days between operations to
consistently be the sum of the queue and move days defined in the routing.
We want to see we are overloaded on the capacity reports etc, but do not
want the operation start and end dates to be affected.

If any of this makes sense to you (miraculously!) and you have some
knowledge, thoughts, or ideas related to it please get in contact with me -
steveb@dayspring.com.  I am not sure if this is better discussed off-line or
on-line so I will leave it up to those more experienced with the etiquette
of the list to make that determination.

Thanks in advance,
Stephen J. Bos, CIRM
Operations Systems Manager
DaySpring Greeting Cards
steveb@dayspring.com
501.549.6562 Phone
501.524.8813 Fax

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