Re: Overlapping Operations days -- BPCS-L

Santa,

I think you need to
a) use move or queue days in FRT routings via SFC100, not work center LWK file
b) use fractions of negative overlap to reflect how soon after operation N
you want to start operation N+1
c) review whether order sizes are historically uniform ... if they are, then
the rules are easy ... if they are not, it would be another thread here what
you can do about that & what the other implications are (in our case, the
best method is based on order quantity due to high setup times, and this also
has a hit on actual cost averaging)

This is a long post in which I attempt to answer your question to best of my
ability.
I like good questions like yours that help stimulate me to become more
knowledgeable on aspects of BPCS which are important for me to know better.
Since I am on 405 CD, some aspects of this might be different for you.

We do facility specific, have volatile changes in shop requirements, driven
by volatile changes in customer requirements, and high setup bottlenecks.  We
rarely or never use routing methods, outside vendors, alternate operations.
We do use additional descriptions in lieu of notes, and we also use notes,
many basis codes, variety of crew sizes.

No one employee knows everything we are doing in all aspects of the BPCS data
base, so it is important we all know the tools of data mining & documentation
finding.

> From: srusli313@plasa.com (Santa Rusli

>
>  I am still mystified by the workings of the capacity
>  calculations involving move days and queue days to determine
>  the number of days a shop order will take.
>
>  My requirement is quite simple - producing a shop order with
>  4 steps operations to be released and finished on the same
>  day.
>
>  What should the setting be? Is this correct?
>  Operation 1: Move Days : 0, Queue Days: 0
>  Operation 2: Move Days : 0, Queue Days: 1-
>  Operation 3: Move Days : 0, Queue Days: 0
>  Operation 4: Move Days : 0, Queue Days: 1-
>
>  I am assuming that the negative one queue days will move the
>  end date to the previous day. I am sorry because I haven't
>  got BPCS at home, and the office will be closed for a week
>  due to holiday season - so I can't tried it out. Hopefully,
>  someone will shed some light. Does available capacity in the
>  workcenter also affect the number of days a shop order will
>  take?

The number of days a shop order will take is easy to answer.
It has nothing to do with capacity.
It has everything to do with rates in routings.
What capacity controls is how soon you can start work on orders, thanks to
other concurrent work that needs to be done.
Likewise MRP controls availability of raw materials & sub-components that
might be prerequisites to the shop order.

Suppose your shop order will take one day of 4 crews to complete.
That is doable if you have 4 crews simultaneously available with right skills
& not busy on other things.

Available capacity is the people & machines that can do the work.
Load is the amount of work facing them.
Overload means some work must be delayed before starting.

You use capacity info, dates due etc. to schedule do what first second, or
justify overtime or adding capacity (more machines / people) or farming out
work.

But once you start on it, assuming you have all needed components, and
factory policy is not going to drag people away from WIP, from start to
finish shop order should take same time regardless of when you start.

SSARUN07 Capacity Planning BPCS DOC which all BPCS installations should have
(some of us have better documentation) defines standard queue days as # days
an item must be at work center before production begins, but standard queue
days in work center is for reference only, not used by 406 CD.  Queue days
for shop order must be defined in item routing SFC100.  Move days not
mentioned anywhere in SSARUN07.

Just out of curiosity - are we using this reference field in our work centers?
RUNQRY *N LWK F4 record selection *YES
    WWAIT NE 0 (average queue days)
OR WSQUE NE 0 (standard queue days)
gets 0 records which I think is correct for us

SSARUN01 Shop Floor Control BPCS Documentation

FRT.RMOVE
4.1 in documentation
5.1 in Query/400
standard move time in days needed to move specified item to next operation,
for backward scheduling.  It may be negative to allow subsequent operations
to overlap or run concurrently.

We do in fact do this.  Suppose an order will take 1/2 shift to complete
operation 1.  The folks doing operation 2 can start as soon as Op 1 has done
enuf that Op 2 won't run out of the material.  Thus we could have Op 1 start
8 am, Op 2 start 8.15, Op 3 8.30, Op 4 8.45 & all Ops be completed that
afternoon.

Note when setting up concurrent operations via negative move times, and
operation with a negative move time will not have a completion date priot to
the previous operation's completion date.

The big question is how important is it for BPCS data base to accurately
reflect what you are doing ... there is a certain amount of hassle keeping
all the fields correct.  What difference does it make if BPCS does not
correctly schedule your production?  It is most important to meet promises to
customers ... if you do not have a capacity problem, it might not be
important to have your capacity load tracked accurately ... if your company
has plenty money to have inventory sitting idle, or rush delivered, it might
not be important to accurately track when you really need it.

RUNQRY *N FRT F4 record selection *YES (bottom of screen)
        RWRKC NE 0 (exclude notes)
AND RMOVE NE 0
gets zero records so we are not populating that field
perhaps we should

FRT.RQUE
4.1 in documentation
5.1 in Query/400
standard queue time in days is amount of time a job waits at work center
before setup or work performed,  This may be negative, implying that the
operation overlaps or runs concurrently with preceding operations.

My immediate reaction to this BPCS documentation is ... what is difference
between move time and queue time in how BPCS processes them, particularly in
the shared scenarios of Santa & myself with respect to overlapping operations.

Logically I'd think move time is the 2 minutes the materials take to travel
between the places where the operations get done and the 10 minutes until a
setup person gets around to picking them up, while queue time is any excess
work waiting to do next so as to keep everyone busy.

Santa ... I hope this voyage of self-enlightenment has been productive for
you.

MacWheel99@aol.com (Alister Wm Macintyre) (Al Mac)
BPCS 405 CD Manager / Programmer @ Global Wire Technologies Incorporated
http://www.globalwiretechnologies.com = new name same quality wire
engineering company: fax # 812-424-6838