Right we are up to our last topic,
scheduling and real time operations. In
this we're going to take a look at
scheduling, the planning horizon,
sequencing, flowtime, and tardiness. We're
going to talk about real-time issues and
situational awareness. So getting started
on this, let's take a look at scheduling.
To determine timing this depends on our
planning horizon the farthest point in
the future is considered in
decision-making. How far out do we want
to plan for? If we're taking at long-term
planning or are we taking a look at short
term planning? We need to decide on what
our planning horizon will be. Once we get
that long-term or short-term, we can
figure it out. Long-term planning can be
looked at make to stock, line balancing,
resource planning. Where short term is
scheduling also referred to as planning
the make to order, resource loadings,
prioritization, routing, how things will
go, and somewhere in the middle of that
is that make to assemble, aggregate
planning, material requirements planning
on when you need to order stuff. That
can't be done in the very short term,
because we need to know how long of a
lead time we have to make sure we have
everything that we need. All of these is
in there in our planning process. We look
at work center scheduling and it's
literally sequences to determine the
order in which requirements are met and
different sequences can be created with
different rules.
Simple priority sequency rules
include shortest processing time which
is known as, SPT, and the longest
processing time,
LPT. Also FCFS, first-come first-served.
So what are we looking at the shortest
processing time at how quickly can we
get things out or when do we have to
have it out by at that latest point that
we have the processing time to be able
to do this? And we might do it
piecemeal, we might do it closer to the
end look at that or for taking
especially in service areas first-come
first-served. The flow time is a length
of time a job spends in the system.
How long from beginning to end. To see
flowtime in a multiple workcentre
sequence, you can use what's called a GANTT
chart and we have an example of that
here. A Gantt chart is a scheduling
diagram that illustrates activities
across a horizontal line. So if we take a
look at weeks here. Sunday are, yes, Sunday
through Saturday we're taking a look at
what day things are. We have a start and
the task name here A,B,C,D,E,F, and G. What
are the predecessors? What needs to be
done before it? When we take a look at A,
the task name, we need to have the start
before it and that's it the same with
B. C has both A needs to be done the
first, the ID, number two needs to be
completed and here we have the duration
the number of days that it will take. So
we take a look here on our GNATT chart
at where we will start? How long it will
take?
And what that next step is going down
and we can take a look how all of these
things will progress over the weeks times or
the days times that it takes to create
each and produce each item in each
part of the item. When we take a look at
a Gantt chart and we take a look at this
we're taking a look at the number of
days the total amount of time that flow
time that it's in from points 0 to the
finish date and that's what we're taking
a look at here. We also need to know
about tardiness when we take a look at
scheduling. Tardiness is the length of
time a job is late. If a job is finished
earlier on time,
it's considered 0 for tardiness, because
it's done when we need to have it
completed. But if it's late we can
schedule it in hours and days and weeks.
It depends on what our time buckets we
are that were using here because again
these right here are written here as
days on the GNATT chart, but it's seen as
a time bucket. So it can be days, it can
be weeks, it can be hours that those are
listed out as. So is it what is a tardy?
So a tardiness of one would be at one
time bucket. So we're looking at days as
our time bucket starting this equal one
would be one day late, a tardiness is equal
of 10 would be ten days late and you
ever want to have late stuff?
No. We do want to try to get work done on
time or as close to a tardiness level
of 0
as possible. The ultimate in short term
planning horizons is real-time. This is
the present point in time or now. We
want to take a look at what the real
time is. How long does it really take?
What's happening now? Where are things
are in real time? Where they are are at
our present point in time? Not have what
they're targeting this factor will be,
not how long it takes on their the
planning horizon, but real time where are
they at now. Because success in real time
is heavily dependent on good situational
awareness. So short term planning
horizons we want to make sure we have
situational awareness.
This is a comprehension of our
environment. What's happening and its
potential for near future states. So,
sometimes you need to take a look at the
weather and find out what's happening
and if we have hurricanes coming in. That
you right now we're looking at October
in 2016 when this is being videotaped
and parts of North Carolina the roads
are flooded. People can't get in and out,
businesses can't deliver their products,
they can't produce, because their runways
are flooded. They have no way to
transport. Get things out of their plants.
This is something that needs to be taken
into consideration when we take a look
at winter weather. Snow storms that are
coming up when we take a look at
blizzards. People actually follow this
stuff to know where transportation, where
things in their supply chain will be,
getting raw materials and getting
finished ones out, having their factory
there there there people working in
factories able to get there. If you're
looking at a service side organization,
making sure that you have enough people
who are on duty, are on call to come in,
and be able to work. All of this is part
of situational awareness. What's
happening with the environment? What's
happening with political things? Where
you get your raw materials? Is there
political unrest that's building? These
are all things you need to take into
consideration when you are working with
scheduling. So this right here is the end
of our lectures. We're going to take a
look, I've got the reference sheet up
here here is what I have used. Most of
this information for this class has come
from practical operations management,
from Hersher's publishing, by Simpson and
Hancock with a good part of it also
coming from James B. Dilsworth's
operations management providing value of
goods and services third edition. That
was through Cengage learning. It is now
out of print, but the majority of the
information for this class has come from
these two items, but I have my reference
list here for you.
Thank you for taking this class. You're
up for your last exam, so let's take a
look now at that last exam.