The use of scheduling
Planning and scheduling requires craftsmanship. Just like the brew master,
who can smell if processes are running well, the head planner can make efficient
schedules based on his long experience. He knows the work in process and the available
capacity by heart. Previously the brew master was challenged to improve efficiency after
which process control systems have optimised most of the production processes.
Now its turn to the planner who is faced with management demands
to continuously improve the supply chain.
o retain competitive advantage, assets must be used
more efficient and the responsiveness must be increased without
giving in the high standards
for quality and safety. IT support
becomes a necessity for the
planner to achieve this goal.
Besides that the management
does not like a single point of
failure with all planning expertise
concentrated on one person.
Scheduling challenges
Let us first have a look at the
importance of planning and sched-
uling in the brewing and beverage
industry. Although customer
orders are often known months
ahead, operational planning
is still a challenge. The production
process consists of a series
of steps with specific starting times
dependent on the previous step.
The duration of a step may be
influenced by process conditions
and raw material characteristics.
Material planning needs to ensure
sufficient stock levels, taking
into account factors like shelf
life and prevention of spoilage.
Capacity planning is responsible
to provide the necessary storage
tanks and routings as well as the
packing line needed to deliver
customer orders in time. Also tightly
linked to the production are maintenance, cleaning, inspection,
and quality assurance which must
be planned.
Getting all different kinds of planning synchronised with each other
can be complex. If not properly
organised it may happen that
the output of one planning is used
as input to another and the other
way round. Then an optimum can
only be found by iteration. Often
without realising this situation
exists when planning activities
Overview BBT sequences – March 1 to 31, 2011
BBII 6/2011 ·
take place at separate departments. The only iterations take
place when typically information
on paper is exchanged during
regular meetings. Without instant
calculation or simulation this
is seldom the right setting to find
the most efficient set of schedules.
A structured
To prevent cross-linked
dependencies between schedules
usually the full process of planning
and scheduling is divided over
multiple, hierarchical layers.
Often these layers are addressed
as strategic, tactical and operational
planning. They all aim to match
demand and supply over a period
of time in order to satisfy their
goals. But the goals and the external inputs are different at each
For every lower lever in the
hierarchy the time frame is shorter
and the resulting schedule more
detailed. In general all top layers
are referred to as planning focused
on resources allocation. The lower
levels are referred to as scheduling
and considered the activity to set
a starting time for tasks and assign
resources to those tasks.
On each layer demand as well
as resource capacity are based
on forecasts and historical experience. For example the sales and
operation planning is based on
current sales forecasts, increased
consumption in summer and
a planned mayor maintenance
operation in winter. Using this
input it will divide the yearly
production into monthly targets.
Subsequently to meet these
monthly targets, in a master
schedule, production orders are
created. They take into account
the available stock levels,
expected new deliveries and
the normal production capacity.
At the level of detailed scheduling
physical quantities of material are
assigned to the orders and orders
are assigned to a specific time
slot on specific equipment.
So far a planning board can
do the job for straightforward
planning. It becomes difficult when
· BBII 6/2011
planning involves many choices
with dependencies and a variety
of consequences that cannot be
predicted. Spreadsheets designed
for this task have been extended
over the years. Even with a strict
policy, the drawback of spreadsheets is that copies will be made,
formulas get adjusted and exceptions are added. Eventually,
stuffed with formulas, some
of which likely to be obsolete,
it is doubtful if they generate
the most efficient schedule.
They certainly fail to incorporate
exceptions like production disturbances. For example a polluted
batch may cause a delay of the
concerned production order
as well as a temporary drop
in capacity. Detailed scheduling
software is able to determine
if this can be compensated
by starting a new production order
or adjusting the recipe in a next
production step.
Like car navigation software it can
determine if, taking the deviation,
you still can reach your target
in time. If not, the alternative
schedule indicates which production orders are delayed. This
is reported to the master schedule
which interprets this information
as a disturbance to be controlled
at that level.
For resource planning most input
information can be retrieved from
a limited number of administrative
systems with relational databases.
The frequency of issuing a new
plan is low enough for missing
data to be entered manually.
For a purchase order of raw
material a rough estimation
of the available stock combined
with the forecasted speed
of consumption are enough
to determine the quantity
to order. For detailed scheduling
on the other hand exact figures
are required.
The task to process a 1000 hl
batch of a specific blend can only
start if fixed amounts of specific
lots are allocated, if the routing
from the storage tanks of these
lots is available and clean, and
if the process equipment is capable
of executing the recipe. Manual
entry of this kind of data is no
Information can only be provided
by automated systems. The
complete sets of conditions that
determine if an action is allowed
to start are called business rules.
Usually this is all the plant specific
knowledge that exists mainly
in the mind of the head planner.
Within a scheduling project a large
portion of all time is spent on
translating that knowledge into
software expressions. If the right
scheduling software is selected
then implementing should be
relatively easy. It only becomes
difficult when exotic business
rules do not fit in and complicated
solutions need to be found.
Possible benefits
Suppose all process automation
is up to date, providing any kind
of information and a software
package was selected suitable
for all the business rules involved,
what possible gains are achievable? This is an important
question that determines your
business case.
The more detailed a production
schedule is, the better it is known
when resources will be needed.
Then suppliers can deliver smaller
quantities just in time, reducing
the need for stock levels and the
risk to pass its shelf life. Based
on quality analyses of received
material, either the product mix
or the process steps must
be adjusted.
Even if the change is relatively
small, instead of sticking to the
original schedule, rescheduling
may lead to a far more efficient
one. Periodic maintenance
of equipment may be incorporated
in the production schedule
by not allocating it for some time.
In the maintenance schedule
personnel and spare parts may
be allocated. An instant failure
cannot be scheduled.
However based on what-if
scenarios the planner can predict
the consequences and switch
to the best alternative schedule,
keeping costs at a minimum.
And efficient scheduling can reveal
spare production capacity which
allows attracting more volume
to produce.
Recent projects that implemented
scheduling software announced
large reductions. Either they claim
a 34 per cent shorter lead time,
50 per cent less planning effort,
or 25 per cent in safety stock.
Anyone longing to achieve
the same results should first
investigate what is feasible
in his or her specific situation.
If for example an OEE study has
revealed that better scheduling
could improve the efficiency
of the packing lines, the actual
result could appear to be that
stock moves from storage tanks
to the warehouse. Ask yourself
if this justifies your financial
investment. Will the expected
result be in line with your business
strategy and really reduce your
costs or increase customer
orders? From a critical point
of view this example shows that
scheduling should be implemented
with policy.
There is a considerable chance
that the benefits of planning and
scheduling software will be worth
the investment. But be aware that
the actual benefits depend on
a proper design to make it fit
for its purpose. This purpose
must be well defined and realistic.
Then the business rules that
determine the scheduling constraints must be specified in terms
that can be implemented into the
software. And to generate the best
possible schedule the necessary
data must be available and preferably be connected to the scheduler directly. Only then the resulting
schedule will really support
the planner and bring value
to the company.
Stefan Salger
Manager Business
Beer & Beverages
Actemium Germany,
BU Ravensburg,
[email protected],
van Vlijmen
Client Manager
Actemium Netherlands,
BU Veghel,
[email protected],