THE PLANNER AND HIS TOOLSbyBrian Willcox CFPIM of Action MRPII | |
| Last month we looked at the inter-relationship of priorities used,
relative and absolute priority, the integrity of priorities, priority
control and vertical and horizontal dependencies. Now we need to look at
the tools available to the planner and how he uses them to make his
priorities practical and realistic - to have integrity.
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The Material Planner |
APICS defines
the "material planner" as the person normally responsible for managing the
inventory levels, schedules and availability of selected items, either
manufactured or purchased. In an MRP system, the person responsible for
reviewing and acting upon order release, action and exception messages
from the system.
In everyday terminology, it means he
is responsible for scheduling and managing “his” products through the
manufacturing process, in conjunction with the production supervision.
Where companies have advanced to scheduling their suppliers, once
purchasing have set up the agreement, the planner then works through the
supplier’s planner to organize the call-off’s or the flow of material to
match his manufacturing schedules requirement. |
Reschedule Messages |
MRP is a
priority tool and identifies on an exception basis each order due date
which is no longer in balance with the demand. We call these reschedule
messages. Each day the planner receives reschedule messages and he
needs to investigate each one in turn, and then update the system. If he
was fortunate, he was able to reschedule the delivery to that requested.
If that was not possible, either he will have closed up the operations by
reducing the inter-operation time to meet the date or reschedule the
parent assembly to a date dictated by the material
availability
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Resolving the Rescheduling Problem |
The planner
has two basic screen inquiries to assist him in resolving his rescheduling
problem. The first is the "supply and demand" schedule which shows
him the planned transactions, both supplies due in and the demands to be
issued, which should take place in the future and the dates they will
occur. In addition he has the "daily dispatch list" which indicates the work on a work center and the sequence in which it should be completed. With these two inquiries, he has up to date information available to him on each item, not only when actions are to take place, but also what they are needed for. |
| When the
reschedule message can be implemented easily the planner is fortunate, but
often in the real world the actions requested are not possible. What does
he do them? For example he receives a reschedule message to bring a
purchase order delivery date for a bracket forward by eight days. This was
caused by a cycle count stock adjustment. The supplier’s planner says the
best he can do is to bring it forward by 3 days. Now the planner needs to
see what he can do to reschedule the assembly activities by five days to
recoup the five days he will be late receiving the
component.
As this is a lower level item he might be able to reduce the inter-operation time on the welded sub-assemblies or on the final product enabling the customers order to be supplied on time. To do this he would first turn to the "supply and demand" schedule for the bracket and verify the "pegging" information. This will tell him the manufacturing order number and the parent code of the welded assembly which has created the demand for the bracket. It will also show the date it is required by. Now he would call up the copy of the routing associated with this particular works order and endeavor to reduce the total lead time by the required five days. If there were five operations on the welded assembly he might be able to reduce the queue time between each operation by one day each which would save him four days. If the company has a functional layout, one alternative might be to co-ordinate overlapping between two operations to reduce the time parts in a batch wait for the last item to be completed before the full batch is moved to the next operation. This could save most of the run time and the inter-operation time for one operation. These types of actions would result in the operations being redated for this order and they would appear high up on the daily dispatch list giving the order a high priority. Next he would have to reschedule the final product start date by one day, but again trying to save the day needed by closing up the assembly operations. Rescheduling the start day of the final product would cause reschedule messages to be created for the other parts and sub-assemblies used on the final product. This process of rescheduling upwards endeavoring to maintain the MPS or customer completion dates is called "bottom-up replanning" and is an important part of the planners job. | |
Order Compression |
Some software
packages provide a facility called "order compression" or "order crashing"
which can assist the planner in this job. You state the order start and
completion date and the system will reduce the inter-operation times
proportionally so the total lead time will fit into the time allowed. Each
operation start and completion date will be re-calculated and these new
dates will appear on the daily dispatch list. Should you have allowed
insufficient time to perform the total set-up and run times, the system
will reject the request as impractical. |
Total Role of the Planner |
MRPII is
driven by the company management, but the daily control of the schedule
falls to the planner. The planners job involves the scheduling of a group
of products and the control of the material used by those products. It is
only when you understand what the total role of the planner is and the
tools provided to assist him with the continual battle of balancing the
supply to the demand that the need to associate the purchased parts to
their assemblies becomes obvious. For our planners to be effective they
not only need these tools mentioned above, but the correct structure to
support their efforts. |
| April 1998 | |
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