Page 254 - Orlicky's Material Requirements Planning

CHAPTER 12 Master Production Schedule 233

an old machine shop saying calls “brute force and ignorance.” The MPS then acts as a
brain that can transmit action commands to muscle-equipped members but lacks feed-
back. It drives the organism blindly because it is insensitive to obstacles and injury. This
is, of course, extremely inefficient and costly. Today it is also unnecessary.

The Plan and Reality

The relationship between the MPS (the master plan) and the many elements of its execu-
tion is clearly visible and in precise form, thanks to the modern MRP system (the exis-
tence of standard-variety scheduling, loading, and work-assignment subsystems is
assumed). Such a system converts the master plan into a detailed plan of execution and
helps to monitor the execution proper. The linkage between plan, execution, and progress
of execution now can be maintained, and the connection can be seen at all times. This
means that it has become both desirable and feasible to close the loop, something that has
never been practical in the past. The situation in the real world of procurement and man-
ufacturing can and should be fed back to the master plan so that it may be adjusted to
better reflect reality.
In a manufacturing environment, most difficulties and problems are caused either
by obstacles encountered in carrying out procurement and manufacturing tasks or by the
MPS itself. For the overall manufacturing logistics system to function properly, the MPS
must be realistic in three ways. What can be produced (as opposed to what it would be
nice to produce) is a function of the availability of

■ Material
■ Time
■ Productive capacity

Each one of these is equally important. A lack of critical material or lead time or
capacity precludes production, and if the MPS insists on such production, it will inca-
pacitate the MRP system in its priority planning function, leading to a collapse of the
shop priority system. The manufacturing organization then reverts to form: staging,
stock-outs, assembly shortages, hot lists, expediting, confusion, and an increase in man-
ufacturing cost. The informal system takes over because the formal system, of which the
MPS is a critical part, is not doing its job.
In a manufacturing plant, probably the most commonly encountered problem is dif-
ficulty in or inability of meeting the monthly plan of shipments (shipping budget) caused
by an inability to complete final assembly owing to a shortage of components. This prob-
lem is highly visible, but it is not of primary nature. Rather, it is a symptom of a variety
of specific problems in earlier stages of the production process. These may be classified
as follows:
■ Problems in inventory planning
■ Problems in procurement
■ Problems in manufacturing