3e2a1b56-dafb-454d-87ad-86adea3e7b86

Supplement to
Chapter 14
Materials requirements
planning (MRP)
Introduction
Materials requirements planning (MRP) is an approach to calculating how many parts or
materials of particular types are required and what times they are required. This requires
data files which, when the MRP program is run, can be checked and updated. Figure S14.1
shows how these files relate to each other. The first inputs to materials requirements planning
are customer orders and forecast demand. MRP performs its calculations based on the
combination of these two parts of future demand. All other requirements are derived from,
and dependent on, this demand information.
Figure S14.1 Materials requirements planning (MRP) schematic
Master production schedule
The master production schedule (MPS) forms the main input to materials requirements
planning and contains a statement of the volume and timing of the end-products to be made.
It drives all the production and supply activities that eventually will come together to form
the end-products. It is the basis for the planning and utilization of labour and equipment,
and it determines the provisioning of materials and cash. The MPS should include all sources
of demand, such as spare parts, internal production promises, etc. For example, if a manufacturer
of earth excavators plans an exhibition of its products and allows a project team
to raid the stores so that it can build two pristine examples to be exhibited, this is likely to
leave the factory short of parts. MPS can also be used in service organizations. For example,
in a hospital theatre there is a master schedule that contains a statement of which operations
are planned and when. This can be used to provision materials for the operations, such as
the sterile instruments, blood and dressings. It may also govern the scheduling of staff for
operations.