Desktop Material Requirements Planning
| Date | 01 July 1984 |
| Pages | 10-12 |
| DOI | https://doi.org/10.1108/eb057368 |
| Published date | 01 July 1984 |
| Author | Melvin Lehman |
| Subject Matter | Economics,Information & knowledge management,Management science & operations |
Desktop
Material
Requirements
Planning
by Melvin Lehman
Loyola University of Chicago, Illinois, USA
While material requirements planning techniques have been
successfully implemented on minicomputers and mainframe
computers, it is of interest to explore the possibilities of do-
ing the same on a microcomputer. Micros are more and
more frequently finding themselves on the desktops of in-
dustrial managers. This article discusses the application of
MRP on a microcomputer using the very popular electronic
spreadsheet software. The illustration may be more of a
managerial exercise than a true real world application, but
illustrates the potential of this type of analysis. In fact, in
smaller business organisations, on-going practical planning
using MRP could very well be accomplished using the
following techniques.
Since the introduction of the electronic spreadsheet
microcomputer program in 1978, it has become the most
popular kind of business applications software. The initial
entry in the US was called Visicalc and proved so successful
that there are now
several
dozen of these programs available.
Some of the newer ones have combined the worksheet
con-
cept with database and graphics capabilities. Hence they
have become truly integrated productivity tools for the in-
dustrial manager. As will be demonstrated, adapting the
software for
a
particular application involves no knowledge
of computer programming but merely entails learning the
simple rules for the particular spreadsheet program.
A good illustration of the managerial potential of this spread-
sheet idea is in its application to MRP. Here, typically a
master schedule of an assembly manufacturing environment
is related to an inventory status record and a bill of material
for product structure. The result of the outputs of the MRP
are order release requirements for the assembly and its com-
ponents. An essential part of this analysis is the "what if"
approach,
where it is necessary to be able to visualise alter-
nate schedules immediately. All of these requirements are
perfectly met by the microcomputer and the spreadsheet
program capabilities.
The Spreadsheet Program
The application to be demonstrated can be implemented
with any of the worksheet programs for micros on the
market today. One of the most popular is named "1-2-3"
and was initially designed to be implemented on the Inter-
national Business Machine's Personal Computer (PC). Quite
simply, a matrix of cells in rows and columns is presented
on the computer monitor
screen.
The cells represent what,
manually, would be rows and columns on accounting
col-
umnar paper, and the computer what would be
a
pencil and
a calculator. Obviously, since the computer provides a so-
called "electronic sheet", we achieve the power and flex-
ibility that only it can offer. Since there are many more rows
and columns available than can be viewed on the monitor,
the user can move the worker sheet about on the screen.
Entries are made for labels, values and formulae. Labels are
descriptive headings, values are the numerical quantities,
and formulae modify the values. The location of any cell
is defined by a letter (single or double) for the column and
a number for the row, with the top left hand cell designated
as
"A1".
Details of the program operation are explained as
the MRP application is presented.
MRP Application
The methodology of MRP, as used by industrial managers,
requires integration of information on order
status,
manufac-
turing or procurement order lead times, time-phased
specified requirements, and material order policy into the
classical gross-to-net requirements. A simple product struc-
ture will be used in the example and is shown in Figure 1
for an assembly consisting of two kinds of sub-components.
The number of each component required for the assembly
is shown along with the order lead time.
The relationship between the product from Figure
1
and its
associated time phase requirement structure is shown in
Table I. This represents the MRP application in the spread-
sheet format. Note the identification of rows and columns
by the letters across the top and numbers down the side.
The format shows both managerial input and computer out-
put. Inputs have been labelled in capital letters and include
the current on-hand quantities, a master schedule of re-
quired assemblies, and expected receipts of assemblies and
components. The planned releases of orders are the
prin-
cipal output.
10 IMDS • JULY/AUGUST • 1984
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