Page 402 - Orlicky's Material Requirements Planning

CHAPTER 21 Historical Context 381

George Plossl in the second edition of this book (1994) claimed the following prob-
lems handicapping planning systems:

1. Weak elements. Overselling MRP as a “system,” not just the priority plan-
ning element, diverted attention from the implementation of master sched-
uling to drive it and capacity requirements planning to plan the resources
needed to support it.
2. Missing elements. Almost universally, capacity control was a missing link.
Believing that capacity planning was weak, companies failed to utilize
input/output control for the major benefits this made possible, even with
crude capacity planning.
3. Oversophistication. MRP program designers, obsessed with the po tential
power of computers and software, attempted to build into MRP capabili-
ties to cope with every eventuality in manufacturing and to include every
known technique, however little use these would be. Part-Period
Balancing with Look-ahead/Look-back lot sizing (see Chapter 8) is a clas-
sic example.
4. Invalid data. MRP to many users has meant “More Ridiculous Priori ties”
because of data errors. This subject is discussed in depth in Chapter 10 and
mentioned in several others.
5. Lack of integration. Data must flow from files in design engineering, process
engineering, order entry, purchasing, plant floor, and many other activities
into planning and control files and back out. Transposing these data manu-
ally between files delayed the flow, disrupted the timing, and destroyed
accuracy. Planning, however well done, was late, unresponsive, and
invalid. People could not be held accountable for executing such plans.

These problems continue to plague most planning systems today. It was long
known that the steady flow of work on assembly lines was far better for many reasons
than batch production in functional work centers with similar processing operations. In
the early 1970s, group technology (GT) was introduced to improve batch production.
This technique grouped together machines and equipment used to make families of parts
having similar physical characteristics (i.e., shape, weight, material, and dimensions) or
processing operations (i.e., machining, welding, and automatic insertion). Advan tages
included reduced processing cycle times, lower work-in-process, less material handling,
and tighter supervision. These tangible costs carried more weight in management think-
ing than the intangible benefits of faster processing, greater flexibil ity, and tighter control;
group technology was not widely applied in America or Europe.
In the early 1980s, wide interest developed in both America and Europe in Japanese
manufacturing practices because of their great advances in quality and productivity.
Japan’s increasing share of U.S. markets for autos, motorcycles, electronic equipment,
cameras, machine tools, and many other products generated great concern among U.S.