Page 398 - Orlicky's Material Requirements Planning

CHAPTER 21 Historical Context 377

operations. Their Simulated Work Input and Flow Times (SWIFT) program
showed us clearly the harmful effects of high work-in-process levels and erratic
work input rates on schedule performance and costs.
Operations researchers were intrigued by the problem of determining optimal work
sequences in complex manufacturing environments. Sophisticated and expensive com-
puter programs to plan such optimal schedules began to appear in the early 1970s; Werner
Kraus of IBM explained his program for Model 1401 computers to George Plossl over din-
ner in Stuttgart in mid-1972. As bigger, faster computers became available, IBM people in
Great Britain converted KRAUS into Capacity Loading And Sequence Scheduling
(CLASS) for the Model 1401 computers and later into Capacity Planning and Operation
Sequence Scheduling (CAPOSS) for the 360 series and later computers. Other computer
software suppliers and independent programmers in Europe and America developed sim-
ilar optimizing programs, but successful applications were the rare exception.
One of these was R. L. Lankford’s 1971 homegrown program at Otis Engineering in
Texas; this worked very well for him in predicting schedule deteriorations and altering
processing to avoid them. The problem with most such “finite loading” was not fatal
flaws in the programs but lack of support of sound planning, execution, and control.
Increasing interest in manufacturing planning and control and a growing need for
education led to the founding of the American Produc tion and Inventory Control Society
(APICS) in 1957. Chapters were quickly formed in the United States, Canada, Mexico,
Europe, and South Africa, providing a forum to disseminate information among practi-
tioners in industry, consultants, academics, and others interested. The body of knowledge
was codified, its language formalized, and examinations devel oped to test individuals’
professional competence by the APICS Certification Program Council, which George
Plossl led in the early 1970s.
In the 1990s, the Internet once again revolutionized business. Nowhere has this
impact probably been greater, at least potentially, than in the area of manufacturing logis-
tics, that is, inventory management and production planning. Until the advent of the
computer, these functions constituted a chronic, truly intractable problem for the man-
agement of virtually every plant engaged in the manufacture of discrete items passing
through multiple stages of conversion from raw material to product. The Internet
brought new business models, including customer expectations of faster response with
higher variety.
Known and available solutions to the problem in question were imperfect, only par-
tial, and generally unsatisfactory from a management point of view. The first computer
applications, around 1960, in the area of manufacturing inventory management repre-
sented the beginning of a break with tradition. The availability of computers capable of
handling information in volumes and at speeds previously scarcely imaginable consti-
tutes a lifting of the former heavy information-processing constraint and the sudden
obsolescence of many older methods and techniques devised in light of this constraint.
Traditional inventory management approaches, in the precomputer days, obviously
could not go beyond the limits imposed by the information-processing tools available at