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Systems for Planning and Control in Manufacturing
Table 19.3
Comparison of RCCP and CRP RCCP
CRP
Definition
Estimated load on critical resources based on MPS
Detailed evaluation of load based at workcentre level
Method
Use of MPS and product load profiles
Calculation based on all works orders
Frequency
As required
Following each MRP run – typically once a week
Objective
1 Pre-MRP evaluation of MPS 2 Operational planning
1 Post-MRP analysis 2 Determining bottlenecks
Precision
Aggregate
Detailed
Data
MPS and product load profiles
Works orders, workcentres, routings and works order status
Speed
Fast
Typically longer than MRP
Use
Virtually all users of formal manufacturing management
A minority of users
be necessary to change the MPS. As has been discussed earlier, this has serious implications for MRP planner action lists. With the increasing sophistication of RCCP systems, CRP is now used by only a minority of organizations. Nonetheless, the concepts underpinning CRP are important to understand. Moreover, the techniques underpinning CRP are a component of optimised production technology (OPT) as will be discussed in 19.10.
19.10 Optimized production technology As stated previously, many practitioners have expressed doubts over the use of MRPII. The success of Japanese manufacturers suggested a more pragmatic approach to manufacturing management. In the 1970s, an Israeli physicist, Dr E.M. Goldratt, developed an apparently new approach to manufacturing management called optimised production technology (OPT). OPT can be considered to have two parts: first, a philosophical element, which outlines a new approach to manufacturing management. Second, a finite scheduling algorithm that is more complex than MRP and is claimed to be more effective.
19.11 OPT principles OPT is derived from a simple principle: that it is the goal of a manufacturing organization to make money. In financial terms, this can be represented by three measures: