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Finite Capacity Scheduling

FCS: Features, Functions and Applications

Finite Capacity Scheduling: Features, Functions and Applications

Written by: Bill Kirchmier 5/7/2012

Material resources are discrete items and easy to allocate. The demand side of the equation; detailing when capacity resources are required, is a difficult scheduling problem and ignored by ERP systems. Capacity resource availability is a time dependent function; each capacity operation requires finite information about demand and availability of every operation of every job. However since capacity resources are assumed to be infinite and not included in routings there is no descrete information available.

ERP systems create routings to define at what point material resources are required;  little on no benefit is derived because  is required to produce products. Work orders define where resources are required for each each operation and what quantity; however, this says nothing about when capacity resources are available to process the work order.

Scheduling capacity resources requires time dependent coordination of many conditions; including when capacity resources are available by work center, by shift and time. Multiple resource constraint requirements by operations, user defined priorities and many other time dependent constraints affect scheduling. These conditions are ignored by ERP; eliminating the ability to  coordinate and synchronize material and capacity.

The degree of scheduling precision possible is a function of the scheduling system’s ability to detail the demand and availability of material and capacity resources for every operation. This effects  predictability; consider scheduling medical procedures in hospitals. if the procedure is for cataract surgery; predictability is extremely high since conflicts for resources are minimal. Cataract surgeons regularly schedule 20 to 30 procedures a day by rotating between multiple operating OR units allocated to the surgeon.

At the other end of the medical spectrum; consider a complex open heart surgery (HMLV procedure) that requires coordinating and synchronizing multiple surgeons, anesthesiologist, nurses, technicians, equipment etc. The diversity of resources required and time dependency for the two examples (cataract and open heart procedures) are extreme and time dependency is critical. The hospital scheduling is used in IPPSA seminars to demonstrate how FCS accounts for time dependent capacity resource availability to insure feasible coordination of material and capacity resources are coordinnated throughout procedures.

The same FCS software may be used to schedule complex industrial applications and medical procedures. Two examples of scheduling complex industrial applications are described in Chapter 6 of Bill Kirchmier’s new book Finite Capacity Scheduling – Optimizing a Constrained Supply Chain.