Capacity requirements planning—optimal work station capacities
Titel:
Capacity requirements planning—optimal work station capacities
Auteur:
Karni, Reuven
Verschenen in:
International journal of production research
Paginering:
Jaargang 19 (1981) nr. 5 pagina's 595-611
Jaar:
1981-09-01
Inhoud:
The How of work through a work station is analysed in terms of planned input from previous stations, planned output to subsequent stations, planned work-in-process waiting for processing and the planned queue of unprocessed work delayed for processing during sonic subsequent period. The planner is assumed to have some leeway in determining the maximum throughput during each period7mdash; the planned capacity—and is thus interested in determining the optimal capacity, to be maintained at some constant value throughout the planning horizon. This paper presents a methodology for finding the optimal planned capacity of a work station, which minimizes total costs over the planning horizon. These costs are of three types: costs of establishing and maintaining the capacity level; costs of work processing; and costs of hoi ding up work in the queue owing to insufficient capacity at any period. Various constraints are considered when characterizing the operating environment of the work station: minimum and maximum permissible queue lengths, delays, work-in-process amounts, lead times, underloading and backlogging. It is shown that these restrictions may be transformed into minimum and maximum bounds on allowable capacity levels, so that the problem becomes one of constrained optimization in a single decision variable—the planned capacity. For complex cost functions or when underloading is permissible, complete enumeration of all feasible solutions provides the simplest approach. For linear or quadratic cost functions and no underloading, the shape and smoothness of the total cost curve indicates that set of feasible capacities within which the optimal capacity lies.
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