What are the differences in how bottleneck and non-bottleneck work centers are scheduled under TOC? Why are these differences desirable?
The theory of constraints scheduling involves the preparation of an exact schedule of jobs for bottleneck work centers, and sequencing the non-bottleneck work centers by a priority-sequencing rule. Any resource whose capacity is equal to or less than the required demand is referred to as a bottleneck. As a consequence the basic principle of TOC systems is that only those work centers that are bottlenecks are of critical concern in scheduling.
This is because the bottleneck work centers limit all of the production output of a plant. Further output past the constraint of the bottleneck can be attainable only by improved utilization of the bottleneck facilities, using approaches such as reduced downtime, improved productivity, and reduced changeover times. The objective of TOC scheduling is to maximize throughput. Because the bottleneck resources limit throughput all the efforts are focused on maximizing capacity utilization in these work centers. Therefore, TOC scheduling systems focus on the identification of bottleneck work centers, and the scheduling of these work centers.
2. Why should buffers be located in front of bottleneck work centers under TOC scheduling? How should the size of the buffers be determined? The buffers are located in front of bottleneck work stations because they are a safety net of product stored just in case the bottleneck station cannot get the product out in time. It helps relieve the overall stress of the process and ensures the orders go out on time. The size of the buffer should be determined by the size of the drum or the orders you are trying to fulfill. If you have a bigger order then you are going to need a bigger buffer than if you only have small orders to fill.