Open Lines with Infinite Buffers - Principles

For open systems the throughput remains fixed and is decided by the release rate of jobs. The WIP and flow time varies according to the throughput and other system parameters. This is in contrast to a closed line, where the WIP remains fixed and the throughput and the flow time varies according to the WIP and the other system parameters.

The following principles are applicable for the open system with no buffer restriction.

• Principle (Non-Linearity in utilization):WIP and flow time increases non-linearly in utilization.

• Principle (Process Variability): For a fixed throughput level, inventory and flow time at a station are increasing in the process variability at the station.

• Principle (Arrival Variability): For a fixed throughput level, inventory and flow time at a station are increasing function of the arrival variability to the station.

• Principle (Variability Propagation): The variability of outputs from a station increases in both the arrival variability and the process variability at the station.
  

 

• Principle (Observability): Pull is more observable than push.

• Principle (Efficiency): Pull is more efficient than push.

• Principle (Robustness): Pull is more robust than push.