In Theory of Constraints, which process is expediting driven by what is scheduled to be in the buffers to avoid idle at the constraint and missed due dates?

• A. Drum-buffer-rope
• B. Buffer
• C. Routing
• D. Expediting

Answer: (B)

Buffer management is the mechanism that uses the protected time ahead of the bottleneck to keep the system flowing. In Theory of Constraints, buffers are placed before the constraint to absorb variability and protect due dates. Expediting is triggered by the status of those buffers—specifically by what is forecast to be in the buffers. If a buffer is projected to be depleted before the required time, actions are taken to speed up material through the bottleneck so the buffer can be replenished and the constraint stays busy. This drive from the buffer’s planned content explains why expediting is governed by the buffers. The drum-rope relationship sets the overall pace and release, but the actual decision to expedite comes from buffer status rather than routing or the general expediting activity alone.