Buffering WIP
Buffering is “waste” - Buffering of WIP prompts double handling, requires space, prompts difficulties to respect the sequence, etc., and hence it has to be avoided.
However, the real-life sometimes does not respect nicely crafted plans, and the process owner could be confronted with:
Supposed the issues above are not of temporary nature, and there is no possibility to smoothen the workload sustainably, the process owner has now two options:
- stick to the "pure doctrine" of flow and limit input in accordance with the process-capacity at the time of the demand and accept idle capacities at times of no-demand.
- look for a sensible solution on how to buffer WIP in the process.
- Buffering must be a conscious decision and must not happen accidentally.
- It has to be defined how much WIP shall be buffered, and the necessary space to buffer the WIP needs to be identified. It needs to be defined which part of the workload shall be buffered – a "fast-track" for urgent orders has to stay open.
- Make sure that the sequence of the WIP is respected (FIFO)
- Record what is in the buffer and the utilization of buffer over time.
- Depending on the type of buffering some of the measures above might be out of proportion – still, it has to be a conscious decision, taken by management, how the buffer shall be managed.
- input peaks that are greater than the capacity of the process
- process steps are temporary out-of-sync (e.g., change of workload)
- disruptions that are outside the control of the process owner
- the next process cannot take over the output once it has been produced