Batches

Batches are groups of products that go through a process together. Batches work against the Lean principle of flow, because the first parts that are produced have to wait until the rest of the parts are completed before they can all move to the downstream process.

Batches tend to drive up inventory. It is rare that the batches meet the exact needs of the downstream process, so the completed work sits until it is used.

Batches happen for a variety of reasons. Long setup times, large distances between processes, and operating with a push system all contribute to the problem. Batches are overproduction (the worst form of waste), because more product is made than the downstream process can immediately use.

Batches have a local efficiency advantage, as it is often easier to make 10 of something than to just do one. The problem is that the waste it creates throughout the whole value stream is far greater than the small efficiency advantage.