Excerpt from the Standardization Chapter

Toyota says that the purpose of standardized work is as a "foundation for kaizen." If the work is not standardized and it is different each time there is "no basis for evaluation," meaning no reference point from which to compare. Many companies are dismayed to discover that some time after "improvements" are made the work has returned to "the old way," and that there has been no sustained improvement. Doing kaizen before standardizing would be analogous to building a house on quick sand. You may get it built, but it will be sinking fast!

You may ask, "If standardized work is the foundation for continuous improvement, why don’t we do it first?" This is a good question. Toyota points out that there are some prerequisites to developing standardized work. These prerequisites are typically dealt with during the Stability phase, and bear repeating here in case you are tempted to skip the appetizer and head to the main course. Putting standardized work ahead of Stability will surely create a condition similar to a dog chasing its tail- you will go ‘round and ‘round, but you will never get the result you desire.

Prerequisites of Standardized work A degree of stability is necessary in each of the three areas below before moving on to standardized work. Unfortunately there are not definitive measures that say, "now you are ready for standardized work." The best advice we can give is that if you feel like the dog chasing its tail, the process is not stabilized enough for standardized work.

1. The work task must be repeatable. If the work is described in "If - Then" terms it will not be possible to standardize. For example if the task is described by saying "If A happens, then do B, but if C happens, do D" and so on, it is not possible to standardize.
2. The line and equipment must be reliable, and downtime should be minimal. It is not possible to standardize if the work is constantly interrupted and the worker is sidetracked.
3. Quality issues must be minimal. The product must have minimal defects, and be consistent in its key parameters. If the worker is constantly correcting defects, or struggling with the effects of poor product uniformity (such as size variation that affects the fit of the part, and thus the time required), it is not possible to see the true picture of the work.