Preventing errors is one of the ways Lean helps reduce waste.
Before we talk about preventing errors, let’s first talk about what errors are. They are the gap between what happened and what should have happened. Simply put they are mistakes.
Errors link to defects. Every defect that is identified can be tied to some error in an upstream process. It might be a supplier error, but it is still an error. Obviously, preventing errors in the first place prevents defects that can slip through to customers. Preventing errors reduces waste-an important foundation of Lean.
There are many ways to categorize errors:
Errors of commission: These are errors where it comes as a result of something that a person did. For example, installing the wrong option.
Errors of omission: These are errors that come from something that was not done. For example, forgetting to add an ingredient to a recipe.
Human error: This is an error attributable to a person. Keep in mind that most human errors are actually misidentified process errors. A good process goes a long way toward preventing errors. Some human error, though, is due to negligence. On occasion, people do make bad decisions and choose not to follow a process.
Process Error: This is an error that comes as a result of following the process. In effect, the process designer got it wrong.
Intermittent error: This is an error that shows up only once in a while. It can be hard to track down. It is most commonly associated with a poor process.
Lean attacks the problem of preventing errors in many ways because…
Lean pushes for standardization. When a process is non-existent or not followed, errors abound.
It reduces inventory. Excess inventory adds steps that can result in more errors-losing parts, delivering the wrong parts, damaging parts in transit, etc.
It pushes for poka yokes. These mistake proofing devices go a long way toward preventing errors.
It pushes for a continuous improvement culture. Having a team that wants to do well and improve speeds up process improvement and reduces human errors.
It promotes visual controls. Making the status of a process jump out helps prevent errors.