Each step in the process should be defined and must be performed repeatedly in the same manner. Variations in the process will create quality problems requiring costly rework or scrap.
Standard Work will define the most efficient methods to produce product using available equipment, people, and material. The Standard Work depicts the key process points, operator procedures, production sequence, safety issues, and quality checks.
Finally, Standard Work must identify the amount and location of WIP inventory in the cell. Developing Standard Work is one of the more difficult Lean disciplines. Once you start to implement Flow and Pull systems your workers can get caught up in the dynamic changes and get behind in documenting those changes.