The foundation of the everyday operation in Toyota Production System is Standardized Work, standardized procedures that regulate every single work step in the entire process of producing an automobile. Concentrating on human movements, Standardized Work sets up the best work sequence for each manufacturing and assembling process. Once the most efficient sequence has been determined, it is always repeated in exactly the same way, thereby avoiding unnecessary motion and wasted effort, maintaining quality, assuring safety, and preventing damage.
Standardized work establishes guidelines for three central elements of a manned work process:
- Takt Time
- Working Sequence, and
- Standard In-Process Stock
Takt Time tells the amount of time within which a given job is to be completed; the working sequence defines the step-by-step order in which each processing or assembly operation is to be performed; and standard in-process stock specifies the number of parts that should be in-process at any given time.
This information is available in the form of three standardized worksheet. By looking at these sheets, visible at each worksites, anyone can see at a glance whether or nor standardized work is being followed. Work is not considered standard unless the necessary information is put into written form on these sheets:
- Standardized Production Capacity Sheet
- Standardized Work Combination Sheet
- Standardized Work Chart
The standardized Production Capacity Sheet specifies the maximum production volume that each machine of a certain process is capable of achieving, useful information in identifying production bottlenecks.
The Standardized Work Combination Sheet shows at a glance the flow of human work steps of single work process, and for each step, useful tool for allocating manpower.
The Standardized Work Chart is a diagram indicating the work sequence for one employee and includes the other two elements that make up Toyota Standardized Work: Takt Time and Standardized Work Charts are posted at each work-site for easy reference and are important and frequently used tool for work-site management.
The most significant aspect of Work Standard is that it is established on-site, at the worksite by very people who follow the rule after they themselves set them. Each worksite manager is in charge of standardized work for his group.
It is manager 0r group leader’s job to make work assignments based on the monthly production schedule and his group’s capacity. Since production changes monthly and Standardized Work is changed to adjust accordingly, employee flexibility is a necessity. Multifunction worker development is important–every worker must know, at least, how to do the jobs directly before and after his own.
No matter how carefully work sequences are set, problems will crop up suggesting room for improvement. At Toyota, Group Leaders, with their member’s help, are free to adjust working sequence any time for improvement in quality, efficiency or safety. Thus, there is always a standardized sequence, but it is something which is fixed from the beginning and followed blindly. Standardized work is a living, flexible tool that can be changed and improved along the way.