Taiichi Ohno is often quoted as declaring: “Without a standard, there can be no improvement.” The principles of lean do not work well when everyone is allowed to choose their own work method or work sequence in which to do a job: the outcome is unpredictable; flow and pull are impossible. This reduces throughput and the carefully crafted process develops unanticipated outcomes. Without standardized work, continuous improvement activities are not manageable because any improvement will be just one more variation that is occasionally used and often ignored.
Furthermore, standardized work makes abnormalities visible. Detailed understanding of the steps needed to be taken to complete tasks is necessary to eliminate root causes of variability and permanently resolve issues. When workers use a variety of methods to complete their work, it’s not possible to develop this understanding. Therefore, standardized work provides the baseline required for continuous improvement.
Logical as this may be, the lack of standardized work is prevalent in many “lean” processes. Is it any wonder, then, why it’s impossible to sustain the gains made by your continuous-improvement efforts? Standardized work secures improvement and prevents you from backsliding. It’s the secret weapon in becoming lean.
Today, standardized work refers to a detailed, documented, and visual system by which workers develop and follow a series of predefined process steps. It should be used whenever the work requires completing a series of tasks. Production workers, administrative workers, and knowledge workers all can benefit from implementing standardized work.
The detailed process steps that we call standardized work represent the current best way for workers to proceed in the completion of their jobs. They are designed to minimize process variation introduced by the worker, and to eliminate unnecessary motion. Minimizing variation and eliminating unnecessary motion reduces waste, eases problem solving, and enhances productivity within a particular job or series of jobs in a cell.
Like everything in the Toyota Business System (TBS), standardized work is focused on what workers need to do to satisfy the customer. Unlike the routers developed by engineering, which focus on the part and how it’s processed, standardized work focuses on the workers and the steps they must take to produce the product or service. Improvement of standardized work is the responsibility of the work team. Maintenance of the standardized work documentation is the responsibility of the cell leader.
Just as the TBS is a business system, standardized work is a management system. It’s a management system for the front-line leader (cell manager), who is responsible for the performance and output of this cell.
There are five key components that every cell leader must manage effectively, and standardized work will allow the cell leader to manage them:
Staffing is the key component. Standardized work is the management system that allows you to produce to takt time with the proper level of staffing. It is important to note that cell leaders are responsible for measurable performance. It’s not enough to just get the item out the door. We must get it out the door efficiently, with good quality and minimal waste. Continuous improvement is necessary to accomplish this objective, and standardized work, as a system, will help identify areas for improvement.
The key elements of standardized work are what we see in the cell. A well-implemented standardized work system creates a very visible, very manageable environment.
We need to see a process delivering at takt time. Takt time is simply the rate of customer demand, and it’s determined by dividing the net available time by the customer demand quantity. “Takt” is the German word for the baton that an orchestra conductor uses to regulate the speed, beat, or timing at which musicians play. So takt time is “beat time,” “rate time,” or “heart beat.” Lean uses takt time as the rate at which a completed product or service needs to be finished to meet customer demand. If you have a takt time of two minutes, then every two minutes a complete product, assembly, or service must be produced.
Takt time is the single most important concept all manufacturing engineers and cell leaders must understand. If you do not fully understand the concept of takt time, take time to learn it.
Although takt time ultimately must be driven by the final customer—the one buying the product—it may, in the short term, be driven by internal forces and can vary from the final Takt takt time. We need to view the next operation as a customer, and produce to their demand. Keep in mind that this should be a temporary situation. The entire value stream should ultimately be linked to the final customer demand, and everyone should be producing at that rate. Strive to get to this point.
The cell leader needs to develop a work sequence and then see the people within the cell working to that sequence. It’s important to note that the work sequence is up to the cell leader. Just getting the job done will not cut it. The process needs to be well-thought-out and documented.
Standard WIP is what is necessary to make the cell run with flow and pull at takt time. Once we develop the standard WIP, problems will become very visible. The level of WIP should be the same when we start and when we end. Because we have standard WIP, we will be able to see variations, and know instantly if there is a problem.
There are some basic factors that must be in place before one can begin to create standardized work.
The work sequence is self-explanatory. It’s just that—the order in which an operator performs work elements within takt time. Work sequence comprises the steps each worker takes to complete the work elements associated with one item, and is not necessarily concerned with the flow of the item itself. In assigning work sequences, we need to assign one takt time of work to each worker. If every worker has one takt time of work, we are assured that we have staffed the cell properly, and that we can produce at the customer’s demand rate.
The time it takes each person to complete their work sequence is the manual cycle time. This is the time required by the worker to perform his or her manual work elements, and does not include automatic machine time.
Once we’ve determined how many workers are required to produce at takt time, we can begin to break up the work content and assign work sequences. If there is a small amount of time remaining, but not so much that we have an extra person in the cell, consider assigning that time to the downstream people. As the downstream workers finish earlier they will create a natural pull.
As discussed earlier, standard WIP is two things:
Once we’ve defined the minimum amount of standard WIP, we can see if workers are following the standardized work, and where there are problems. When we start and end each day, there should be no more and no less WIP in the cell than what we have defined as the standard WIP. If there is more or less, then we have a problem we need to address. More WIP will result in excess handling and storage (waste). Less WIP will result in people standing around waiting (also waste). The concept of standard WIP is vital because it’s a very powerful tool to help cell leaders see and solve problems. Inventory hides problems: eliminate it it, and we begin to uncover problems that we would otherwise not have been able to see and solve.
Because standardized work is a management system, the documents of standardized work are the tools of the system to help the cell leader achieve the objectives of creating the perfect process—on demand, defect free, one by one, at the lowest cost.
Six documents listed in the sidebar Documenting Standard Work detail the essential tools for managing standardized work within each cell. When developing these standardized work documents, develop a set for each typical staffing level and post them in the cell, as needed, on a standard work board.
In the process of developing standardized work and managing the cell, there are some principles that should be understood and followed.
Productivity gains will come only by redeploying people. The goal should be head-count reduction, but not in the form of a layoff. Redeploy your freedup resources to support needs elsewhere in your organization or, alternatively, assign them to full-time continuous-improvement teams. We need to be able to do more work with the same number of people or the same work with less people. That is the only way to achieve productivity improvements.
As part of improving the cell, try to find machines that can be run “hands off.” Don’t have people watching machines. Separate the manual and automated work, and separate internal and external tasks. Use “chargers” to recharge the cell with parts or supplies. These are people who allow the workers inside the cell to do the work of the cell. Have the correct number of people in the cell for today’s takt time or demand. Expect to move people around based on changing customer demand.
Standardized work is the responsibility of the cell leader and must be owned by the cell leader. No other group or individual should have the responsibility for standardized work. As the owner of the standardized work, the cell leader must think “What needs to happen if the takt time changes?” Staffing levels may need to be changed, and the standardized work documents will need to be updated. It’s the responsibility of the cell leader to develop new documentation for the changing takt times. If the cell requires more or less workers, update the standard work sheet and the combination sheets.
Standardized work is fundamental to cell performance. It’s how we get the work done efficiently and effectively. If we don’t manage to standardized work, then what are we managing to? Standardized work creates the performance we are looking for, and it will simplify the management of your work area. Find the time to make improvements, update the standardized work, and adjust for changes.
Decisions that have a direct tie to standardized work include:
These two decisions may need to be made daily, based on changing customer demand. Calculate the takt time for each day and staff accordingly.
Standardized work is a foundational element of being lean. Without it, the gains made from organizing workcells, creating flow, and deploying continuous improvement teams will only be temporary. Implementing standardized work is never easy. The detailed requirements and information have to be uncovered, revealing questions and new concerns. Time observation is time-consuming, and often an unpopular activity, particularly in technical and administrative work areas. Standardized work activities are never finished. Lean strives but never achieves perfection. With every new step towards perfection the standardized work changes. But the hard work and the constant striving to improve are worthwhile. Improved morale, quality, availability, cost and customer satisfaction is the reward.
Tim Whitmore is Vice President of Consulting Services at Simpler Consulting—North America, a business unit of Simpler Consulting, LP. He can be contacted at: firstname.lastname@example.org, or through Simpler Consulting’s website: www.Simpler.com.
This article was first published in the May 2008 edition of Manufacturing Engineering magazine.
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