In continuous improvement terminology a “model line” is a closely connected series of processes that are the target of focused implementation of lean principles. It derives from the selecting a production line and converting it as the “model” for other production lines in the same factory to emulate. The same concept of the model line can apply just as well to non-manufacturing processes, as the work at Group Health Cooperative in Seattle demonstrates. The model line a popular approach to lean implementation.
Model lines are a good approach, but like any approach there are pros and cons and it is important to understand these before taking this approach to lean implementation. The following is a consideration of some of the reasons for model lines and their relative pros and cons.
Building a Model
Pro: The model line creates a model. Other lines can learn from the model line and rapidly implement by copying. The learning curve is not as steep.
Con: Model lines require that you have clear “lines.” The benefit of the model line approach is much less if you have only one line or value stream in your organization, or if you have no definable lines at all.
Contract manufacturers, extremely high mix low volume operations, or shops that do highly creative work can struggle to find develop a model line that other areas can emulate. In this case it is better to take a broad and shallow deployment approach where thorough 5S, visual management, and problem solving are put in place across the board.
Pro: The appropriate attention and resources are given to make the model line succeed. The idea of a model is to improve it in many iterations to make it as good as it can be within a short time or to demonstrate a concept.
Con: Model lines are resource-hungry in that they consumes a large portion of the resources for lean implementation within an organization. This can leave other areas neglected until the model line project is completed.
Breadth vs. Depth
Pro: A deeper implementation of lean principles and systems is possible through the model line approach. Taking a manufacturing example, a model line may be a one-piece flow production cell which integrates machining, assembly and testing, with standard work documented and practiced, a TPM and changeover reduction routine in place, and managed by the team through visual performance boards.
Con: Sometimes what an organization needs most is a broad and shallow deployment of fundamentals such a stable quality, material delivery, safety or a system of worker training.
Pro: Because lean implementation on a model line goes narrow and deep, you will identify issues in engineering, the supply chain, human resource policies, or management policy more rapidly than if a broad and shallow implementation is attempted.
Con: Lack of fundamental stability issues may not be addressed by model lines if they do not apply to the particular model line, and ignoring these issues or being unaware of them may be deadly to a lean implementation.
Pro: Because the resources are provided, problems which arise are addressed rapidly, and visible improvements are made, model lines are good ways to build support and commitment for lean implementation at many levels.
Con: Often the model line approach is used precisely because there is not commitment to change overall thinking and behavior patterns. If the motivations for the resistance to change is something other than skepticism that lean will work, showing a model line will work may still not address the root causes of resistance to change.
In conclusion, the best way to implement lean through model lines is to treat the model line as an experiment or series of experiments based on a hypothesis. The first step is always to understand the current condition, and for this the best thing to do is an overall assessment. Once this establishes the target condition of the enterprise in terms of lean, specific aims for the short-term program can be established and a model line that is good experimental material can be selected. Consider addressing foundational issues and broad and shallow stabilization issues before or in parallel to model line implementation. And remember that done properly, the value of what you learn from the model line will be far greater than the practical business benefits.