The combination of Lean and Six Sigma allows us to measure and compare many different types of processes. Both Lean and Six Sigma focus on the customer and what is most valuable to them. Lean methods always begin with looking at the value stream from the customer's point of view and by determining what is value-added versus non-value-added.
Gain #1: Improved process efficiency
Process efficiency is a measurement that allows us to distinguish between value-added and non-value-added activities within any process. By completing a value stream map of your process, and then labeling each individual step as either value-added or non-value-added. Lead time is another important metric.
Gain #2: Reduced cycle time
Cycle time is the total time needed for one item or service to make through a system of processes to deliver to the customer. You need to ask yourself, how long is the customer willing to wait? How long is the lead time for competitors for the same product or service?
Both process efficiency (including wait times and bottlenecks) and overall process lead times are important dimensions to consider when evaluating your processes for improvement.
Gain #3 Reduce wait times between process steps
What are the best methods to reduce wait times in process steps? To reduce process waste from wait times, it will be important to identify and understand your process bottlenecks. This is accomplished through the use of value stream maps that help identify these stop points, which will be shown by points where there are inventory buildups and long sub-process cycle times.
Gain #4: Improve bottleneck points
You may not be able to eliminate all bottlenecks, but you can reduce the impact they have on process flow. For example, a laboratory may decide to reduce the wait times at an individual bottleneck step. Care must be taken with this approach as oftentimes the original bottleneck can be reduced or eliminated, but without looking at the entire value stream. As a result, the bottleneck may merely shift to a later, but new bottleneck step. This is frequently observed when organizations are overly focused on the vertical improvement, also known as "silos," without considering the downstream or horizontal value-added process. That is why the entire process with all inputs and outputs must be taken into consideration. Better results may be achieved when efforts are placed in reduction of the overall cycle time by work standardization, elimination of non-value added steps and process flow.
Gain #5: Reduction of batch processing
Efficiency is increased and errors are reduced in a continuous workflow. The problem of batch processing can be difficult to overcome. However, the batching problem is made more evident with value stream mapping and made obvious wherever you see work-in-progress piling up. The wait times introduced by the bottlenecks can be alleviated by trying to work with the smallest batch sizes possible and work towards seeking a continuous flow.
Gain #6: Limiting rework
The addition of rework adds unnecessary wait time at the most process-vulnerable points (process bottlenecks), and this is why rework and defects must be minimized. Error reduction techniques such as Poka Yoke methods, 5S work area redesign for efficiency, and standardization can help reduce the waste introduced by rework.
