Foundational elements are necessary for achieving smooth one-piece flow. Few key criteria are needed which includes
- Ensure consistent capability, the level of capability should be on a daily basis. During each day the operation must be capable of fulfilling the requirements of the customer.
- Consistent capability requires consistent application and availability of resources like people, materials, and equipment. The inconsistent availability of these resources is the primary reason that flow is unsuccessful. Methods must be put in place to ensure availability of resources (not by simply adding resources, which is added cost).
- Reliability of processes and equipment is imperative. Initially this would encompass the larger issues such as downtime, or changeover, but as the process is refined it would include lesser issues such as ease and simplicity of use.
- Operation cycle times must be balanced (equal) to the takt time. Uneven work times will create waiting time and overproduction.
- Processes must be able to consistently produce good product. If there are many quality issues, one-piece flow is impossible.
- Process times must be repeatable as well. If there is much variation, one-piece flow is impossible.
- Equipment must have very high (near 100 percent) uptime. Equipment must always be available to run. If equipment within a manufacturing cell is plagued with downtime, one-piece flow will be impossible.
- Processes must be able to be scaled to takt time, or the rate of customer demand. For example, if takt time is 10 minutes, processes should be able to scale to run at one unit every 10 minutes.
Rules to follow
- Structure every activity.
- Specify and simplify every flow path.
- Keep the flow simple and waste-free simply by letting it flow.
- The connection between consecutive operations should be so clear they can see each other.
- Clearly connect every customer and the supplier.