 Levinson Productivity
Systems, P.C.William A. Levinson, P.E. Principal 570-824-1986  |
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The Automotive Industry Action Group's new publication CQI‑10: Effective Problem Solving, A Guideline decribes work flow analysis (a form of value stream analysis). Work flow analysis classifies all tasks in a process as follows.
- Operation: a value-adding activity that transforms the part
- Transportation (non-value-adding)
- Inspection (value-assisting)
- Delay or temporary storage (non-value-adding)
- Storage (non-value-adding)
- Decision (value-assisting)
- A value-adding activity transforms the part. It is something for which the customer is willing to pay.
- A value-assisting activity does not add value to the part, but it is something that would soon make its absence known if it was omitted.
- Preventive maintenance, statistical process control, inline inspection, and so on are value-assisting activities.
- Non-value-adding activities will not be missed if they are removed from the process.
We recommend consolidation of the AIAG categories as follows, with five being the practical minimum necessary to expose non-value-adding activities and to force waste (muda) to become visible. Frank Gilbreth recommended four: Process, Inspect, Transport, and Delay but, as shown below, non-value-adding manipulation of the part can then masquerade as "processing."
- Transform (value-adding)
- Handle (value-assisting or non-value-adding)
- This category is extremely important, because non-value-adding or, at best, value-assisting handling is often disguised as value-adding "processing." The truth is that no value is added except when the tool is in contact with the part. Handling is necessary to bring the tool into contact with the part, but it can be reduced through lean manufacturing techniques. As an example, a unitary machine clamps (handles) the part, performs several machining (value-adding transformation) steps, and then releases (handles) the part.
- If a worker has to rotate or turn the part, this adds no
value to it. Can the job design eliminate or at least reduce the need
to manipulate the part?
- Transport (non-value-adding)
- As an example, the work cell (which puts all the
necessary equipment necessary to do a job in sequence) reduces
transportation by eliminating the need to move parts from one
department to another.
- Inspect (value-assisting)
- "Inspection" includes not only classical inspection by people, which is considered a last resort when no better method is available, but also automatic inline inspections, go/no-go gages, and similar activities that support the principle, "Don't make it, don't take it, and don't pass it on," with "it" referring to nonconforming pieces.
- Inspection encompasses "Decision," because it usually includes a decision to pass or reject the part.
- Delay (non-value-adding)
- Includes all forms of storage, waiting, and so on. As an
example, waiting to accumulate a transfer batch is non-value-adding
delay.