In Search of the Perfect Process

In an article in 6L, a journal for Six Sigma and Lean Manufacturing professionals, Jim Womack states, "Unless you have defined from the customer's perspective what specific value is required, it is premature to begin thinking about building or improving processes to deliver it." Womack defines a perfect process as one that is:

1. Valuable
2. Capable
3. Available
4. Adequate
5. Flexible

The perfect process is valuable because it creates and adds value for customers. Start by drawing a Value-Stream Map to visualize the process. Then remove the non-value-adding steps. Don't begin by asking if a process step is valuable. First, see if the step is even needed. In other words, would the customer miss it? If the answer is "no", don't try to fix it, just eliminate it.

A capable process performs the same way with the same result every time. Improving the capability of a process is the starting place of Six Sigma. An available process can be performed every time it needs to be performed and in the standard cycle time. Availability depends on equipment reliability and uptime; therefore, it is the starting place for Total Productive Maintenance.

An adequate process has enough capacity to perform every time when it needs to be performed, without waiting. This is the concern of Theory of Constraints, Right-sized Tooling, and Lean Manufacturing System Design.

A flexible process can change over quickly from one member of a product family to another one. Perfect processes have very low setup and changeover times. These flexible processes allow small amounts of parts for different products to be made frequently, resulting in high throughput and low inventory. This is the concern of the Toyota Production System.

In addition to being valuable, capable, available, adequate, and flexible, a perfect process also has its steps linked and coordinated by:

1. Continuous flow,
2. Customer pull, and
3. Leveled production.

Continuous flow is the quickest way to get materials from point A to point B, while allowing customers to pull products out of the value stream to prevent the waste of overproduction. Leveling the volume and mix of product flow through the process permits a steady consumption of resources and minimizes the work-in-process inventories associated with batch-and-queue production.

Womack says a perfect process is waste-free. Every step is completely valuable, perfectly capable, perfectly available, exactly adequate, and highly flexible. And, every step is connected by continuous flow, noiseless pull, and maximal leveling.