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inventories and the difference in the mechanism for triggering the need to resupply them. Figure 36-7 illustrates a traditional replenishment system4 and a TOC replenishment system. In a traditional replenishment system, the size of the parts inventory is based on a min-max type of system with the reorder point to resupply based on a predetermined physical quantity remaining, often known as the reorder point. TOC sizes the buffers based on demand patterns during the time to reliably replenish (TRR). The TRR includes a fixed reorder time interval (e.g., once a day, once a week, etc.) and that time interval is the signal to resupply the parts inventory with what has been consumed.

This is a time-based replenishment system versus an inventory-based replenishment system. The batch size is variable based on the demand during the fixed reorder interval. The inventory-based system has a fixed minimum batch size (the maximum level minus the reorder point) and the time interval to trigger resupply varies. The “time”-based system handles variability much better than the “inventory”-based system because the time-based system’s replenishment time is bounded. In the inventory-based system, the time to trigger the replenishment is unpredictable and can be very long.

The time-based system will work effectively in any environment. The focus is on managing the flow of parts in time versus managing levels of material. It really comes down to what makes you pull the replenishment trigger—time or parts.

Figure 36-8 reveals the design differences that you must be aware of when integrating TOC and Lean.

FIGURE 36-8 TOCLSS design choices.

The design choice between a balanced or unbalanced line will lead to different resource behaviors and replenishment systems. Despite what some say, the designs are not “the same just different”; the design intent is different and you will get different results depending on the environment. The “balanced” design works very well in the absence of demand, process time, and product mix variation. The unbalanced line, typically thought of as the best way to go in low volume high variability environments, actually works best in all environments.

How effectively we integrate the three methodologies depends on the design choice path that is taken. If the Lean design path is taken (balanced line, work to Takt, inventory release and replenishment), then only two of the TOC Five Focusing Steps can be applied—Step 1: Identify and Step 4: Elevate. These two steps will need to be applied continuously to identify and eliminate each new constraint. During this effort, the process will not be stable or in control. If the organization wants to experience the full power of the TOC Five Focusing Steps, the other design path (unbalanced line, relay runner work ethic, and time-based release and replenishment systems) must be followed. This path provides early system stability and focused system improvement.

TOCLSS—Fully Integrated TOC, Lean, and Six Sigma

The most powerful way to integrate TOC, Lean, and Six Sigma begins with strategy. The strategy provides the roadmap to improve business results. This strategic roadmap provides the direction for the areas of the organization that can most benefit the total system by applying improvements first. The system design of the first area provides predictable and stable system performance by focusing on protecting and managing the constraint(s) of the total system. Once this is achieved, process improvement efforts can be applied in a focused way to provide even more bottom line results for the organization. Finally, the improvements must be sustained in order for the organization to achieve real bottom line results over time.

In Fig. 36-9, the SDAIS Model illustrates the deployment framework to ensure business success by driving effective focused process improvement through TOCLSS, from a stable operational platform.

FIGURE 36-9 The Velocity Approach ((C) Avraham Y. Goldratt Institute. LP 2006–2010.)

The Velocity Roadmap to continuous business success has three