Different Forms of Drum Buffer Rope Part 5

I finished my last post by stating that when you know and understand the constraint location, and you buffer the work activity, and you send the correct release signal to the front of the line to release more work, then you have in essence implemented a system of synchronized flow.  Figure 1 defines the DBR steps and integration.

Figure 1

But wait!  With a synchronized flow, and actively implementing system subordination, there is a very high probability that the performance metric of efficiency will deteriorate quickly, at least for some period of time.  It will manifest an unacceptable efficiency performance metric that is considered undesirable by most companies.  The new mantra will be to “stop the synchronization nonsense and improve the efficiency.”  Be careful what you consider to be nonsense.  In this case, the real nonsense is the efficiency metric.  When the synchronized flow is implemented, then excess capacity at nonconstraints will be quickly exposed, at least for some period of time.  Based on the efficiency metrics it will appear that everything is falling apart, and you are headed in the wrong direction.  But through time, the new system reality and thinking will expose new evidence about what is actually happening in the system.  The new reality is this:

• Throughput rates will increase.
• Lead times through the system will be reduced.
• Work-in-process inventory will go down.
• On-time delivery will improve.

Types of Constraints

Constraints can exist in one of two types.  The first type is the internal constraint— which means that the market demand for your product is higher than the capacity of the system to produce it.  Customers want much more of what you offer then what you can produce.  It’s a good situation to be in, but only up to a point.  If you can’t figure out a way to meet market demand, then your competitors will usually figure out a way to do it for you.  This situation is ideal for implementing traditional DBR to meet the demand and capture more market (Figure 2).

Figure 2

In my next post, we will complete our discussion on different types of constraints and then we'll discuss two completely different forms of Drum Buffer Rope.

Bob Sproull