Drum Buffer Rope is a scheduling process developed and popularized by Dr. Eliyahu Goldratt and it is a key element of any organization that has implemented Theory of Constraints thinking. In his book, The Goal, Goldratt uses a Boy Scout team hiking a mountain to illustrate how it works. The main character is faced with a problem; how does he get his scout troop to their destination without everyone spreading too far apart?
His solution was to first identify the limiting factor in the troupe, the constraint; in this case, it was the slowest hiker, Herbie. As the constraint, Herbie set the pace or “drumbeat” for everyone else to follow. Next, a minimum distance or “buffer” was set between each hiker to ensure there was enough protection to account for any fluctuations in speed between each hiker. Finally, a rope links each hiker together, and this serves to prevent everyone from spreading out too far. The result is a team that is marching as a group in unison while still allowing for variations along the way.
In an organization, this concept allows leadership to schedule work based on the constraint’s capacity. All other processes will be subordinate to it and have a set buffer or cushion to protect against variations, ensuring a consistent flow of work. The rope is a control mechanism designed to prevent excess work being introduced into the system which would extend lead times.
The main benefits of Drum Buffer Rope consist of reducing lead times and excess Work In Process (WIP), maximizing overall system throughput, and reduction in chaos. Implementing Drum, Buffer, Rope is a simple and quick method of getting control and predictability in a system. It is crucial to do an analysis of the flow of product or information to properly identify the system constraint before implementing Drum Buffer Rope.
By: Ken Nishiguchi, Principal, Synchronous Solutions
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