Implementing Drum-Buffer-Rope in your production planning
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Put simply, Drum-Buffer-Rope (DBR) details a work schedule for the constraint (Drum), buffering the constraint so that it is never starved (Buffer), and setting a release mechanism to ensure that work gets released into the system at the right time (Rope). This systematic approach protects the weakest link in the production system against process variation and dependency, which maximizes the system’s overall effectiveness.
DBR is the production application of the theory of constraints management philosophy. The Drum is a schedule for the constraint, with the constraint being defined as the weakest link in the production line. The Buffer is the time provided for parts to reach the protected areas. (The protected areas are the Drum, the due dates and the assemblies of constraint parts with non-constraint parts.) The Rope is a schedule for releasing raw materials to the floor and is derived according to the Drum and Buffers. The Rope ensures the proper subordination of the non-constraints.
DBR takes into account Murphy's Law when developing the Buffer in that it includes a degree of protection for the unexpected. Any schedule or production plan must be productive, reliable, robust and realistic. “Productive” means it must relate to the market demand while contributing to and being measurable against the organization's goal; “reliable and robust” means that it must reflect the capability of the resources available and stand up to the inevitable disturbances or disruptions that will hit it; “realistic” means that it is capable of being done with the resources available, including material supply.
The philosophers of DBR conclude that the true constraint (the Drum) is the market. Therefore, for DBR to work effectively there must be full cooperation and communication between sales and operations. Sales cannot simply take orders and promise delivery with little or no input from operations.
To implement DBR, first identify all the processing, resource and marketing constraints within the entire system. These constraints will then factor into the planning, scheduling and controlling of all of the plant's resources. This exercise should provide a smooth and continuous flow of materials through the plant with minimal disruptions.