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08/09/2012 06:23 PM
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What is the difference between drum -buffer-rope concept of TOC and KANBAN. I do believe basic mechanism is same except visual signaling in KANBAN. Both are consumption based replenishment.
I appreciate experts' comments on this
VN
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08/10/2012 10:25 AM
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Vikas,
I would give my opinion here although I am not an expert in either Lean or TOC. Both kanban and drum-buffer-rope (DBR) method of TOC are production control mechanisms developed before computers and data collection systems came to shop floor. DBR is based on a fundamental assumption that production system has a single constraint and all other resources have sufficiently large capacity so that the constraint determines the workflow. Drum is the production schedule on the constraint (based on demand) and rope refers to material release to shop floor based drum and allowed buffer time before the constraint. Unlike Kanban, DBR will not directly control inventory level at every stage of production. Instead, it controls the total time the material takes to reach the constraint so that the constraint is not kept waiting for material. The rope indirectly controls the total inventory at all stages before and at the constraint. DBR is based on the aggregate variation at stages before the constraint while kanban addresses variation in each process separately. Kanban does not need the assumption of single constraint.
From statistical point of view, DBR should be more efficient than kanban wherever both are applicable. In this context, one may like to compare another control mechanism, CONWIP with both DBR and kanban. CONWIP aims to maintain a constant level of WIP in the system.
Prasad
Optisol
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08/13/2012 09:38 AM
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No claim of expertise here either, but I think a major drawback of TOC is the lack of a jidoka comparable quality system. In a DBR flow any problems that arise in auxiliary processes are hidden by the buffer inventory at the bottleneck.
On a related topic, think that TOC is a great stepping stone to lean. In school my professor used Goldratt's The Goal to introduce the concept of pull, and then proceeded to build our understanding of lean off of that foundation. In retrospect, it was a great way to introduce a manufacturing concept to a bunch of 19-year-olds who've never set-foot in a factory.
Aaron
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08/27/2012 01:21 PM
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Is DBR is follows a PULL principle of LEAN?
VN
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