Bottleneck in the Work Flow vs. Constraint in the Work Process – The TameFlow Approach

One of the practices used in TameFlow Kanban is that of identifying the constraint in the work process, by looking for the work state that takes the largest average flow time. In the Kanban Method bottlenecks are typically identified by looking for queues and/or starvation. The work state in front of one that is being starved, could be a bottleneck. A work state where there are queues could also be a bottleneck. Naturally, when work state WIP limits are employed, queues are more difficult to see; but starvation is always evident.


This is a companion discussion topic for the original entry at https://tameflow.com/blog/2014-04-15/bottleneck-in-the-work-flow-vs-constraint-in-the-work-process/

The LARGEST average flow time is the “work state” with the SLOWEST flow velocity, yes? The bottleneck that does the least amount of work (per unit time), and/or takes the longest time to finish that work? As velocity is a RATE — and if the amount of work generally varies, what is the advantage of using “flow time”?
If there is more work for a particular resource to do, it could be the constraint (even if it is the fastest resource), yes?

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Rez,

Flow Time is orthogonal to the resource(s) working on an item. At ceteris paribus, Flow Time absorbs all time related variability: Wait Time, Blocked Time, Idle Time, Touch Time, Feedback Delay Time, Induced Time …

That being said, the highest average Flow Time for a given process within a Work Flow indicates where the Constraint in the Work Process lies.

Ciao

Simply that it is easier to measure, and makes it more easier to be adopted. There is a reason that we always start by measuring Flow Times - alone - without consideration for Throughput.

Naturally, that consideration - about Throughput - comes at a later stage.

Absolutely. This is how we make the distinction:

  1. Within the scope of a single team, the “steps” that the team perform are the same. That is what we try to model with a single Kanban board. The amount of work - which is represented by a Work Item on the board - is the same for all. So that distinction does not hold here. It is exactly the same situation of the boy scouts’ hike: all member have to walk the same distance. One will be the slower one: the Herbie scout. This is the Constraint in the Work Process.

  2. Within the scope of multiple teams, there Work Load will not be the same for any team. One team will be more loaded than others. It is as if you had multiple boy scout teams, all heading for the same destination, but with every team taking a different path. One of those teams will have the longest path. This is the Constraint in the Work Flow.

We explain this clearly in the “Tame your Work Flow” book.

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