In the world of Lean, the timing of the complex dance of syncopated work is managed through cadence.
The most visible and familiar example of cadence in Lean systems is the concept of takt time that controls the production line. The work of each station along a production line or in a work cell is executed within the same time-duration bounding-box. The concept of cadence enables load leveling, the act of shifting work from one production work station to a neighbor so that the time of execution at all work stations can be balanced to fit into the shortest, most efficient takt time. The most efficient takt time produces the most efficient total cycle time, and serves the high level goals of Lean production systems.
One of the five fundamental principles of Lean is Flow, the uninterrupted movement of value across boundaries. Cadence is the heartbeat that determines the flux of value within the system. The analogy of a heartbeat is doubly appropriate.
Like a heartbeat, the cadence of production has a systolic stage that forces flow, as work in progress moves from one station to then next. And the cadence has a diastolic stage of low flow pressure, during the execution of the tasks at each station.
The second valuable aspect of the analogy of the heartbeat is its organic nature. With increasing focus on knowledge work and management efforts to humanize the workplace in the pursuit of greater productivity, mechanical models have been increasingly displaced by organic, systemic models. And so the heart organ replaces the ticking clock or the metronome as the timing event.
In Lean Product Development also, cadence serves to both coordinate and drive the timing of events. But unlike in the manufacture and assembly of product, the cycle times of product development are much longer and the model of the beat-per-second human heart is useful, but less insightful. An example of the use of cadence in Lean Product Development is the use of Integrating Events in Set Based Concurrent Design. These events are used to put innovation ‘on a clock’ but in a way that is not counterproductive to the creative work.
The period of this development cadence extends over several weeks. For what kind of creature does this describe their heartbeat? Obviously, none, and so some other organic cadence function likely serves as a better model. The menstrual cycle leaps to mind — appropriate by period of cadence, by its somewhat variable regularity, and by its key role in the creative (innovation?) process. Of interest to me is the time variance between the two strokes of the integration event cycle, if fact of any cadenced cycle. It gets me thinking.
In a heartbeat, the two halves of the ‘lub-dub’ cycle are approximately equal in duration. In a factory setting, the division of takt time between the task of adding value and the task of movement to the next station are ideally not approximately equal in time, but rather the value-add time is maximized and the non-value-add-but-necessary time is minimized.
Allow me to detour for a quick, justification side bar here. A common caution to Lean practitioners is to avoid blindly applying the tools of Lean, but rather to use them with an understanding of the underlying principles that guide their application, the ‘why’ of the tools. Like the standards that we have developed to make our work more efficient and more effective, the principles of Lean themselves must be analyzed and sometimes challenged in the cause of continuous improvement. And so I embark on a perhaps Quixotic dive into thinking about flow and cadence.
My thinking calls into focus another fundamental principle of Lean, the pursuit of Perfection. Principle based Lean practitioners recognize Perfection, the idealized future state, as being more of a compass heading than a destination. And so the question is begged, what is Perfect Flow? Is it the reduction to zero of non-value-add but perhaps-necessary time? And if that is so, does that mean no movement (so no flow) or that value-add can be done during movement? We’ll rip this apart in our next blog. And we invite you to send your thoughts on this and all future blogs in to us to help guide our thinking and our learning.
And so as we speak of the next blog and of the value of cadence, we are announcing that we will now put a cadence to our postings, to make it easier and more predictable for those who wish to follow. We will put up some new thoughts on the first and third Tuesdays of the month, with the occasional ‘organic’ variation to our regularity. And on occasion we may throw up an intermediary blog as we get something off our mind and into words. And, again, we are interested in your feedback, so please share your thoughts with us.