Saturday, December 07, 2013

Postscript on Cycle Time

In my last post Visual explanation of Kanban terms I included a diagram and quotation from the Lean Lexicon (Chet Marchwinski et al Eds, 4th ed., Lean Enterprise Institute, 2008) which defines the meaning of Cycle time (CT1) as:
Cycle Time (CT): How often a part or product actually is completed by a process as timed by observation.
In the interest of completeness, this postscript includes the definition of cycle time (CT2) from Factory Physics (Hopp, W.J and M. L. Spearman, 3rd ed., McGraw Hill, International Edition, 2008).
Cycle Time (CT): cycle time... is measured as the average time from when a job is released into a station or line to when it exits. (Where ambiguity is possible cycle time at station i is written CT(i).)
The definitions are clear, concise, from authoritative and up to date sources and referencing authoritative primary sources. Unfortunately they are also contradictory. It is therefore unsurprising that the relatively new Kanban community finds it difficult to agree on uniform and unambiguous terminology, since the Lean manufacturing community has already had this problem for a considerable time.
Lean Lexicon and Factory Physics - two clear, contemporary,authoritative... and unfortunately contradictory sources