Pitch interval (Ip) can be thought of in two ways: 1) as a unit of time representing the (usually) smallest common pitch shared among a range of products, services, or transactions that are being produced, conveyed, performed, or executed by a given resource(s), and 2) as a count of the number of intervals of a common pitch over a period of time, typically a shift or day.
Weighted average cycle time (Tcwa), also known as “average weighted cycle time,” provides a representative average cycle time (Tc) within a mixed model environment. Varied models or services in a given cell, line or work area often have varied work contents due to different steps, duration of steps, sequence of steps, etc. Accordingly, the Tc‘s vary.
The time observation form, also known as a process study form, is a basic and often-used tool for lean practitioners. Note that here we are talking about the application of the continuous time observation method and not the work sampling method.
The form, in combination with a stop watch, serves multiple purposes, including:
Pitch is a representation of takt image - a visual and often audible management timeframe that lean practitioners use to pace and monitor value stream performance. It is typically driven by, and linked to, a value stream or line’s pacemaker process. Pitch performance is routinely tracked and reinforced with plan vs actual charts (a.k.a. production analysis boards), digital displays, lines that are “pulsed” or indexed every time interval, etc.
Machine cycle time (Tcm) represents the actual time it takes for one machine to complete all of its operations on one piece, product, patient, file, etc.
We've all encountered a "Duh" moment when we're working with time units.
Many time the problem is that we forget that there really aren't 100 seconds in a minute.
That would be the decimal trap.
For example, 4:17 as reflected on a time piece (a.k.a. stopwatch) does not equate to 4.17 minutes. If for some reason, decimals are preferred, like on the “bottom rung” of a value stream map’s lead time ladder, then 4:17 should be reflected as 4.3 minutes. Calculated as follows:
Cycle time often seems like a pretty simple concept.
Until one tries applying it in the real world.
Over the next few weeks and months, we'll explore, in detail, the math surrounding the various members of the cycle time family. Until then, the figure below may shed some light on the subject!
Benjamin Franklin said that, "Time is money."
We would be hard pressed to disagree.
Time is also a non-spatial continuum that is measured by change. But, that's another story. One that Dr. Mike, Physics Ph.D, can cover someday.
In any event, much of lean is about time and space. It's where we live and where we add value...or not.
Available Time (Ta and Tar)
Available time (Ta), sometimes referred to as available working time or net available working time, is a fundamental lean concept. It would not be unreasonable to think this math entry would be very simple. However, there are more than a few important nuances.