Accurately determining the appropriate stocking levels of perishable items is very important. Stock too few items and you will have disappointed customers. Stock too many and you’ll have unsold product - which has a high probability of turning into a loss.
A number of industries face this dilemma each and every day.
The WIP-to-SWIP ratio is a simple comparison of a process, line or cell’s actual work-in-process count versus its standard work-in-process inventory (SWIP). Among other things, a process’ target condition reflects the consistent execution of standardized work, including SWIP maintenance (which is why it should be a leader standard work audit point). No SWIP maintenance, no standardized work adherence. Accordingly, the target WIP-to-SWIP ratio is 1.
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.
Having trouble deciding what to do?
Some lean math can help!
Resources are not infinite. Often we have more improvement opportunities to work on than we can accommodate. A simple but powerful prioritization matrix can help us sort things out.
Blocking, not to be confused with the type that exposes one to the risk of physical injury, is a REALLY clever way to run experiments.
Blocking can be thought of as grouping experimental runs. And when experimental trials are grouped, interesting things can happen - not the least of which is you can really increase your signal to noise ratio.
Consider the following operational life data from Company ABC:
We’ve all undoubtedly had the notion of respect for people drilled into our heads. Of course, it’s easy to speak about such a principle. Much harder to live it.
In any event, let me humbly add another recipient of our deserved respect.
Process.
First, a distinction, it’s not THE Process, meaning we are not talking about one single, special process that is elevated above all others. We’re talking about ANY process within our value streams.
The process capacity sheet, also known as a table of production capacity by process or production capacity chart or process capacity table, is one of the three basic tools for establishing a standard operation. The other tools are the standard work combination sheet and standard work sheet. All three standard operations sheets are populated with data obtained through direct observation (as is the time observation form).
From my experience, there are a handful of pull system design steps. This post seeks to "simply" outline those steps and some of the math that should be considered.
However, don't let the brevity of this post mislead you. It isn't necessarily simple.
We will address more and more of the referenced math through future Lean Math posts.
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:
