Bob Hanover has a great little article about applying visual controls to household laundry on his “Thoughtput Solutions” site. (cute way to use TPS as the name for the company, too.)
The concept he outlines is the same one that is (or should be) used to trigger batch run points for kanban managed machines.
But I want to talk about machine utilization, especially of home appliances.
A modern home washing machine can cost anywhere from a few hundred dollars to over a thousand, depending on the make, model and features.
In a household like Bob’s, with two adults and seven kids, it makes sense to ensure this expensive machine is running to full capacity.
To keep the machine running, as each load is complete, the next one should be started, otherwise the machine will sit idle, and that would be bad… right?
Let’s do some math.
Typically a home washing machine completes its automatic cycle in just around half an hour.
Typically a home dryer completes its automatic cycle in around 45-50 minutes.
So, if you want avoid having the washer stand idle, what are you doing to do?
I’ll tell you what nobody does. Nobody keeps putting loads into the washer and piling up wet clothes to wait for the dryer. It is obvious that the dryer is pacing the process, and running loads through the washer faster than the dryer can take them would defy common sense. Wouldn’t it?
Yet we do this all of the time in factories.