Line balance
Our demand swings by half. Does takt time still apply?
Takt assumes steady demand and almost nobody has it. The answer is not to abandon it, and it is not to average the year. It is to pick the window you are willing to be wrong in.
Section
Lean tools
Shop floor method: what each tool is for, and the conditions it needs to work at all.
Batching
Most of your changeover happens while the machine is stopped for no reason
Time one properly and most of it turns out to be preparation that never needed the machine idle. Move that out and the batch size argument answers itself.
Flow
Moving to pull does not remove the inventory. It shows you where it was.
Push builds to a forecast and hides the surplus between steps. Pull builds to a signal and makes the same surplus visible. The second is better, and not for the reason usually given.
Standard work
You cannot automate a step that is done five different ways
Five people, one step, times from six and a half minutes to fourteen. Two of the nine minutes in the business case come out for the price of one printed page.
Batching
A batch size is a changeover time that nobody measured
Ten items, three steps, one minute each. Batched, the first one leaves in twenty one minutes. Unbatched it leaves in three, and the total work is identical.
Line balance
Takt time is a demand number, not a target
Takt tells you the beat the customer is setting. It is not a stick to beat a line with, and using it as one is the most common way its real value gets wasted.