What do we mean by "Pull" in Lean material management?
This video defines and provides an example of what is meant by "Pull" in the world of Lean Material Management.
Here is the definition of Pull, or what a Pull Signal means. When work or materials are being Pulled, you can’t actually move the work or material forward until there is a signal to do so, like an empty space, an empty container, or a physical card. This method eliminates the possibility of inventory accumulating between steps, beyond whatever quantity is defined as a part of the process design.
Let’s go back to our sandwich making example, and look at an example of Pull.
Here’s how sandwiches can be make with the Pull method. You set up a signal, or a limit, on the number of sandwiches that you will make ahead of time. Maybe this is a tray that only holds a certain number, and as it is emptied you refill it.
You make sandwiches, up to the limit you have set. You don’t make sandwiches for the entire day, so you’ll need to be making them during the day, as they are sold. You will need to have the ingredients on hand as well, of course.
Customers buy sandwiches, and when your small stock of sandwiches gets low, you will need to make more to restock.
Here are the results you can expect.
- You sold almost exactly the number of sandwiches you made. Not necessarily 100%, but close.
- You may end the day with a few left over, but the risk is a lot less than the PUSH method.
- The sandwiches are fresher too, but not made exactly when the customer ordered them.
Who builds sandwiches (or burgers) in this way? McDonalds and a lot of other outlets follow this model. This is what we call PULL.