Pull is More Ideal Than Push, But Less Than Flow
When you have a Pull System set up then you are building a service or product for a customer. Contrast this with a Push System where each department is executing as fast as possible whether you have a customer or not. Pull Systems are also faster than Push Systems. Pull System advantages of Push Systems:
- Pull is faster than Push,
- Pull drives a System, Push drives a department,
- Pull creates much less inventory waste or fat, and
- Pull means your effort is for a product or service a customer is paying for.
Pull System disadvantages vs. a Push System:
- Pull requires more infrastructure than Push, and
- Whereas Push creates excess inventory, Pull adds a level of extra management. It is a trade-off.
There are two Pull Situations. The first uses a Kanban card as communication. The Kanban Card contains all the information to produce the product or service. The downstream process uses the Kanban Card to request a product or service from the upstream process. A Kanban Card represents a customer. There is another way to implement a Pull System without Kanban Cards. In the earlier section on “Map Your Value Streams,” the Value Stream had an example of Pull without Kanban Cards. It simply had a buffer that held Building Permit Requests. Workers would Pull a Permit Request to work on when they were ready. You could fine-tune this system such that one worker may be the expert on house wiring and another, on swimming pools.
If you build a Pull System there will be some structure that must come with it. Some systems will require the structure of Kanban Cards and others won’t. For systems that are new to Pull, I suggest starting with places that are a more natural fit and moving on from there. The advantages of Pull are listed above and if it is something you’re interested in exploring, let me know.