The time it takes a part to make it from the beginning of the manufacturing process to the end is called the cycle time. That time is proportional to the amount of WIP (work in process) in the system. A simple example to illustrate how WIP effects cycle time is to consider the self serve carwash. In this example the carwash is a simple station where the car drives in and sprayers and brushes automatically move back and forth cleaning the car. After 5 minutes the car drives out clean and dry. The next car in line drives in as the car is moving out.
On a busy day it is not uncommon to see a line of cars waiting. When pulling up to a carwash with 5 cars in line, you know that even though the carwash takes 5 minutes, you have to wait for all the cars in front of you get clean before you get it. In this case your cycle time is the 25 minutes for the 5 cars ahead and then the 5 minutes it takes your car to clean. So the cycle time is 30 minutes. If there was only one car in front of you then the cycle time would be 10 minutes if there were 10 it would be much longer. The same is true in a manufacturing operation, the more parts in the queue, the longer the cycle time. For manufacturing systems that have many operations, even a small amount of product at each station can add up to a large overall cycle time.
Kanban is a method that keeps the in process inventory to a low level. It effectively prevents too much material being introduced into the system. This keeps the cycle time lower and helps manufacturing be more responsive as well as the company attaining better cash flows.
Packnet is not a manufacturing systems expert; we simply build good Kanban carts that help manufacturers control their inventory.