Envelope Stuffing – demonstrating one piece flow
Mesmerize yourself with some exciting footage of people stuffing envelopes!
Actually, stuffing envelopes is a perfect lean activity for demonstrating one piece flow!
The first video shows one man taking on the task. He times himself stuffing 10 envelopes, the traditional batch and queue method. After 10 envelopes, he repeats the task, one envelop at a time. The time shows that one piece flow is faster!
Some key things to note. During the batch process, tons of inventory build up. The envelopes by their nature don’t stack very well when folded, showing some of the dangers of inventory (messy work place, bad 5S).
Now, what if your wife realized she wrote the wrong name on the wedding invitation? It would be a bit of task sorting through the stack of half opened envelopes to find the right one. The rest would be falling all over the place.
The other thing that needs to be remembered when watching these videos is the benefit of one piece flow to the downward processes. With one guy, one process, this benefit is essentially lost. But with multiple people doing the envelope stuffing in a row, you can demonstrate the real power of one piece flow. Less inventory through the process and faster cycle time for the first piece through the system.
This brings me to the second video. Here we have two teams competing against each other using two people each. This is the perfect opportunity to how one piece flow is more efficient. One person can be folding and stuffing, while the other is closing and stamping.
To do this properly, I would suggest to use 4 people in a row. Each person does one step of the process, Person one folds, person two sticks it in the envelope, person 3 seals the envelope and the last person stamps it.
With this pseudo production line, you can control the WIP in-between. Start with each person passing papers in batches of 5. Time how long it takes to go through the whole system. Nest, get each person to pass after completing one at a time. This way you can illustrate the benefits of reducing inventory between processes.