A couple weeks ago, I worked with an assembler on one-piece flow of an item she was assembling. She was batching five at a time. When we started, she told me she had the best system and that there was no way my system was better. By the time we finished, she had changed her mind. Her production increased from 120 assemblies per day to 150 assemblies per day, a 20% increase.

The assembler said, “This [one piece flow] way is much easier for me. I can concentrate on one assembly, and I don’t have to worry about missing a step.”

When I was young, I helped my mother stuff envelopes at her office.  I had to fold each paper into thirds and then insert one folded paper into an envelope, seal it and she addressed and stamped them later (I’m sure it was to keep me busy after school, yet I felt important).  Being young, I took a stack and tried to fold them all at once and quickly found out that it didn’t work very well, so I had to refold each paper. Then I stuffed each envelope and then I licked each and every one.

I’m not sure how many people can relate to that story. With digital marketing, who stuffs envelopes anymore?

It wasn’t until I started learning about Lean principles that I heard about one-piece flow. I thought about those days when I was younger and the envelopes I stuffed for my mom. Could it be that I could have been faster? As a young child with a touch of undiagnosed ADHD, probably not. But I had to find out.

One-piece flow is faster than batching.  Think about how many times a person has to handle the same object. In the example of stuffing envelopes, the assembler has to handle each piece of paper at least three times and each envelope twice. Once to fold the papers, once to put the paper into the envelope, and then both are handled when the envelope is sealed. If each one is labeled and stamped separately, that is two more times.

During one-piece flow, each piece of paper and each envelope is handled just once. Pick up the paper, fold it, put it into an envelope and seal it. If you have labels and a stamp at the ready, do it then too. But please, use a sponge to seal the envelopes. After all, George Castanza’s fiancé died from licking envelopes.

If you send out a holiday newsletter, try this experiment. Split the task. Have one person do batch assembly and the other do one-piece flow and time it to see the time difference.

If you have any stories about one-piece flow, I’d love to hear about it in the comments.