What’s Faster: One Piece Flow or Mass Production? Watch This Envelope Stuffing Simulation To Find Out!

We recently re-shot the first video I ever created back in 2008.

Specifically, this video shows the difference between one piece flow and mass production.

I first learned of this simulation many years ago while reading the book Lean Thinking.  In the book, James Womack writes about how he asked his children how they’d approach the stuffing of envelopes.

He wrote how his kids, like most of us, were initially drawn to mass production but later learned how one piece flow was, in fact, superior.

So, check the video out and let me know what you think.  Is it smoke and mirrors?  Perhaps I was working “faster” during the one piece flow part of the simulation?

I’d also encourage you to do the simulation yourself to see if you get the same results.

So check out the video and let us know what you think.

1. Christina Clarke

July 29, 2014 - 7:41 am

OK, so I’ve watched this several times and really struggled to understand why the second method was so much faster but it does make sense when you think about how much time is wasted by sitting the paper down and then picking it back up. The scary part is the first mass approach looks so comfortable and easy! No wonder we’re drawn to it.

• Ron Pereira

July 30, 2014 - 3:50 pm

Thanks for the comment, Christina!

2. Robert Starinsky

August 13, 2014 - 11:26 pm

Ron:

Great video/demo! I have a similar skit that I employ to demonstrate mass production and process improvement concepts. It employs 3×5 index cards and two hole punches, a handheld single punch and a two hole punch (however, you can also use a three hole punch. adjusted to print two holes, which can be used to demonstrate tooling setup/changeovers).

The audience (the class) is divided so that 1/3 of the participants work the line, 1/3 as a flow team and the rest are s the improvement team working to improve the process/flow. The event flows like a football game; the clock is stopped and each step is described or analyzed.

The idea is to punch two holes along the top margin on the card, then bundle 5 cards together (which must be numbered 1-5) using yarn loops. The cards need to be loosely assembled so they be flipped. This demo can be done as a production line or one-piece flow setting.

Inspection points can be added to measure the distance between the holes vertically and horizontally.

The process typically becomes quite engaging for the participants with many ‘aha’ moments.

Regards,

Bob

3. John Trevithick

May 26, 2015 - 3:08 pm

Thanks Ron. Fascinating how un-intuitive this is. We can study all the theory under the sun, but seeing is believing!

This reminds me of a case study you might be interested in.
A colleague of mine once consulted with a printing company that was having trouble getting its annual order of desk diaries printed on time (ie, before January 1st). By ‘trouble’, I mean they were sometimes showing up in the shops in late February – heavily marked down, of course.

Each diary consisted of 10 ‘swatches’ of pages bound together. Printing each swatch required a new setup on the (single dedicated) printing press. Each setup took time, so the company decided to print all of swatch 1 before setting up to print all of swatch 2, etc. This meant something like 10 pallets of work-in-process per swatch. Obviously, the binding of the first diary couldn’t take place until the last swatch had been printed – which took many weeks. As you can imagine, there was a lot of stock hanging around – and damage was common.

At my colleague’s advice, the company switched to only printing one pallet of each swatch at a time, instead of all 10. This met with a lot of resistance, since the printing press now did 10 times more setups and this was seen as very inefficient. But the delay in printing was more than made up for by the fact that the first batch of completed diaries could be shipped MUCH earlier. And in practice, the final delivery was shipped sooner too, because the cut-fold-bind process only had 1/10th the work to do after the final printing.

So it doesn’t even have to be ONE-piece flow to show a marked improvement. Just FEWER-piece.