At the recent Healthcare Systems Process Improvement conference, David B. Reid, P.E. from Chick-fil-A Restaurants brought up a very interesting point about the batch size for their pressure cookers.
They don't cook one piece of chicken at a time that way. It's inherently a batch process that uses the same amount of oil and energy whether you cook one piece or X pieces.
The key is matching production to demand as closely as possible — not making customers wait and not wasting food.
Be careful about falling too hard for Lean dogma about “one-piece flow.” You can assemble sandwiches one at a time, but the pressure cooking is different.
We have to use common sense. But without making excuses for existing batch processes that are larger than they need to be.
If you're cooking a spaghetti dinner, the pot of boiling water is a similar situation. If your so-called “Lean kitchen” was cooking one piece of spaghetti at a time, you'd be using much more energy, and everybody would be ready for bed before dinner was ready.
Same thing with making popcorn and baking cookies. We even say we're making “a batch of cookies.”
Batches CAN be bad. They are sometimes necessary. At least until you can re-engineer your process to allow better flow and smaller batches.
You can also join the vigorous discussion about this topic on LinkedIn.
I interviewed David on my #Lean podcast back in 2019:
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As a spaghetti customer, I’ve never consumed it one noodle at a time. I consume one forkful at a time but I’d rather have the whole plate at once and no disruption to my eating experience. This also means I want my whole table served at once! So the spaghetti demand signal is a table size unit, not a single noodle. One piece flow is in tables.
Yeah, I think the key point is being able to keep up with demand as closely as possible. I wonder if a typical Italian restaurant batches up the cooking of spaghetti noodles or if they are cooked one serving (or a table’s worth) at a time? I’d guess they have a way to keep cooked noodles warm for a period of time to minimize waiting time for customers.
As I commented on LinkedIn… in reply to Toyota’s Keith Ingels, who wrote:
“Flow is so misunderstood. I wish we could drop the use of “one piece”! Great share!”
I wrote:
Instead of “one piece flow,” I like the phrase “small batch”… for production or Bourbon! 🤓
I think it’s great to work toward the ideal state. But to leap there immediately before the process is capable…
It’s as bad as:
1) getting rid of your finished goods inventory before you have reliable flow at the rate customer demand
2) mandating smaller run sizes on a press without first reducing changeover time
As I commented in reply to another great comment from a connection:
Our short-term technical limitations don’t have to be long-term.
I once toured the factory that produces McDonald’s fried fish patties. They turned a batch process into continuous flow by literally helping invent a continuous flow microwave oven that a conveyor belt could flow through.
The impossible became possible.
Just as smaller batches can become possible.