I could have also titled this post “I screwed up!” or “Who Screwed Up? Me!” but we try not to point the finger of blame in the Lean mindset…. it's especially uncomfortable when you have to point it in the mirror.
I was trying to make a pot of coffee, same normal routine as usual. I got back out to the kitchen to pour my first cup and I noticed something was wrong. I hadn't pushed the filter basket all the way back in to its place above the coffee pot. Coffee had spilled out and all over the counter, leaving a mess and effectively ruining the pot of coffee (although the coffee that DID get into the pot was a surprisingly drinkable rich espresso type sludge). I won't claim I created “value” there.
The coffee pot was somewhat error proofed in that the pot has a “stop and serve” feature, a physical interlock that stops the flow of coffee when the pot and basket aren't engaged properly. But, with the basket out, water still flowed from the main reservoir and mixed with coffee grounds, flowing out over the basket edge onto the counter. The error proofing wasn't 100% sufficient (nor was it designed for that process defect, I'm sure).
Now looking back to prevention… is this an error I'm likely to make again? I don't know… I've made coffee hundreds of times on that maker and, if I made that mistake before, I don't remember it. Should I put up a large sign that says “Be Careful! Don't forget to snap the basket completely into place?” I'd argue no. Signs aren't effective error proofing and the world would be very visually cluttered if we to put up a sign for every possible thing that could go wrong (although lawyers might find that to be a good idea). That's often we react to problems in the workplace — let's put up a warning sign!
I could make a “checklist” that I walk through every time I make coffee to make sure I don't miss a step. Airline pilots (thankfully) have checklists that they HAVE to go through every time, regardless of how experienced they are.
I'll skip the 5 whys analysis since you might be sick of reading about this by now. I think my final conclusion:
Error proofing should protect us from our worst days.
Most of us don't think it's going to be us who makes the mistake. But if the mistake is possible (not error proofed), then it's likely to happen to most of us or any of us.
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I would argue that errors occur because we are, after all, human and not by any means perfect. “Stuff” happens, even with sacred morning coffee!
That’s exactly WHY error proofing is so vital — we ARE human and we DO make mistakes. Saying “well, mistakes will happen” and giving up isn’t Lean thinking. Error proofing recognizes are ARE human and tries to make it harder for us to make mistakes.
A simple switch which would turn the coffe maker off if the basket is not fully engaged would then replace the need for the prevention efforts. We must remember the best prevention is that which is not required.
Yes, that simple switch WOULD be a great example of error proofing built into the device.
Doesn’t it really come down to : “Is the customer willing to pay for the error proofing feature?” Interlocks are not cheap. Mind you with mass production like in coffee makers, they might become so. I would venture to say most customers would take the chance of this not happening to them and go for the cheaper pot.
Perhaps if the basket had a red or orange stripe on it, that was only visible if the basket was not completely closed would have helped.
That would be an inexpensive solution — not complete error proofing, but would probably help.