Most plants are good at firefighting. Something breaks, people jump on it, production restarts. Next month the same problem is back. The most expensive thing in manufacturing is solving the exact same problem twice.
Lean problem solving finds the root cause so the problem stays fixed. Three tools do most of the work:
- 5 whys: ask why until you reach a cause you can act on. The machine stopped. Why? A fuse blew. Why? The motor overloaded. Why? The bearing seized. Why? Nobody lubricated it. Why? That machine isn't on the lubrication schedule. Now you have something to fix, and it isn't the fuse. Five is a guide, not a rule.
- A3: a one-page problem-solving report, named after the A3 paper size. It takes one problem from background, current condition and goal through root cause, countermeasures, plan and follow-up. One page forces clear thinking, and anyone can check the reasoning.
- PDCA: plan, do, check, act. Plan the countermeasure, try it, check with data whether it worked, then act: make it the standard if it did, or go round again if it didn't. The A3 follows the same loop.
Two traps:
- Stopping at operator error: if the root cause is a person, keep asking. Why was the mistake possible in the first place?
- Weak countermeasures: if the fix is retraining, a reminder or an extra inspection, the investigation stopped early. Look for a change to the process that makes the problem hard or impossible to repeat.
Your action for today
Take one problem that has come back at least twice this year. Sit down with two people who deal with it and run a 5 whys on a whiteboard. Don't accept human error as an answer. Write down the countermeasure and the date you'll check whether it worked.
A free A3 problem solving template with a filled-in example (your 5 whys goes in the root cause box):
A3 problem solving template