Find out why. Prove the fix worked.
The rest of Nisthora tells you what happened. Root cause analysis is where your team works out why, agrees what to change, and comes back later to check it worked. It uses two tools plants already know: the fishbone diagram and the five whys.
Four steps, in order.
The tabs inside an investigation follow the method. Someone who works left to right has done a proper root cause analysis, even if nobody ever taught them one.
State the problem
What, where, when, how big. Facts only, no causes yet.
Fishbone
Spread wide: list every possible cause on six bones.
Five whys
Drill down from the likely cause until you reach something you can change.
Act, then verify
Assign actions with an owner and a date. Weeks later, check the number really moved.
Spread wide before you dig deep.
Also called an Ishikawa diagram. Six fixed bones make the team think about every kind of cause, not just the first one somebody said out loud.
| Bone | The question it asks | Examples |
|---|---|---|
| People | Who was doing the work, and what did they have to go on? | New starter, no handover, two machines on one pair of hands |
| Machine | What about the equipment itself? | Worn bearing, wrong setting, overdue service |
| Material | What went into it? | New supplier, damp batch, wrong grade |
| Method | How is the job meant to be done, and is that how it is done? | No written changeover, step skipped under pressure |
| Measurement | How do we know? Could the numbers be wrong? | Gauge out of calibration, counter miscounting |
| Environment | What was going on around the job? | Heat, damp, poor light, night shift |
Mark a cause as likely, and add the evidence for it. A cause without evidence is shown as still a suspicion.
Keep asking until you reach something you can change.
| The press stopped. Why? | Because the motor tripped |
| Why? | Because the overload relay opened |
| Why? | Because it is set to 8 amps and the motor draws 10 |
| Why? | Because it was set for the motor this one replaced |
| Why? | Because nothing in the motor swap asks anyone to check the relay |
The fifth answer is the root cause. The fix is a line on the motor-swap checklist, not a new relay. Five is a habit, not a rule: add a step only when you have an answer for it. And the answer is never a person's name; ask why it was possible to forget.
Fix it for good, and prove it.
Containment
Stops the damage today, such as sorting stock by hand. Does not fix the cause.
Corrective
Removes this cause on this machine, such as resetting the relay.
Preventive
Stops the same cause appearing elsewhere, such as checking the other presses.
One owner, one date
Every action has one person and one due date, so a late action shows as late.
Verify
Weeks later, look at the same number. If it did not move, go back to the fishbone.
Start where you notice it
Raise an investigation from a stop, an alert or a bad batch. The details are filled in for you.
One investigation per problem
If three people press Investigate on the same stop, they all join the same one.
Everyone can join in
Anyone signed in, including operators, can read and comment.
See Nisthora on your own machines.
Book a demo. We will show you live data and talk through your machines, lines and shifts.
Book a demo