Root Cause Corrective Action

Finding the root cause - and then fixing it - is a practice that should never stop in any complex system. It’s easy to see the symptoms of a problem—they manifest in defects, scrap, downtime, and lost performance. Finding the root cause is often harder, but if you don’t, you’ll be consistently chasing problems without making much progress.

#Approaches to finding the root cause

#Go and See

This can’t be emphasized enough, and if we could only give one piece of advice about manufacturing, it would be to “Go and See”. When dealing with a problem in a physical process, you need to go to the process and see what’s happening to really understand. If that’s not possible, do a video call with someone on the ground, or at the very least, take pictures and videos and load them into any issues you’re tracking in Threaded. If you only hear about a problem via email or text message, you’re unlikely to have enough context to understand what’s actually happening, and you won’t get to the root cause

#”5 Whys”

Ask “Why?” at least 5 times—not like a kid trying to drive their parents insane, but to dive deeper into a problem to understand. For example:

Q: Why are we having a spike in scrap?

A: We’ve seen an increase in paint defects.

Q: Why are we seeing defects in the paint?

A: There’s a lot of contamination in the booth.

Q: Why is there contamination in the paint booth?

A: We’re having to keep the doors open longer than before to air out, as the air exchanger isn’t working properly.

Q: Why isn’t the air exchanger working properly?

A: The filters are full and need to be replaced, but the replacement is on backorder.

The root cause? An equipment and parts issue is forcing the team to modify the process, resulting in defects. The solution? You likely need a new PM schedule for cleaning and replacing filters on the air exchanger, or you need to understand why the existing PM schedule isn’t working—has general air contamination increased?

The point is that rather than just focusing on the symptom and prescribing a corrective action—”Defects have spiked, we need to increase repair capacity to deal with scrap!”—it’s much more effective to fix the root cause so the defect doesn’t appear in the first place: “Let’s fix the PM schedule so we don’t have to keep the doors open.”

The general rule of thumb is that if you ask “Why?” 5 times, you’re likely to get to the source of the problem. It may take 3, it may take 7, but it will always take more than 1, and you should plan on asking at least 5 times.

• “Fishbone Analysis.” We’ve got more detail on this one here, but it’s a great way to organize your problem-solving to ensure you’re addressing the root cause and not missing any potential causes.

#Approaches to Corrective Action

So you’ve found the root cause - now what? Specific actions will depend on the root cause of the issue and will always vary. To be successful though, ensure the following are true:

• The corrective action is specific. “Fix yield” is not specific. “Change the filter and update the PM schedule so contaminants won’t enter the paint booth” is a good specific action.
• A specific person is assigned to complete the correction. If everyone’s responsible, then nobody is. Sometimes multiple people will work together to complete a corrective action, but one person should be responsible for its successful completion and empowered to pull in help wherever needed.
• The action has a planned due date, and that date should be urgent. If a corrective action is going to take 2 months, it likely isn’t specific enough and will drag on. Create urgency by giving an aggressive (but feasible) due date. If you can’t, reassess the corrective action to make sure it’s appropriate. There’s usually more than one way to solve a problem, and sometimes a more manual interim corrective action (ICA) that works but requires more oversight will be an important stepping stone to a more robust permanent corrective action (PCA).

You can do all of the above in Threaded by assigning actions to any affected node in a value stream. This will act as the place where the owner can update status, call for help, attach contextual files or images, and collaborate with the team to get items completed.