Containment and Corrections vs Corrective Actions

When we encounter a problem in our manufacturing operations, we need to take immediate steps to contain the problem, by shutting down a production line or removing a batch of raw material. Or we may need to correct the issue by restarting a piece of equipment. Containment and correction limits the impact of the problem, preventing it from continuing.

But, neither containment nor correction offers a sustainable improvement. Correction does not remove the root cause nor prevents the problem from reoccurring. This is where corrective and preventive actions come into play. Corrective actions remove the root cause of a problem. And preventive actions look into the future to prevent the issue from occurring in other areas.

I find the easiest way to understand is to look at an example.

Example:

Supplier A sent raw material from three different batches. Incoming inspection performed an AQL sample of 1.5, C=0 from each batch and found the material to be acceptable. During the production run, the in-line inspectors began rejecting parts at a higher rate than normal. Upon a preliminary investigation, the rejects could be correlated to raw material from one of the three batches.

What are some immediate steps that can be taken?

Containment: Quarantine the parts produced from the suspect batch of raw material. Remove the suspect batch of raw material from all production lines.

Correction: Send the quarantined parts through 100% inspection.

At this point, the production may continue with the two good batches. However, without understanding the root of the problem, it is difficult to sustain production as we may continue to get questionable parts from the supplier. We must do a root cause investigation.

For the sake of this example, we will say that we began the investigation by measuring the failed parts and the questionable batch of raw material. We pull the drawing and measure the raw material discovering that the questionable batch of raw material was just under the required specification. We compare the drawing sent to the supplier to the specifications at our incoming inspection. We find that the drawing goes to the thousandth of an inch yet incoming inspection is measuring at a hundredth of an inch.

We need to perform a root cause analysis, perhaps using a cause-and-effect analysis tool. With that we find is that the main driver is measurement, that we are not measuring the proper specification at incoming inspection. We also find that the supplier is not adequately measuring their parts and upon further review, there is a root cause in machine in that the supplier is not current with their own tooling calibration.

So, lots of opportunity here, wouldn't you agree?

Now that we have identified root causes, we can create a CAPA plan that will eliminate the root causes. To read more about corrective and preventive action planning, click here.

For this example, here are some examples corrective actions and a preventive action.

Corrective action plan: remove the root causes to prevent reoccurrence

Action Owner Due Date

Update incoming inspection measuring criteria. JD 20220622

Open SCAR to get Supplier A current on SL 20220701

calibration of QC measuring tools.

Review supplier scorecard to consider whether RT 20220701

supplier should move to a conditional approval

until calibration rectified based on past

performance.

When considering preventive actions, there is likely opportunity to review how new raw materials are setup in incoming inspection.

Preventive action plan: address other potential root causes that could affect other production lines, activities, areas.

Action Owner Due Date

Review introduction of new products and process EA 20220701

for setting up incoming inspection to ensure

proper translation of specifications to incoming

inspection requirements when introducing new

parts.

So, to sum is all up... containment and correction are actions that address the immediate problem. Corrective actions address the root cause. Preventive actions take a broader look into the future to prevent the issue from occurring in other areas of the plant, other production lines and activities.