NCDR and CAPA in Plain Words: What They Are and How to Use Them

What are NCDR and CAPA?

An NCDR is a report that records a bad lot and decides what happens to every bad piece. A CAPA is the follow-up that finds the cause and removes it, so the problem does not return. The NCDR protects today's delivery. The CAPA protects next month's.

Every machine shop makes some bad pieces. That is not the problem. The problem is what happens next.

In many plants someone re-works the pieces and everyone moves on. A month later the same pieces are bad again. The file is full of forms that say "operator careless, operator warned." And when the owner asks how many bad pieces were made last month, nobody knows.

Fixing the piece is not the same as fixing the problem.

What is a nonconformity?

A nonconformity (NC) means a requirement was not met. That is all. The requirement can come from the drawing, the customer's order, a standard, or your own procedure.

Suppose a drawing allows a diameter between 44.98 and 45.02 mm, and the inspector measures 45.04. That is an NC, even if the part will be ground later.

An NC is not only about products. It can also be in a process, a document or a system. A missing figure on a setup sheet is a system NC. It is quiet, but it is often the cause of the product NC that follows.

Treat each NC as information. It tells you that something in your process, your checking or your system allowed a bad piece to be made.

What does the NCDR do?

When Quality finds a product that does not meet the drawing, the NCDR records:

• what is wrong, and where it was found (stage, machine, shift);
• the specification and the actual reading;
• the decision for each piece;
• the cause, and the actions to remove it;
• the check and the closing sign-off.

One NCDR covers one problem in one lot.

The most important point is this: every bad piece gets a decision. The usual decisions are:

The numbers for rework, deviation, scrap and return must add up to the number of bad pieces. If they do not, a piece has been forgotten.

Never accept a bearing seat, a fit or a safety feature under deviation without written approval. On a bearing seat the honest answer is usually "not at all."

What does the CAPA do?

CAPA means corrective action and preventive action. Three different actions are often mixed up, and that is the main reason problems come back:

• Correction acts on the product. Re-turn the oversize shafts. Check every shaft in the lot.
• Corrective action acts on the cause. Set a tool life in the machine's settings, so the tool is changed before it wears.
• Preventive action removes the same risk elsewhere. Write the tool life on the setup sheet of every job, even the jobs that never had the problem.

A simple test for any CAPA form: if every action on it is rework, sorting or "operator warned," it is not a CAPA. It is a correction with a CAPA number on it.

What do we do in the first hour?

Before the cause is known, protect the customer. Ask four questions:

1. Is the machine still making bad pieces? If yes, stop it and approve the first piece again.
2. Where else could the problem be? Check this lot, the work in process, finished stock, goods already sent, and any other machine on the same job.
3. Is it tagged and kept apart? No suspect piece moves on without a written decision.
4. Does the customer need to know? If anything doubtful has gone out, call the same day. A customer who hears from you first is far more forgiving.

A small worked example

This is an example, with made-up figures. An inspector checks 60 shafts and finds 14 out of length tolerance. The decisions are 9 reworked, 2 scrapped and 3 used under deviation with the customer's approval. 9 + 2 + 3 = 14, so every piece has a decision.

The cause, found by asking why step by step: the chuck pressure was low after a service, and the setup sheet gave no pressure to check. Actions: reset the pressure, add the pressure to the setup sheet (corrective), and add a pressure check at the start of every shift on all lathes (preventive).

Rework time and scrap together cost about Rs. 1,650 in this example. Had the same 14 shafts reached the customer, the cost would have been many times higher.

Fixing the part tells you what happened. Fixing the cause makes sure it does not happen again.

How to start in your plant

1. Use one NCDR form for all NC lots, at inward, in-process and final inspection.
2. Insist that every bad piece gets a decision and the numbers add up.
3. Set a trigger for a CAPA, such as a customer complaint, a repeat problem, or a bad rate above a limit you choose.
4. Find the cause with a proper method, such as the 5 Why. Look at both why the defect was made and why it was not caught.
5. Close the CAPA only after the problem has stayed away for a full month.
6. Count your NCs every month, so the owner can see the trend.