What is 8D?

Manufacturer always strive to deliver good quality products, however, when a complaint is received, more often than not, customer are willing to work with their supplier to achieve common goal which is to find root cause, mitigate the current issue and prevent them from recur.  Corrective action report is often used to ensure these activities are recorded and documented in proper manner.
Corrective action and Preventive action (CAPA) can be addressed in several format, most popularly request by customer is an 8D.  They are most comprehensive CAPA available and widely used by automotive industry.  Simply because it covers all the IATF requirement in section:
6.1.2.2  Preventive action
8.7 Control of non-conforming process outputs, products and services 

8D is short for 8 disciplines
0D
Define pre-requisite such as affected product, PO/SO#, owner, reporter, manufacturing plant, total product sent, total affected parts etc.

2D
Establish a team- Establish relevant owner from different function which would be a great source of knowledge and ideas during brainstorming session.  Yes, we sometimes hate to pull people away from their job, we are know they love their job and it's really hard to get away 😆 but it is necessary.  No, we don’t need to call in food every time we have a meeting, but I have to admit, you get full attendance if you do, just saying. 

Yeap, my kinda team. 😎

3D
Problem description, lot#, where it happened, what is the issue (may use the what, when, who, why,  and how method) 

4D
Interim Containment - locate all suspected products either at store, in-transit, customers site or on the field.  Be sure to check every area where the parts may have been transported to, or stored at or still waiting to be processed.

5D
Root Cause Analysis- Investigates how issues might occur through Fishbone method (also known as Ishikawa diagram or cause and effect diagram, this is part of 7 QC tool), you may also use the 5 whys method. 

This gets tedious but you have to exhaust all ideas until you kind of ran out of it.  For example,  Machine is faulty, why? Because the gear was damaged, why? Well because there was a nick on every revolution within the gear, why? Because sharp debris scrapped the wheel off during machining process....  

Figuring out how it end up in there...

6D
Solution and Verification- solutions can be training, new or change in procedures, design change, machines or process improvements. Best to match solution with root cause that was determined earlier so you cover all potential problems.

Ditto

7D
Preventive action to ensure proper doesn’t recur. This could be done by extending the solution to other product family or similar machines. (Eg.-Poka-Yoke, tool change, added software etc)

8D
Congratulate team.  Perhaps acknowledging them during monthly meeting or company newsletter.

Pretty much it!