A correction is that when a problem and you fix it immediately. For example if a machine is making bad parts because the alignment is wrong and you fix it then it is a Correction. But if you look deeper and find out that the machine has to be aligned after every 4 hours and develop a schedule for it then it is called a Corrective Action.
As ISO 9001 certification looks at production / service in terms of a Process Approach. If there is some problem or a fault then it is a fault in one of the processes. A process is defined as a way in which work gets done. It is a series of steps that if followed consistently delivers the expected output. For example Engineering has a process which results in designs, Manufacturing has a process which results in finished product. Purchasing has a process which results in quality inputs. Sales has a process which results in new orders. Also service companies have their own processes.
A process has to follow a few basic principles to succeed:
- The process must be defined by the planner of the work
- The Process must be understood by the operators
- Process must be easy to carry out
- Process must be measured in order to make a sense of its results
For any process to succeed these four rules must be followed. If any one of these rules is broken then problems arise in the output of the concerned process.
If the process has not been defined in a proper way then it is up to the operator to get it done. Meaning that the process will be done in a different way by each operator.
If the process has not been fully understood then it will cause the operators to develop their own understanding based on trial and error and educated guesses.
If the process is difficult in following because of problems with equipment, schedules, materials, instructions etc. the operators will be forced to work around the system to get the job done which will produces different results for different operators.
If there is no reliable data coming out of the process then nobody will know how well the process is performing and should changes be made to the process or not.
Problems occur when a process goes wrong. For example one time problem occurs due to a single breakdown of a process. When a process consistently breaks one or more of the four rules then recurring problems occur. There are a few basic questions that will guide you is resolving one time or recurring problems. This is known as investigating the Root Cause.
Some questions are as follows:
- Where the process has been formally defined?
- Can the operators demonstrate complete understanding of the said process?
- Can you observe any obstacles to the correct and consistent adherence to the process?
- Is the process consistently meeting requirements as shown by the measurement results?
These four questions are a powerful tool in finding the root cause if you know which process has failed. However as the processes are linked and interconnected, problem occurring in one process may have a root cause in another process. So you have to ask the WHY question repeatedly to arrive at the real root cause.
The Corrective action to undertake is also based on the four questions:
- If the process has not been properly defined then update or create documentation.
- Provide training if the process has not been fully understood.
- Identify and remove problems if there are obstacles to the process
- If the measurements show that the process is incapable of meeting requirements, then re-design the process.
Below is a step by step methodology for Root Cause Analysis and Corrective Action:
First define the problem. You have to make sure that it is not a perceived problem but a real one. You can verify this by writing the problem on a sheet of paper and identify the problem as ?Should be? as compared to ?is? statement. E.g. parts should be chromed, parts were received with golden plating.
Secondly you should define the scope of the problem. Is it just a problem in a particular day?s production or is it a recurring problem.
Thirdly, while you find out a fix for the problem make sure that you have installed checks or stop gap measures to detect the problem if it occurs again.
Fourthly find the root cause of the problem. This can be done by asking the WHY question repeatedly five times and arriving at the real cause of the problem.You can also use the Fish bone Diagram or Ishikawa Diagram for this purpose.
Then you have to plan a Corrective Action to remove the problem and also identify the cost and return on investment. And get the approval for the corrective action from the concerned authority.
Sixthly, you have to implement the corrective action. This can be preventive maintenance of a piece of machinery etc.
Seventhly, after you have made the changes, you have to observe the process again to see if the problem is removed and the real root cause has been removed.