Last week we looked upon the operations involved in quality department and the methods they have adopted in their department. In this week we shall move one more step deeper as how the analysis of the data collected is done and how actually Quality Control is achieved.
Last week we have seen that after inspection one has to decide from 4 types decision about the tested item. Out of them if it is Accepted then the item will move ahead for further operations. But if it is not accepted then it should have particular reason for not being accepted. Dimensional variations, Physical Property variations, Mechanical Property variations etc may have caused the item to be not acceptable. The quality inspector has to identify the reason for the non acceptance. This is first level of analysis of the quality of the item produced.
Once the reason is identified the next step is to understand the cause behind the reason. There will be some common reasons of which the cause may be already known. But when the new reason is found then the cause is needs to analyzed. Secondly if a particular reason for the non-acceptance is repeating then also analysis is to be done. This is initial step of Rejction Cause Analysis (RCA)
Once the cause is found the immediate next step is to make the produced item correct. This is called as corrective actions. Items may be reworked to make it further usable or it may be converted to some other item. Immediate actions to remove the cause from doing damage to the produced item and making it acceptable is corrective actions. This is done to ensure production is continuously running and producing acceptable items.
We must understand that corrective actions are only temporary measurements to remove the defect cause. Further steps has to be taken in order not to have same cause in the production. This is called as preventive actions. This is done with complete understanding of whole production process and operating standards of items. This is involves deep study of overall factory operations. Storage of items, handling of items, conveying of items, operator skill level etc will all be be studied and suitable actions will be taken in order to prevent the same cause from occurring again.
In summary Route Cause Analysis Involves 3 steps
1. Finding the Cause of rejection
2. Corrective Actions
3. Preventive Actions
Efficient QC department will actively do RCA in order to ensure quality output of the factory. This is analysis part of non acceptance of inspected items. Here we have considered that the inspecting instruments/gauges and the inspector are able to perfectly compare required measurement and the produced item's measurement. But practically it is not the case. We shall deal with them in next week.
Keep watching space