Based on clause 220.127.116.11, the organization shall perform and maintain results as specified by the customer part approval process requirement.
Q: If let say our cpk value get 4.22 during the initial stage and it possible to maintain during mass production. can we request to monitor above 1.33 and get customer approval. if the customer approves, its that okay for the IATF requirement?
The process capability Cpk target should be specified at client CSR - Customer Specific Requirements, or Quality Agreement. If the client does not have to specify the Cpk target, we use the 1.33 target. Examples of Cpk targets identified by customers are 1.33, 1.66 or 2.0.
All Cpk values above 1.33 are positive results. If your process Cpk achieves the value of 4.22 that means very good result. You could monitor your process above 1.33 without request to customer approval.
Following the requirement 18.104.22.168, if you have Cpk bellow 1.33 you should initiate a reaction plan indicated on the control plan and evaluate the impact on compliance to specifications not statistically capable or unstable. This reaction plan shall include containment of product and 100% inspection.
Hi Paulo Salgueiro, Thanks for your explaination. Actually we already get Major NCR during CB audit. The Finding is No evidence to show that the manufacturing process capability or performance for part ######## has been maintained as specified by the customer’s part approval process Initial process capability (i.e during trial run) showed the Cpk result was 1.995 but during the mass production, the Cpk result was 1.424.