Has something been missed here? Is the process capable of meeting the customers specifications? This is an everyday problem. An order is accepted for a product, but no one has determined that the process can meet the customers needs or specifications.
If the normal process can not meet the specifications, nothing less than 100% inspection, or selecting, of the parts will meet the customers requirements. A process can be in statistical control and not meet specifications. This is an engineering problem that all too often is transferred to production.
If the process has been proven to meet the specifications and the established sample rate can varify this, why change. To reduce the sample rate, another verification study will have to be made to justify the reduced sampling rate. There will need to be some triggering mechanism to return to the previous sampling rate should the individual samples indicate a change in the normal operation. This is sometimes anticipated by returning to increased sampling rates after any change, such as dies, has been made. Increased sample rates are neede to varify that any repairs made to a system after a break down have returned the system to normal operation.
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