Detection (D) : Detection is the rank associated with the best detection control listed in the process control. In order to achieve a lower ranking, generally the planned process control has to be improved.
Assumed the failure has occurred and then assess the capabilities of all “Current Process Controls” to prevent shipment of the part having this failure or defect. Do not automatically presume that the detection ranking is low because the occurrence is low, but do assess the ability of the process controls to detect low frequency failure or prevent them from going further in the process.
Random quality checks are unlikely to detect the existence of an isolated defect and should not influence the detection ranking. Sampling done on statistical basis is a valid detection control.
Table 3. Suggested Process Failure’s Detection Evaluation Criteria
| Detection | Criteria | Inspection Types | Suggested Range of Detection Methods | Ranking | ||
| A | B | C | ||||
| Almost Impossible | Absolute certainty of non detection | | | X | Cannot detect or is not checked | 10 |
| Very Remote | Controls will probably not detect | | | X | Control is achieved with indirect or random checks only | 9 |
| Remote | Controls have poor chance of detection. | | | X | Control is achieved with visual inspection only. | 8 |
| Very Low | Controls have poor chance of detection. | | | X | Control is achieved with double visual inspection only. | 7 |
| Low | Controls may detect | | X | X | Control is achieved with charting methods, such as SPC. | 6 |
| Moderate | Controls may detect | | X | | Control is based on variable gauging after parts have left the station, or Go/No Go gauging performed on 100% of the parts after parts have left the station. | 5 |
| Moderately High | Controls have a good chance to detect | X | X | | Error detection in subsequent operations, OR gauging performed on setup and first-piece check (for set-up causes only) | 4 |
| High | Controls have a good chance to detect | X | X | | Error detection in-station, or error detection in subsequent operations by multiple layers of acceptance: supply, select, install, verify. Cannot accept discrepant part. | 3 |
| Very High | Controls almost certain to detect. | X | X | | Error detection in-station (automatic gauging with automatic stop feature).Cannot pass discrepant part. | 2 |
| Very High | Controls certain to detect. | X | | | Discrepant parts cannot be made because item has been error-proofed by process/product design. | 1 |
Inspection Types :
A . Error-proofed
B. Gauging
C. Manual Inspection
Articles from FMEA Third Edition DaimlerChrysler Corporation, Ford Motor Company, General Motors Corporation.
