Inspection Methods & Sampling
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Product Inspections are performed randomly selecting a sample size from the whole consignment. Results are classified as defective or non-defective with respect to given requirements and a type sample. The sampling plan is in line with BS6001 (based on the mathematical theory of probability) which provides a fair balance between the interests of the supplier and purchaser. In a given lot or consignment, it specifies the number of units to be inspected and the maximum number of defectives allowed in that sample. The British Standard 6001 is equivalent to:
There are several levels of inspections appropriate to the different stages of production. The level as well as the consignment size will determine the size of the sample to be randomly selected. The levels used for the 3 pre-shipment inspections are as follows: Initial Production Check (IPC) – Single Sampling Plan General Level I If a tighter inspection plan is needed for special cases where stricter controls are required on the product, level III may be applied. Level III generally means that a larger sample size will be checked, and of which a smaller proportion is allowed to be defective. Level S3 is a special level used in conjunction with Levels I, II and III. Level S3 is used for field tests and performance measurements where it would not be practical to perform such tests on larger sample sizes More information on our Product Inspection Services Defect Classification and Acceptable Quality Level (AQL) Critical: Defects against safety requirement or apt to results in hazardous or unsafe utilisation. Major: Function or appearance defects which will result in the failure or lessen the value/salability of the product. Minor: Defects that are unlikely to reduce the use of the product, but nevertheless may influence the sale or level of returns. The number of Critical, Major and Minor defective units allowed are controlled by the Acceptable Quality Level (AQL) AQL is a number that determines the maximum number of allowable defective units in a sample. AQLs can be considered satisfactorily as a process of average, however it is not a percentage. The consignment size and inspection level determines the size of the sample, although for very small or very large consignment, the AQL can also have an influence on the size of the sample. Different AQLs may be designed for different defects such as critical, major and minor defects. The AQL should be agreed upon between the buyer and supplier, prior to manufacture or delivery of the product. The following AQLs are applied by SGS unless otherwise instructed by the client:
For a copy of A Guide to Quality Control Services for Importers & Exporters please click here or contact us on 020 8991 3410. For more information: |
