At some point, the manufacturer and the purchaser reach a compromise and agree that if a lot contains more than a certain number of defective components, the lot will be rejected.100 percent inspection is one way to determine the number of defective parts; however, this is a costly process, and the cost of this inspection is recovered in some form or another from the purchaser. Taking all of this into consideration, both parties bring sampling Container Loading Supervision Service into the picture.
Inspection by sampling is a technique for determining whether a lot or population should be rejected or accepted based on the number of defective parts discovered in a random sample drawn from the lot. In cases where the number of defective parts exceeds a predetermined threshold, the lot is returned to the manufacturer.
Without using quantitative measures, attribute inspection is used to distinguish between a defective and a non-defective part, and the part is either rejected or accepted based on its attributes. For example, if a predetermined number of bullets are fired from a sample taken from a lot, the lot is accepted; otherwise, the lot is rejected. It is extremely important, as well as very common, to conduct attribute inspections. A quiet, isolated location away from the production floor can be used for inspection.
First and foremost, attribute inspection is used in situations where components are clearly defective or non-defective. When it is extremely difficult and expensive to measure the quality characteristics of a product, such as when inspecting the paint finish on a refrigerator, the second category is applicable. Third, attribute inspection is used to identify applications where the manufacturer does not believe it is necessary to measure the exact job dimensions and believes that a go or no go type of inspection will suffice - such as shafts, spindles, or rings - in order to accomplish his objectives. When inspecting samples, attributes are used to perform the majority of the quality inspection services.
Consider the following scenario: a (manufactured) lot contains N components. The purchaser would prefer that the lot contain no defective components, but the manufacturer understands that, under normal circumstances, it is unlikely that the defective components will be completely eliminated from the lot.
The details reveal that there is always a degree of uncertainty or probability associated with the sampling inspection when one digs deeper. A sample does not always accurately represent the true condition of the lot, as it can be skewed by the/human element involved in selecting the sample from the lot during the sampling process.
It is possible that the sample will contain all good components by chance, but that the remaining pieces in the lot will contain a large number of defective components, or that all of the sample pieces will turn out to be defective, but that the rest of the lot will be excellent by comparison. Consequently, there is a risk for both the purchaser and the manufacturer in this situation. However, if they decide to conduct a sampling inspection, both parties will be responsible for a certain amount of risk.