Besides all listed in the previous post preferences and advantages in adopting the acceptance sampling method in practice for many companies and organizations (industry, trade, transport, etc.), the method also features several disadvantages. These might, in particular situations, make it unsuitable or completely unfit to use. Inherent disadvantages of AS are:
- There are certain risks of accepting defective lots and rejecting good lots.
- More time and effort is devoted to planning and documentation.
- Less information is usually provided about the product.
If we consider, for example some specialized and high-tech manufacturing processes, space and aviation, aerospace industry, microelectronics and all applications where requirements and responsibilities for defective components and products are much higher, AS is not an applicable method. In such applications very strict 100% inspection is usually performed on each individual component, parameter or event. For an aircraft engine, for example, the quality of component parts, parameters, assembly and functioning must be checked more than a single time. In some cases, multiple inspections and tests have to be carried out to prove the required quality and fitness for the purpose. Also, in the production of bearings, the production of balls, rollers, bearing rings involves 100% automated control and ranking in size and class. The same inspection is also involved in the production of a number of elements for the electronics – integrated circuit boards, chips, standard electronic component, etc.
- In developing sampling plans and Operating characteristics (OC) it is possible that in some cases characteristics and diagrams do not provide a clear idea and satisfactory results when errors have occurred in specific indicators, such as lot size N, n, c, etc.
In view of all described above we should exercise great care when adopting the Acceptance sampling method for inspecting (and forecasting) the quality of production, transportation, services, trade and many other fields of application keeping in mind the allowable requirements and acceptable risk of losses and consequences. AS might in some cases lead to conflicts between manufacturers (suppliers) and users (customers). The producer is usually looking for lower possible rejection of manufactured products even when there is a high percentage of defective products in individual lots and the buyer (customer) has the opposite interest – higher possibility for not having defective goods above the agreed percentage and even have reduced percentage of defectives.