There is a variety of options when it comes to implementing a sampling plan for the incoming materials that you receive from your suppliers. The Quality of your inventory and the total cost of the inspection will depend on your selection.
The bad quality of the incoming materials has an expensive cost. Defective parts cause problems in assembly, need for rework, re-inspection, warranty expenses for the return of sold parts, loss of future orders, expenses to regain reputation, and others.
The following table shows the different types of sampling plans that you can choose
From the above sampling plans, continuous sampling is designed to inspect manufacturing processes where there is not lot formation. For example, an inspection of a semi-finished product before the next production stage.
There are several parameters related to the quality of the parts that you receive, and to the number of inspected units that can help you to design the right plan. AQL, AOQL, LTPD, α and β risk are the indicators related to quality. Average Sampling Number (ASN), and Average Total Inspection per lot (ATI) are the concepts related to the number of inspected units. Using these concepts, there is a possibility of selecting a sampling plan for the desired level of quality that minimizes the number of inspected units.
A Manufacturing Engineer can help you to select the right plan that fit your needs and the quality of your incoming materials.