Select sample articles randomly from each inspection lot. For
small inspection lot, select at least 3 samples to measure their
coating thickness;
for large inspection lot, select at least 5 samples from each
500 products. If necessary, specific test could be taken
according to sampling proportion required by buyers. |
Select 3 local area of 20mm² randomly from both ends and the middle of each
sample. (When the major surface area is too small, put some articles together to
make the total major surface area be larger than 10cm²). Measured thickness of
the local area for 5 times and get 5 records, calculate the arithmetic mean of
these 5 records to get the thickness of the local coating. Then calculate the
arithmetic mean of the thickness of three local areas to get the average coating
thickness of the article.
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