Tinplate is generally ordered from regular manufacturers according to standards, such as JIS3303 or enterprise standards. Generally speaking, there are several kinds of contracted products. One is the defective products or waste products bought in the spot market, usually at a lower price, but the quality is usually no longer guaranteed by defects, and the use losses caused by defects are no longer treated and compensated; The other is to order futures contracts, but not according to the standards. For example, if there are special requirements that are inconsistent with the standards, it is necessary to sign a supply agreement with the supplier. Generally speaking, the agreed product refers to the former.