Due to the different uses of each product, the processing technology and quality requirements of raw materials are also different. Generally speaking, different stainless steel products require different thickness tolerances of raw materials, such as second-class tableware and thermos cups, etc., the thickness tolerance is generally higher, which is -3~5%, and the thickness tolerance of first-class tableware generally requires – 5%, steel pipes require -10%, hotel freezer material thickness tolerance requirements are -8%, dealers generally require thickness tolerances between -4% and 6%. At the same time, the difference in domestic and foreign sales of products will also lead to different requirements of customers on the tolerance of raw material thickness. Generally, export product customers have higher thickness tolerance requirements, while domestic sales companies have relatively lower thickness tolerance requirements (mostly due to cost considerations), and some customers even require -15%.
①DDQ(deep drawing quality) material: refers to the material used for deep drawing (punching), that is, the so-called soft material. The main characteristics of this material are high elongation (≧53%) and low hardness (≦170 %), the internal grain grade is between 7.0 and 8.0, and the deep drawing performance is excellent. Many companies that produce thermos bottles and pots have a processing ratio of their products (BLANKING SIZE/product diameter) are generally relatively high, and their processing ratios reach 3.0, 1.96, 2.13, and 1.98 respectively. SUS304DDQ materials are mainly used for products that require a higher processing ratio. Of course, products with a processing ratio exceeding 2.0 generally need to be stretched several times to complete. If the raw material extension cannot be achieved, the product is prone to cracks and pull-through phenomena when processing deep-drawn products, which will affect the qualified rate of finished products, and of course increase the cost of the manufacturer;
②General material: mainly used for materials other than DDQ. This material is characterized by relatively low elongation (≧45%), relatively high hardness (≦180HB), and internal grain size grades of 8.0~9.0 Compared with DDQ materials, its deep drawing performance is relatively poor. It is mainly used for products that can be obtained without stretching, such as spoons, spoons, forks, electrical appliances, and steel pipes for tableware. But it has an advantage compared with DDQ material, that is, the BQ property is relatively better, which is mainly due to its slightly higher hardness.
Stainless steel sheet is an inexpensive material, but customers have very high requirements on its surface quality. In the production process of stainless steel sheet, there will inevitably be various defects, such as scratches, pits, sand holes, dark lines, creases, pollution, etc., so its surface quality, such as scratches, creases, etc. It is not allowed to appear, and defects such as pitting and sand holes are never allowed in the production of spoons, spoons, forks, because it is difficult to throw them away when polishing. It is necessary to determine the surface quality level according to the degree and frequency of various defects on the surface, so as to determine the product level.