Due to the different uses of products, their 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 insulating cups. Thickness tolerances are generally higher, ranging from - 3 to 5%. Thickness tolerances of first-class tableware are generally - 5%, steel pipe is - 10%, thickness tolerances of cold cabinets for hotels are - 8%, and thickness tolerances of distributors are generally between - 4% and 6%. At the same time, the difference between domestic and foreign products will lead to different requirements for material thickness tolerance. Generally, the customers of export products require higher thickness tolerance, while the domestic enterprises require relatively low thickness tolerance (mostly due to cost considerations), and some customers even require - 15%.

 

(1) DDQ (deep drawing quality) material: refers to the material used for deep drawing (punching) purposes, that is, what we call soft material. The main characteristics of this material are high elongation (> 53%), low hardness (< 170%), internal grain grade between 7.0 and 8.0, and excellent deep drawing performance. The processing ratio (BLANKING SIZE/product diameter) of many enterprises producing thermos flasks and pots is generally higher, and their processing ratios are 3.0, 1.96, 2.13 and 1.98, respectively. SUS304DDQ is mainly used for these products with higher processing ratio. Of course, products with processing ratio over 2.0 usually need several times of stretching to complete. If the extension of raw materials is not achieved, the products are prone to crack and break through during deep drawing, which affects the qualified rate of finished products, and of course increases the cost of manufacturers.

 

(2) General materials: Mainly used for materials other than DDQ. This material is characterized by relatively low elongation (> 45%) and relatively high hardness (< 180HB). Its internal grain size is between 8.0 and 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, etc. Use of steel pipe, etc. But it has one advantage over DDQ material, that is, BQ is relatively good, which is mainly due to its slightly higher hardness.

 

Stainless steel sheet is a kind of inexpensive material, but its surface quality is highly demanded by customers. The stainless sheet will inevitably appear various defects in the production process, such as scratches, pitting, sand holes, dark lines, creases, contamination and so on, so that its surface quality, such as scratches, creases and other defects are not allowed to occur in high-grade materials, and such defects as pitting, sand holes are not allowed in spoons, spoons, forks, production, because it is difficult to throw them away when polishing. It is necessary to determine the surface quality grade according to the degree and frequency of surface defects, so as to determine the product grade.