The surface and internal properties of sheet metal stamping have a significant impact on the quality of finished products. The requirements for stamping material are:
　　① The thickness is accurate and even. Precision stamping die, the gap is small, sheet metal over the General Assembly to increase the deformation force, and cause the card material, and even the mold burst; sheet is too thin will affect the quality of finished products, and even pull in the deep drawing.
　　② smooth surface, no spots, no scars, no scratches, no surface cracks and so on. All surface defects will remain on the surface of the finished product. The crack defects may expand to the deep and widen due to bending, drawing and forming, resulting in waste products.
　　③ uniform yield strength, no obvious directionality. Anisotropy (see plastic deformation of the sheet in the drawing, flanging, bulging and other stamping process, due to the emergence of each have a yield, plastic deformation is inconsistent, will cause uneven deformation, the formation of inaccurate caused Defective or scrap.
　　④ uniform elongation rate. Tensile test, the specimen began to appear before the phenomenon of neck elongation called uniform elongation. When drawing, the deformation of any area of ??the sheet can not exceed the uniform extension of the material, or uneven deformation may occur.
　　⑤ yield ratio is low. The yield strength of the material and the strength limit is called the yield ratio. Low yield ratio can not only reduce the deformation resistance, but also reduce the tendency of wrinkling when drawing, reduce the amount of rebound after bending, and improve the accuracy of bending parts.
　　⑥ low processing hardening. Work hardening after cold deformation will increase the deformation resistance of the material, so that the deformation is difficult, so the general use of low hardening index plate. However, the material with high hardening index has good plastic deformation stability (ie, the plastic deformation is more uniform), and the local cracking is not easy to occur.
In actual production, commonly used and stamping process similar to the test, such as drawing performance test, bulging performance test materials such as stamping performance test to ensure the quality of finished products and high pass rate.