There are three main types of Sheet Metal Processing: punching, bending, and stretching. Different processing techniques have different requirements for sheet metal. The selection of sheet metal should also consider the selection of sheet metal according to the approximate shape and processing technology of the product. The material hedges the influence of cutting processing. Punching requires that the plate should have enough plasticity to ensure that the plate does not crack during punching. Soft materials (such as pure aluminum, rust-proof aluminum, brass, copper, low-carbon steel, etc.) have good punching performance. After punching, parts with smooth cross-section and small inclination can be obtained. Hard materials (such as high-carbon steel, stainless steel, hard aluminum, super-hard aluminum, etc.) have poor quality after punching, and large cross-section irregularities, which are particularly serious for thick plates. For brittle materials, it is easy to produce tearing phenomenon after punching, especially when the width is very small, it is easy to produce tearing. The influence of materials on bending processing requires that the sheet formed by bending should have sufficient plasticity and low yield limit. Plates with high plasticity are not easy to crack when bending. Sheets with lower yield limit and lower elastic modulus have small rebound deformation after bending, and it is easy to obtain a curved shape with accurate dimensions. Low-carbon steel, brass, and aluminum with a carbon content of less than 0.2% are easy to bend and form; brittle materials, such as phosphor bronze (QSn6.5~ 2.5), spring steel (65Mn), hard aluminum, superhard aluminum, etc., must have a large relative bending radius (r/t) when bending, otherwise cracking is prone to occur during the bending process. Special attention should be paid to the choice of the hard and soft state of the material, which has a great impact on the bending performance. For many brittle materials, bending will cause cracking or even bending fracture at the outer angle. There are also some steel plates with high carbon content. If the hard state is selected, bending will also cause cracking at the outer angle or even bending fracture. These should be avoided as much as possible. The influence of materials on stretching processing, plate stretching, especially deep stretching, is one of the more difficult in sheet metal processing technology. It not only requires the depth of stretching to be as small as possible, the shape to be as simple and smooth as possible, but also requires the material to have good plasticity. Otherwise, it is very easy to cause the overall distortion and deformation of the part, local wrinkling, and even tensile cracking. The yield limit is low and the directivity coefficient of the plate thickness is large. The smaller the yield ratio of the sheet metal, the better the stamping performance and the greater the limit degree of one-time deformation. When the directivity coefficient of the plate thickness is > 1, the deformation in the width direction is easier than the deformation in the thickness direction. The larger the R value of the tensile fillet, the less likely it is to thin and break during the tensile process, and the better the tensile properties. Common materials with better tensile properties are: pure aluminum sheet, 08Al, ST16, SPCD. The influence of materials on stiffness, in the design of sheet metal structures, it is often encountered that the stiffness of sheet metal structural parts cannot meet the requirements. Structural designers often replace low carbon steel with high carbon steel or stainless steel, or replace ordinary aluminum alloy with hard aluminum alloy with high strength and hardness. It is expected to improve the stiffness of parts, but in fact there is no obvious effect. For the same substrate material, heat treatment and alloying can greatly improve the strength and hardness of the material, but the change in stiffness is minimal. To improve the stiffness of the part, only by changing the material and changing the shape of the part can a certain effect be achieved.