How to choose raw materials for precision stamping parts processing?
The selection of raw materials for precision stamping parts directly determines the forming accuracy, mechanical properties and service life of products. It is necessary to screen the stamping performance, dimensional accuracy and surface quality of materials around the three core dimensions of stamping process characteristics, product functional requirements and cost control. The specific selection methods are as follows:
First, give priority to the core selection basis.
Stamping process type
Shallow stretching/bending parts (such as electronic connectors and hardware supports): focus on the ductility and bending resilience of materials;
Deep-drawn parts (such as battery case and automobile fuel tank liner): the materials should have high plasticity, low yield strength and uniform grain structure to avoid tensile cracking;
Precision blanking parts (such as gear blades and sensor shrapnel): It is required that the material hardness is uniform and the thickness tolerance is small, so as to ensure that the blanking section is flat and burr-free.
Working conditions of products
Mechanical structural parts (such as automobile chassis stamping parts): high tensile strength and high yield strength are required;
Conductive/heat-conducting parts (such as electrical contacts and heat sinks): copper, aluminum and other materials with excellent conductivity and heat conductivity are preferred;
Corrosion-resistant parts (such as outdoor hardware, bathroom stamping parts): stainless steel, galvanized steel plate and other rust-proof materials are needed;
High-precision elastic parts (such as spring pieces and buckles): materials with stable elastic modulus such as spring steel and phosphor bronze are selected.
Cost and mass production adaptability
Mass civilian products: cold-rolled steel plate (SPCC) and hot-rolled steel plate (Q235) with high cost performance are preferred;
High-end precision products: high-performance materials such as stainless steel (304/316L), copper alloy and aluminum alloy are selected.
Second, the classification and application scenarios of common precision stamping raw materials
The material category represents the core characteristics of the brand and is suitable for precision stamping parts.
Cold-rolled steel plates SPCC, SPCD and SPCE have smooth surfaces, small thickness tolerance (±0.01~0.03mm), good ductility, and flat blanking sections, such as electronic component brackets, internal structural parts of household appliances and lightly drawn hardware.
DC01, DC03 and DC04 special steel plates for deep drawing have low yield strength, excellent plasticity, fine grain and strong tensile cracking resistance. Automobile oil tank, battery shell and complex curved surface drawing parts.
Stainless steel 304, 316L and 430 have strong corrosion resistance and high hardness, 304 has good ductility and is suitable for stretching, and 316L is acid and alkali resistant outdoor precision hardware, medical device stamping parts and bathroom accessories.
Copper and copper alloys: red copper (T2), brass (H62) and phosphor bronze (C5191) have excellent electrical and thermal conductivity, and phosphor bronze has good elasticity and fatigue resistance. Electrical contacts, connector shrapnel, heat sinks and precision springs.
Aluminum alloys 1060, 3003 and 5052 are lightweight, good in corrosion resistance, good in ductility of 1060, and high in strength of 5052. Lightweight stamping parts, mobile phone shells and heat dissipation structural parts for new energy vehicles.
Spring steel 65Mn and SK5 have high elasticity, high hardness, fatigue resistance and stable performance after heat treatment. Precision spring plates, buckles and clutch plates.
Third, control the performance indicators of key materials
Stamping performance index
Elongation (δ): the higher the ductility, the better, and the elongation of deep-drawn parts should be ≥30% (for example, the elongation of DC04 can reach more than 40%);
Yield ratio (σs/σb): the smaller it is, the more suitable it is for drawing, and the yield ratio of deep-drawn steel plate is ≤0.6 to avoid necking during drawing;
Hardness (HV/HRB): moderate hardness is appropriate, too high is easy to crack, too low is easy to stick to the mold, and the hardness of precision blanking parts is controlled at HRB 50~70.
Size and surface accuracy index
Thickness tolerance: precision stamping parts require material thickness tolerance ≤ 0.01 ~ 0.03 mm to avoid dimensional deviation of stamping parts caused by uneven thickness;
Surface quality: the surface of raw materials should be smooth and free of scratches, scales and impurities, otherwise it will be inherited to the surface of stamping parts, which will affect the subsequent electroplating and spraying effects.
Other characteristic requirements
Surface roughness: the surface roughness Ra of cold-rolled steel plate is less than 0.8 μ m, which ensures the smooth contact between the material and the die during stamping;
Flatness: the warpage of the material is ≤1mm/m, so as to avoid material jamming during feeding and ensure the stamping positioning accuracy.
Four, special working conditions of material selection skills
High wear-resistant precision parts: stainless steel 420 or carburized cold-rolled steel plate is selected, and the hardness is improved by heat treatment after stamping;
Low temperature environment parts: choose nickel steel or austenitic stainless steel (304) to avoid brittle fracture at low temperature;
Food-grade/medical-grade parts: 304/316L stainless steel and T2 copper shall be selected, which shall meet the certification standards of FDA or medical industry.
