(I) Molds meet working conditions 1, wear resistance When the billet plastically degenerates in the cavity of the mold, it flows and slides along the surface of the cavity, causing violent friction between the cavity surface and the blank, resulting in failure of the mold due to wear. Therefore, the wear resistance of the material is one of the most basic and important properties of the mold. Hardness is the main factor affecting wear resistance. Under normal circumstances, the higher the hardness of the mold parts, the smaller the amount of wear and the better the wear resistance. In addition, wear resistance is also related to the type, number, morphology, size, and distribution of carbides in the material. 2, toughness Most of the working conditions of the mold are very poor, and some often suffer from a large impact load, resulting in brittle fracture. In order to prevent the mold parts from suddenly breaking during work, the mold must have high strength and toughness. The toughness of a mold depends mainly on the carbon content, grain size, and microstructure of the material. 3, fatigue fracture performance During the working of the mold, under the long-term effect of cyclic stress, fatigue fracture often occurs. In the form of small energy multiple impact fatigue fracture, tensile fatigue fracture contact fatigue fracture and bending fatigue fracture. The fatigue fracture performance of a mold depends mainly on its strength, toughness, hardness, and inclusion content in the material. 4, high temperature performance When the working temperature of the mold is higher, the hardness and strength will be reduced, resulting in early wear of the mold or plastic deformation and failure. Because the mold material should have high anti-tempering stability, in order to ensure that the mold at the working temperature, has a higher hardness and strength. 5, cold and hot fatigue resistance Some molds are in a state of repeated heating and cooling during the working process, which causes the stress on the cavity surface to be pulled and the stress changes, causing cracking and peeling of the surface, increasing the frictional force, impeding the plastic deformation, and reducing the dimensional accuracy, resulting in Mold failure. Hot and cold fatigue is one of the main forms of failure of hot work molds, and these types of molds should have high resistance to hot and cold fatigue. 6, corrosion resistance Some molds such as plastic molds work, due to the presence of chlorine in the plastic, fluorine and other elements, after the heat resolved analytical hci, hf and other aggressive gases, erosion mold cavity surface, increase its surface roughness, increase wear and tear failure. (B) mold to meet the process performance requirements The manufacture of molds generally has to undergo several processes such as forging, cutting, and heat treatment. In order to ensure the quality of molds and reduce production costs, the materials should have good forgeability, machinability, hardenability, hardenability, and grindability; it should also have small oxidation, decarburization sensitivity, and quenching. Deformation cracking tendency. 1, forgeability It has low resistance to hot forging deformation, good plasticity, wide forging temperature range, cold cracking in forging and low tendency to precipitate reticular carbides. 2, annealing process The spheroidizing annealing temperature range is wide, the annealing hardness is low, the fluctuation range is small, and the spheroidization rate is high. 3, cutting processability Large amount of cutting, low tool loss, low surface roughness. 4, oxidation, decarbonization sensitivity Antioxidation is good at high temperature heating, the decarburization rate is slow, and it is not sensitive to the heating medium, resulting in a small pitting tendency. 5, hardenability Quenched with a uniform and high surface hardness. 6, hardenability After quenching, a deeper hardened layer can be obtained, which can be quenched with a mild quenching medium. 7, quenching deformation cracking tendency The conventional quenching volume changes little, the shape is warped, the distortion is slight, and the abnormal deformation tends to be low. Conventional quench cracking susceptibility is low, insensitive to quenching temperature and workpiece shape. 8. Grindability The relative loss of the grinding wheel is small, there is no grinding limit for large grinding amount, and it is insensitive to the quality of the grinding wheel and cooling conditions, and it is not prone to wear and grinding cracks. (three) mold to meet the economic requirements In the selection of materials for molds, the principle of economy must be taken into account and manufacturing costs should be reduced as much as possible. Therefore, under the premise of satisfying the use performance, the first choice of low-cost, can use carbon steel will not use alloy steel, can use domestic materials do not have imported materials. In addition, when selecting materials, the production and supply of the market should also be taken into account. The selected steel types should be as small and concentrated as possible and easy to purchase. Selection of automotive stamping die materials Due to the different functions of various components in the mold, the requirements and the selection principles for the materials are also different. Therefore, the rational selection of mold materials is a very important task in the design of stamps. It not only depends on the cost of the parts, but also seriously affects the production. With the development of the automotive industry, people's demand for automobiles is increasing, and the biggest factor that affects production is how to use die materials. Although, the material used for the working parts of the mold should be better than the materials used for other parts. In general, depending on the conditions and requirements of the mold, there are four main types: 1. For mold parts with simple shapes and small stamping parts. Commonly used carbon tool steel, such as T8A, T10A and so on. 2. For the complex shape, the larger the size of the stamping parts of the mold work parts, often with alloy tool steel or high-speed tool steel, such as Cr12, CrWMn, Cr12MoV, W18Cr4V, W6MoSCr4V2 and so on. 2. For die parts that have high stamping accuracy or mold life requirements, carbide or steel cemented carbides are commonly used, such as YG15, YG20, GW50. 3. For large parts (such as car cover die) working parts, common cast iron or cast carbon steel, and some also in the edge of the site to be surfacing reinforcement, such as gray cast iron HT250, cast steel 2G270-500. In the selection of mold parts materials, in addition to the most important selection of the working parts, the more prominent is the guide column, guide sleeve parts, generally selected low-carbon steel carburizing quenching or high-quality carbon steel bearing steel. It must be pointed out that the material selection of the mould working parts is the most important and rigorous, and also that the requirements for the heat treatment industry must be reasonable. In addition to the above parts other mold parts, choose to use carbon structural steel or high-quality carbon steel medium carbon steel on it. Drawing material for deep drawing parts and automobile covers Alloy cast iron or high-strength ductile iron can be selected. Ductile iron can be immersed in lubricating oil. The graphite in the structure has a self-lubricating effect, can effectively reduce the friction in deep drawing, and has a low cost and is easy to process. High-strength ductile iron can be used dual-media delayed cooling martensite austempering to obtain high strength and toughness, hardness 55 ~ 58HRC. The mold is slowly preheated and then heated to 880~900°C. After the insulation, the air is precooled first, and then the brine is quenched to about 550°C and then transferred to the oil cooling. When the mold temperature drops to about 250°C, it is put in 180~200. The hot oil of °C is maintained at an intermediate temperature for 2 to 3 hours, then the oil temperature is reduced to about 170°C for 5 to 7 hours, and finally it is cooled to air cooling. The ductile iron has been alloyed, heat-treated, and surface-treated, and it can be fully used as a car cover stretching die, and the practical use of spheroidal graphite cast iron as a car cover mold is introduced.
The Carbon fiber has been the first choice
for after-market performance parts for a long time because in contrast to
stainless steel and titanium exhausts, carbon fiber has a more modern &
aerodynamic look. As well as being a strong and durable material, carbon fiber
is also very light. It was primarily used in aero-space industry before it
stated being used in automotive industry afterwards.
Carbon Fiber
70% ligter than Steel
40% lighter than Aluminium
35% lighter than Magnesium
50% lighter than SMC
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