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When the steel type (No.) is unknown, we can determine whether it is stainless steel and what kind of stainless steel it belongs to with the help of simple instruments and senses according to the inherent physical and chemical properties of commodities (including whole materials, surplus materials, waste materials and other objects). It should be pointed out that the sensory identification can not distinguish the specific steel (type) number, but can basically distinguish three categories: chromium stainless steel, chromium nickel stainless steel (SUS304, 304) and chromium manganese nitrogen stainless steel (200 Series). The identification methods are as follows: 1. Color…

As we know, the speed of sound refers to the speed of sound. The standard speed is to test the speed of sound propagation in the air at the sea level of 15 ℃ (the speed is different in water or other media). The speed of sonic sound in air at 15 ℃ is 340 meters per second, about 1224 kilometers per hour. Supersonic speed refers to the state that the speed is greater than 340 meters per second. The speed less than 340 meters per second is called subsonic speed. The speed equal to 340 meters per second is…

Traditional manufacturing machines cannot easily integrate a variety of raw materials in the process of cutting or mold forming. With the development of multi-material 3D printing technology, we have the ability to integrate different raw materials. Raw materials that cannot be mixed before will form new materials after mixing. These materials have a wide variety of colors and unique properties or functions. When using 3D printing for the first time, there are various processes and materials to choose, so which process and materials should we choose? There are usually the following considerations: cost, appearance, details, mechanical properties, mechanical properties, chemical…

Classification of titanium alloys according to the data, there are many classification methods. The more common one is to classify according to the metallographic structure after annealing: 1. After annealing, the basic structure is a phase, which is called type a titanium alloy; 2. After annealing, the basic structure is A+B, but mainly a phase, which is called near A-type alloy; 3. After annealing, the basic phase A+B is similar, which is called A+B alloy. It can also be called a equiaxed + B transformation or a primary equiaxed + B transformation or a primary equiaxed + a widmanstatten +…

1、 What is engineering plastics? Engineering plastics are plastics that can be used as engineering materials and replace metals to make machine parts. Engineering plastics have excellent comprehensive properties, high rigidity, low creep, high mechanical strength, good heat resistance and good electrical insulation. They can be used for a long time in harsh chemical and physical environments. They can replace metals as engineering structural materials, but the price is expensive and the output is small. 2、 Classification of Engineering Plastics: Engineering plastics can be divided into general engineering plastics and special engineering plastics. The former mainly includes polyamide, polycarbonate, polyformaldehyde,…

1. What is the purpose of inserting inserts into plastic parts? The purpose of inserting inserts into plastic parts is to improve the local strength, hardness, wear resistance, conductivity and magnetic conductivity of plastic parts, or to increase the stability of the size and shape of plastic parts, or to reduce the consumption of plastic. 2. What is the working principle of single parting surface injection mold? The single parting surface injection mold is also known as the two plate injection mold. As shown in Fig. 5.4, when closing the mold, the moving mold and the fixed mold are closed…

1. What are the preparations before injection molding?  (1) Inspection of raw material appearance and determination of process performance;  (2) Preheating and drying of materials;  (3) . preheating of inserts;  (4) . cleaning of material barrel;  (5) Selection of release agent. 2. What factors limit the size of plastic parts?  (1) Limited by the fluidity of plastics. Under certain equipment and process conditions, the plastic with good fluidity can form larger plastic parts; On the contrary, the size of plastic parts that can be formed is smaller.  (2) The size of plastic parts is also limited by molding equipment. The…

1. What is the dimensional relationship between the nozzle of the injection machine and the sprue of the injection mold? In order to ensure that there is no overflow between the main channel and the nozzle of the injection machine during injection molding, which will affect the demoulding. When designing the mold, the spherical surface at the beginning of the sprue must be slightly larger than the spherical radius of the nozzle head of the injection machine, as shown in Figure 4.10, that is, R is 1 ~ 2mm larger than R. The diameter of the small end of the…

1. Please take the horizontal screw injection machine as an example to describe the working process of the injection machine?  (1) , heating and pre plasticization: driven by the transmission system, the screw will transport and compact the materials from the hopper forward. Under the shear and friction of the heater outside the barrel, the screw and the barrel, the materials will gradually melt, and a certain amount of molten plastic has accumulated at the head of the barrel. Under the pressure of the melt, the screw will slowly retreat. The backward distance depends on the amount required for one…