Plastic Mold, Injection Molding and Plastic Injection Mold plastic part
Plastic Mold, Injection Molding and Plastic Injection Mold Plastic Part
The principle of injection molding and its process are divided into three stages: plasticizing metering, injection filling and cooling.
The concept of plasticization
What is plasticization?
After the molding material is heated, compacted, and mixed in the barrel of the injection molding machine, the process of converting the loose powder or granular solid into a continuous homogenized melt is called plasticization.
Homogenization consists of four aspects:
The composition in the melt is uniform, uniform in density, uniform in viscosity and uniform in temperature distribution.
Metering: refers to the preparatory action that can be ensured by the injection machine through the plunger or screw, the plasticized melt is fixed, constant pressure, quantitatively output (ie, injected), and these actions require the injection machine to control the plunger. Or the screw is completed during the plasticizing process.
Factors affecting the accuracy of the measurement: 1 the accuracy of the injection machine control system; 2 the barrel is the plasticizing chamber) and the geometrical elements of the screw and its quality impact. (3) Plasticizing effect and plasticizing ability
Plasticizing effect: refers to the degree of homogenization after the material is converted into a melt.
Plasticizing ability: refers to the quality of materials that can be plasticized by the injection machine per unit time.
The plasticizing effect is related to the way the material is heated and the structure of the injection machine:
1Plunger type injection machine, the material can only accept the pushing force of the plunger in the barrel, and it is almost free from shearing. The heat used for plasticizing is mainly obtained from the high temperature barrel equipped with heating device externally.
Screw injection machine, the rotation of the screw in the barrel will strongly agitate and shear the material, resulting in intense friction between the materials, and thus generate a lot of heat, the heat of the material can be simultaneously The friction heat generated from a, high-temperature barrel and itself can also be supplied separately by friction heat alone.
Plasticization effect comparison
a is called ordinary screw plasticization; b is called dynamic melting. Obviously, under dynamic melting conditions, strong agitation and shearing not only facilitates the homogenization of the components in the melt, but also avoids the influence of fluctuating barrel temperature on the melt temperature, which is beneficial to the viscosity of the melt. Homogenization and temperature distribution are homogenized, and a good plasticizing effect can be obtained. When the plunger type injection molding machine plasticizes the material, it can not produce the mixing effect of stirring and shearing, and is affected by the temperature fluctuation of the barrel, so the composition, viscosity and temperature distribution of the melt are relatively low. Its plasticizing effect is not as good as power melting. It is also not as plasticized as a normal screw that relies on the heat of the barrel in the middle state.
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Plastic Mold, Injection Molding and Plastic Injection Mold Plastic part