It is the channel through which the main channel (or shunt) is connected to the cavity. The cross-sectional area of the channel can be equal to the main road (or runner), but it is usually reduced. So it is the smallest section of the entire flow path system.
The shape and size of the gate have a great influence on the quality of the product.
The gate function is:
A, control the speed of the material flow:
B, in the injection can be deposited in this part of the melt early coagulation and prevent backflow:
C, so that the passing of the molten material by strong shear and raise the temperature, thereby reducing apparent viscosity to improve the flow of: D, ease of product and runner system separation. The design of the gate shape, size and position depends on the nature of the plastic, the size and structure of the product. The section shape of the general gate is rectangular or circular, the cross-sectional area should be small and the length should be short, this not only based on the above role, but also because the small gate becomes larger and easier, and the large gate narrowing is very difficult. Gate location generally should be selected in the product is the thickest and does not affect the appearance of the place. The design of the gate size should take into account the nature of the plastic melt. Cavity It is the space for molded plastic products in molds. The components used as constituent cavities are collectively referred to as molded parts. Each molded part often has a dedicated name.
The forming part of the shape of the product is called the concave die (also known as the female mold), forming the inner shape of the product (such as holes, grooves, etc.) called cores or punches (also known as male mould). When designing a molded part, the overall structure of the cavity must be determined based on the performance of the plastic, the geometrical shape of the product, the dimensional tolerances and the use requirements. The next step is to select the position of parting surface, gate and vent hole and demoulding mode according to the definite structure. Finally, according to the size of the control parts of the design and determine the composition of the various parts of the way. The plastic melt enters the cavity to have the very high pressure, therefore the molding part must carry on the reasonable material selection and the strength and the rigidity check. In order to ensure the smooth appearance of plastic products and easy demoulding, where the surface of contact with the plastic, the roughness of the ra>0.32um, and corrosion resistance. Molded parts are generally heat-treated to improve the hardness, and the use of corrosion-resistant steel manufacturing.