What is the difference between an open hot runner and a needle valve hot runner?
Hot runner hot nozzle classification: open hot runner hot nozzle (for micro semi-hot runner), needle valve hot runner hot nozzle (for adiabatic runner).
The structure of the open hot runner is generally relatively simple. It is suitable for micro-semi-hot runners. Generally, it can not be used in adiabatic runners. The adiabatic runners have high limitations on materials and are directly exposed to the surface of the product. Drawing and leakage, the surface quality is poor; the micro semi-hot runner does not touch the product but is in contact with the micro flow passage, so the open hot nozzle can be used, and it is widely used in high-precision molds abroad. The open hot runner hot nozzle has a large amount of glue, simple structure and convenient installation, and the requirements for some product appearance parts are not very high.
Hot runner hot nozzle classification: open hot runner hot nozzle (for micro semi-hot runner), needle valve hot runner hot nozzle (for adiabatic runner). The structure of the open hot runner is generally relatively simple. It is suitable for micro-semi-hot runners. Generally, it can not be used in adiabatic runners. The adiabatic runners have high limitations on materials and are directly exposed to the surface of the product. Drawing and leakage, the surface quality is poor; the micro semi-hot runner does not touch the product but is in contact with the micro flow passage, so the open hot nozzle can be used, and it is widely used in high-precision molds abroad. The open hot runner hot nozzle has a large amount of glue, simple structure and convenient installation. The requirements for some product appearance parts are not very high, and the plastic melt with poor fluidity has good effects. ??
The open hot runner has many special types of glue mouths. The hot mouth of the hot runner has no cold material, the rubber mouth is very small, and the rubber mouth is glued out. It is punctiform. It can effectively improve the shear of plastic melt. The rate reduces the viscosity of the melt, which makes the filling easy, and can be used for injection molds of single or multi-cavity, suitable for plastics such as PE, PP, PS, ABS. The mouth of the open mouth nozzle is straight through, the nozzle surface is left on the product surface, and it has excellent color change ability. For large products or small high-density engineering plastic molds and HDPE or other poorly flowing plastics. Can achieve good injection molding results. The needle valve type needle valve type hot runner saves materials, the surface of the plastic parts is beautiful, and the internal quality is tight and the strength is high. There are two major categories in the world?
Needle valve hot runner needle valve hot runner (according to injection principle): cylinder type and spring type. The cylinder type controller and timing controller control the cylinder to push the needle valve to close, the structure is more complicated, but the design itself is simple. The flow path of the needle-type hot runner is integrated with the cylinder, and the structure is very compact, so that the space occupied by the mold frame can be greatly reduced, the mating position structure is single, the installation is convenient, the minimum gap of the rubber joint is traced, and the pouring time can be shortened. Improve product production efficiency and other effects.
These are simple introductions. In fact, opening a hot runner is based on the size of the plastic part, the materiality, the presence or absence of corrosiveness, the addition of no fiber, and the flame retardant.
Classification of hot runner nozzles
The hot runner mold directly determines the hot runner system selection and the design and manufacture of the mold according to the nozzle structure. The hot runner system is designed and manufactured in different ways. The types are similar, but the processing technology and implementation method of each manufacturer are very different, so that the hot runner The quality and price of the system vary widely.
There are three types of hot nozzles:
First, open hot nozzle
Second, external heating
3. Needle valve type hot nozzle: The needle valve type nozzle is technically advanced, and the main advantages are:
(1) No in-situ residue marks are left on the product, and traces at the entrance gate are smooth;
(2) The use of larger diameter gates can speed up cavity filling and further reduce injection pressure and reduce product distortion.
(3) It can prevent the phenomenon of wire pulling and runny when opening the mold;
(4) When the screw of the injection molding machine is retracted, the material can be effectively prevented from being sucked back from the cavity;
(5) It can be combined with sequential control to reduce the weld line of the product.
Since the form of the hot nozzle directly determines the selection of the hot runner system and the design and manufacture of the mold, the hot runner system is often divided into an open hot runner system and a needle valve hot runner system.
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