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Detailed explanation of six systems of plastic mold

The functional structure of the plastic mold system is mainly composed of six systems: gating system, temperature regulating system, molding parts system, exhaust system, guiding system and ejection system. The gating system and molding parts are the parts that directly contact with the plastic and change with the plastic and products. They are the most complex and changeable parts in the plastic mold and require the highest machining finish and precision.

1. Gating system:

Gating system refers to the part of the runner before the plastic enters the cavity from the nozzle, including the sprue, cold cavity, splitter and gate.

2. Forming parts system:

Forming parts system refers to the combination of various parts forming the shape of products, including moving die, fixed die, cavity (female die), core (male die), forming rod, etc. The core forms the inner surface of the product, and the cavity (die) forms the outer surface shape of the product. After clamping, the core and cavity form the cavity of the mold. According to the process and manufacturing requirements, sometimes the core and die are composed of several pieces, sometimes they are made as a whole, and only inserts are used in the parts that are easy to damage and difficult to process.

3. Temperature regulating system:

In order to meet the requirements of injection process for mold temperature, the temperature regulating system is needed to adjust the mold temperature. For thermoplastic injection mold, the cooling system is designed to cool the mold (or heat the mold). The common method of mold cooling is to set up cooling water channel in the mold, and use the circulating cooling water to take away the heat of the mold; in addition to using the cooling water to pass hot water or hot oil, the mold can also be heated by installing electric heating elements inside and around the mold.

4. Exhaust system:

The exhaust system is set up to exhaust the air in the injection molding cavity and the gas produced by the plastic melting to the mold. When the exhaust is not smooth, the surface of the product will form gas marks (gas lines), scorch and other defects. The exhaust system of the plastic mold is usually a groove shaped air outlet in the mold, which is used to exhaust the air in the original cavity and the gas brought by the molten material.

When the molten material is injected into the cavity, the air in the cavity and the gas brought in by the melt must be discharged to the outside of the mold through the exhaust port at the end of the material flow, otherwise, the product will have pores, poor connection, insufficient filling, and even the accumulated air will burn the product due to high temperature caused by compression. In general, the vent can be set at either the end of the melt flow in the mold cavity or the parting surface of the mold.

The latter is to open a shallow groove with a depth of 0.03-0.2mm and a width of 1.5-6mm on one side of the die. During injection, there will not be a lot of molten material seeping from the exhaust hole, because the molten material will cool and solidify there, blocking the channel. The opening position of the exhaust port should not face the operator, in order to prevent accidental spraying of molten material to hurt people. In addition, the fit clearance between the ejector rod and the ejector hole, the fit clearance between the ejector block and the demoulding plate and the core can also be used to exhaust.

5. Guidance system:

The guiding system is set up to ensure that the moving die and the fixed die can be accurately aligned when closing the die. In the injection mold, four groups of guide pillars and guide sleeves are usually used to form the guide parts, and sometimes it is necessary to set the inner and outer conical surfaces on the moving mold and the fixed mold respectively to assist the positioning.

6. Ejection system:

Ejection system generally includes: thimble, front and rear thimble plate, thimble guide rod, thimble return spring, thimble plate locking screw, etc. When the product is molded and cooled in the mold, the front and rear molds of the mold are separated and opened, and the plastic product and its condensate in the flow channel are pushed out or pulled out of the mold cavity and the flow channel position by the ejector mechanism -- the thimble under the push of the ejector rod of the injection molding machine, so as to carry out the next injection molding cycle.

After reading the above six systems of plastic mold system, I believe you have explained the six systems of plastic mold in detail.

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