The structure of plastic injection mold 4.2

plastic injection mold

A plastic injection mold is a relatively complicated tool for making plastic products. The manufacturing material of plastic injection mold is steel, which takes a long time to manufacture and costs relatively high. Today we will introduce the five major systems of plastic injection molds.

Plastic molds can be divided into: pouring system, molding system, cooling system, exhaust system, ejection system.

1. Pouring system

The plastic mold gating system refers to the part of the runner before the plastic enters the cavity from the nozzle, including the main runner, cold material cavity, runner and gate, etc.

The main channel refers to the section from the point where the nozzle of the injection machine is in contact with the mold to the runner.The end face shape of the sprue is usually round,In order to facilitate demolding, the sprue is generally produced with a slope, but if the sprue passes through multiple boards at the same time, be sure to pay attention to the slope and size of the holes on each block. The design of the size of the sprue should be determined according to the flow characteristics of the plastic material.

The cold material hole is used to store the cold material head generated during the injection interval, to prevent the cold material from entering the cavity and affecting the quality of the plastic parts, and to make the molten material fill the cavity smoothly. The cold material hole is also called a cold material well.

The runner refers to the section between the main runner and the gate. It is the transition section where the molten plastic flows into the cavity from the main runner and is also the transition section in the gating system through the change of the cross-sectional area and the plastic turning, so that the plastic can be converted smoothly.

The gate is also called the feed port or the inner runner. It is the narrow part between the runner and the plastic part, also known as the shortest part of the gating system. It can accelerate the flow rate of the molten plastic conveyed by the runner, form an ideal flow state, fill the cavity in sequence, and quickly, and also play the role of sealing the cavity to prevent the backflow of the molten material, and it is convenient to use after molding. The gate is separated from the plastic part.

2. Forming system

Plastic mold forming parts system refers to the combination of various parts that form the shape of the product, including movable mold, fixed mold and cavity (concave mold), core (punch mold), forming rod, etc. The core forms the inner surface of the article, and the cavity (die) forms the outer surface shape of the article. After the mold is closed, the core and the cavity constitute the cavity of the mold.

3. Guidance system

The plastic mold guide system is established to ensure that the movable mold and the fixed mold can be accurately aligned when the mold is closed, and guide parts must be installed in the mold. In the injection mold, four sets of guide posts and guide sleeves are usually used to form the guide parts, and sometimes it is necessary to set the inner and outer cone surfaces that match each other on the movable mold and the fixed mold to assist positioning.

4. Cooling system

In order to meet the requirements of the injection process for the mold temperature, a temperature adjustment system is required to adjust the temperature of the mold. For injection molds for thermoplastics, the cooling system is mainly designed to cool the mold, and the mold can also be heated.

5. Ejection system

Plastic mold ejection system generally includes: thimble, front and rear thimble plates, thimble guide rods, thimble return springs, and thimble plate locking screws. When the product is formed 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 runner are pushed out or pulled out of the mold cavity and runner position by the ejector mechanism and the ejector pin under the push of the ejector pin of the injection molding machine. for the next injection molding work cycle.

Because of the complexity of plastic molds, it takes a long time to manufacture plastic molds, usually 20 working days, and the manufacturing cost of molds is also relatively high. In addition, because the mold itself is relatively heavy, it is more troublesome to install and disassemble the mold, which makes the injection molding parts have MOQ requirements during production.

Hongfa promises to only produce regular molds, not simple molds. Therefore, the service life of the injection mold can be guaranteed to be at least 300,000 times. The injection molding raw materials of the plastic shell are all new ABS/PC materials. If you need to make plastic molds or plastic enclosure products, please feel free to contact us.



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