The most important basis for seeing the essence of injection molding through the phenomenon

Hui focuses on consulting and training services for the injection molding industry in China, and is committed to cost reduction and efficiency in the injection ...

Jul 15,2022 | Angle

Hui focuses on consulting and training services for the injection molding industry in China, and is committed to cost reduction and efficiency in the injection molding industry.

Injection molding machine, or injection molding machine, consists of small business online payment processingthree important parts: injection system device, mold closing device and injection mold. Injection molding machine specifications are expressed in two ways: one is the maximum volume or weight we can inject each time, and the other is the maximum clamping force. The injection molding machine carries out the other main technical parameters of the enterprise for the plasticizing behavior capacity, injection rate and injection working pressure.

Injection unit

The main component of the injection molding machine. The plastic is heated and plasticized into a flowing state and injected into the mold under pressure. Injection methods are plunger type, preplasticized type and reciprocating screw type. The latter has uniform plasticization, low injection pressure loss, compact structure and is widely used.

Mold Closing Device

The fixed mold and the moving mold close the mold to realize the opening rapid moldingand closing action and ejection of the finished product.

Injection Molding

Abbreviated as injection molding. It consists of pouring system, molding parts and structural parts.

① The pouring operation system is the flow development channel of plastic enterprise from the injector nozzle to the cavity.

2) Molding parts are the parts that form the cavity of the mold and consist of the negative mold and the positive film.

3 structural parts, including guiding, film taking, core extraction, typing and other parts. The mold is divided into two parts, fixed mold and moving mold, which are fixed on the fixed plate and moving plate of the clamping device. The mold can be heated or cooled as needed.

Operation method

It varies according to the material to be processed. Injection molding of thermoplastics includes charging, plasticizing, injecting, holding pressure, cooling and demolding. The molding of thermosets m30s++and rubbers includes the same process, except that the barrel temperature is lower than that of thermoplastics, but the injection pressure is higher and the mold is heated. After injection, the material needs to be cured or vulcanized in the mold, and then the film is uncovered while it is hot.

Injection molding is to have a certain different shape of the model, through learning pressure will melt state of the colloid into the touch cavity and molding, the basic principle of the process is: the solid plastic company in accordance with the enterprise certain melting point melting, by carrying out injection as well as machine pressure, with a certain speed development into the Chinese mold, the mold mainly through the artificial waterway cooling will be plastic curing and get the same product as the design cavity.

Injection molding (injection molding) is a method of uniformly plasticizing a thermoplastic or thermoset molding compound in a heated barrel and then pushing it into the cavity of a closed mold by means of a plunger or moving screw.

Injection molding is used for almost all thermoplastics. Injection molding has also been successfully used to mold certain thermoset polymers. The injection molding cycle time is short (seconds to minutes), product quality can range from a few grams to tens of kilograms, complex shapes can be molded in a single pass, and precise dimensions can be achieved with metallic or non-metallic inserts. Therefore, the method is highly adaptable and productive.

The injection molding machine is divided into plunger type injection molding machine and screw type injection molding machine, which consists of injection system, clamping system and plastic mold.

Their molding methods can be divided into.

(1) Venting injection technology molding.

An exhaust injection molding machine for exhaust injection molding applications has an exhaust port in the middle of the barrel and is connected to a vacuum system. The vacuum pump can extract the mixed water vapor, monomer, volatile substances and air from the plastic through the exhaust port, and the raw materials do not need to be pre-dried, thus improving production efficiency and product quality. It is especially suitable for molding of hygroscopic materials such as polycarbonate, nylon, organic glass and cellulose.

(2) Flow injection molding.

Flow injection molding can be done with a common mobile screw injection machine. That is, the plastic is continuously plasticized and squeezed into the mold cavity at a certain temperature. When the plastic fills the cavity, the screw stops rotating. Flow injection molding overcomes the equipment limitations of producing large products, and the part mass can exceed the maximum injection volume of the injection molding machine. It is possessed the property of plasticizing the object not by storing it in a barrel, but by continuously extruding it into the mold, so it is a combination of extrusion and injection method.

(3) Co-injection molding.

Co-injection molding is a method of injecting different types or colors of plastics into a mold simultaneously or sequentially by using an injection machine with two or more injection units. This method allows the production of composite products of various colors and plastics. Typical co-injection molding methods are two-color injection and multi-color injection.

(4) Flowless injection technique molding.

In this molding method, the molten material is distributed directly into each cavity through the extension nozzle of the injection molding machine without the branch channels set in the mold. During the injection process, the plastic in the runner remains in molten flow and does not flow out with the product during the demolding process, so there is no runner residue in the product. This molding method not only saves raw materials and reduces costs, but also reduces the process and can realize fully automatic production.

(5) Reaction injection molding.

The principle of reaction injection molding is to inject the reaction raw materials measured by the meter into the mixing head, contact and mix at the mixing head, and then inject into the sealed mold at high speed to quickly cure, demold and remove the product. It is suitable for processing polyurethane, epoxy resin, unsaturated polyester resin, silicone resin, alkyd resin and other thermosetting polymers and elastomers. Mainly used for the processing of polyurethane.

(6) Injection molding of thermosetting plastics.

Granular or agglomerated thermosetting plastics, in strict management control of the ambient temperature of the barrel, through the role of different screws, plasticized into a viscoplastic state, in the higher injection working pressure, the material can enter the enterprise a certain influence on the temperature distribution range of the mold cross-linking curing. Thermosetting plastics for injection molding in addition to physical learning state changes, there are some chemical development changes. Therefore, compared with thermoplastic injection molding, there is a big difference in the molding system equipment and processing production process. The following table analyzes and compares the differences between thermoset and thermoplastic injection molding.