Plastic injection machine

Short Description:

Mestech is equipped with 30 plastic injection molding machines from 100 tons to 1500 tons and 10 experienced operation technicians. We can provide injection molding products of various sizes for our customers

Product Detail

Plastic injection machine is also called injection molding machine or injection machine. It is the main molding equipment that makes thermoplastic or thermosetting plastic into plastic products of various shapes by using plastic molding molds. The functions of plastic injection molding machine is to heat plastics, apply high pressure to molten plastics, and make them shoot out and fill mold cavity.

I-The classification of  plastic injection molding machine Plastic injection molding machine has the ability to shape plastic products with complicated appearance, precise size or dense texture with metal inserts at one time. It is widely used in national defense, electromechanical, automotive, transportation, building materials, packaging, agriculture, culture, education, health and people's daily life. With the rapid development of plastics industry and the complex structure and functions of the moulding products, different types and specifications of injection moulding machines have been developed accordingly. According to the The precision of products produced, the injection machines can be divided into ordinary and precision injection molding machines. According to power and control system, the injection machine can be divided into hydraulic and all electric injection molding machines. According to the structural form of injection molding machine, there are three kinds: vertical and horizontal (including two color injection molding machine) and angle type.

The introduction to the characteristics of various injection molding machines

5. The general mold-locking device is open around, easy to configure all kinds of automatic devices, suitable for complex, sophisticated products of automatic molding.

6. the belt conveyance device is easy to realize the intermediate installation through the mould, so as to facilitate the automatic production.

7. it is easy to ensure consistency of resin flow and mold temperature distribution in mold.

8. Equipped with rotating table, moving table and inclined table, it is easy to realize insert molding and die combination molding.

9. small batch trial production, the mold structure is simple, low cost, and easy to uninstall.

10. vertical machine because of the low center of gravity, relatively horizontal seismic resistance is better.

1.Horizontal injection molding machine

1.even if the mainframe is low due to its low fuselage, there is no height restriction on the plant.

2.the product can fall automatically, without the use of mechanical hand, automatic molding can also be achieved.

3.because of low fuselage, convenient feeding, easy maintenance.

4.mold must be installed by crane.

5.multiple parallel arrangement, the molded product is easy to collect and pack from the conveyor belt.


2.Vertical injection molding machine

1. the injection device and the clamping device are on the same vertical centerline, and the die is opened and closed along the upper and lower directions. Its floor area is only about half of the horizontal machine, so the conversion into the production area of about twice the production.

2. easy to achieve insert molding. Because the die surface is upwards, the inserts are easy to locate. The automatic insert molding can be easily realized by adopting the type of machine with the lower template fixed and the upper template movable and the combination of the

belt conveyor and the manipulator.

3. The weight of the die is opened and closed up and down by the support of the horizontal formwork. The phenomenon that the formwork can not be opened and closed due to the forward inversion caused by the gravity of the die similar to the horizontal machine will not occur. It helps to maintain the accuracy of machinery and die.

4. By simple manipulator, each plastic cavity can be removed, which is conducive to precision molding.

3.Double injection molding machine

Can one-time injection molding two colors of the injection molding machine, can meet consumer requirements for appearance, users can use the product more comfortable.


4.All electric injection molding machine

All-electric injection molding machine can not only meet the needs of special applications, but also has more advantages than ordinary injection molding machine.

Another advantage of an all-electric injection molding machine is that it reduces noise, which not only benefits workers, but also reduces investment in sound-proof production plants.





5.Angle injection molding machine

The axis of injection screw of angle injection molding machine is perpendicular to the moving axis of clamping mechanism template, and its advantages and disadvantages are between vertical and horizontal. Because the injection direction and the mold parting surface are on the same plane, the angular injection molding machine is suitable for molds with asymmetrical geometry of side gate or products whose molding center does not allow gate marks.

6.Multi station molding machine

The injection device and the clamping device have two or more working positions, and the injection device and the clamping device can be arranged in various ways.


At present, three kinds of injection molding machines are widely used:

Horizontal injection molding machine is widely used because of its small space, convenient installation and wide application range. Double injection molding machines are mostly used for sealing and waterproofing requirements of electronic products, shock buffering electrical tools, and products with a variety of colors and compact structure. All-electric injection molding machine is used in the production of large orders, high precision small and medium-sized parts.

II-How do plastic injection molding machines work ?


The working principle of the injection molding machine is similar to that of the injection syringe. It is a technological process of injecting the plasticized molten plastic (i.e. viscous flow) into the closed cavity by means of the thrust of the screw (or plunger) and obtaining the product after curing.


Injection molding is a cyclic process, each cycle mainly includes:

Quantitative feeding - melting plasticization - pressure injection - cooling - mold opening and taking parts. Remove the plastic parts and then close the mold for the next cycle.


Injection molding machine operation items: injection molding machine operation items include control keyboard operation, electrical control system operation and hydraulic system operation of three aspects. Selection of injection process action, feeding action, injection pressure, injection speed, ejection type, temperature monitoring of each section of the barrel, injection pressure and back pressure adjustment were carried out respectively.


The general molding process of the screw injection molding machine is: first, the granular or powder plastic is added into the barrel, and the plastic is melted by the rotation of the screw and the heating of the barrel outer wall. Then the machine makes the mold and the injection seat move forward, so that the nozzle is close to the gate of the mold, and then the pressure oil is poured into the injection cylinder to make the screw. The rod is pushed forward so that the melt is injected into the closed die with a low temperature at a high pressure and a high speed. After a certain period of time and pressure holding (also known as holding pressure) and cooling, the melt is solidified and molded, and the product can be taken out (the purpose of holding pressure is to prevent the reflux of the melt in the cavity and to supply the material to the cavity. And ensure that the product has certain density and dimensional tolerances. The basic requirements of injection molding are plasticization, injection and molding. Plasticization is the premise to achieve and ensure the quality of the molding products, and in order to meet the molding requirements, injection must ensure sufficient pressure and speed. At the same time, because the injection pressure is very high, corresponding to a high pressure in the cavity (the average pressure in the cavity is generally between 20 and 45 MPa), so there must be sufficient clamping force. It can be seen that the injection device and clamping device are the key parts of the injection molding machine.


The evaluation of plastic products mainly includes three aspects: the first is the appearance quality, including integrity, color, luster, etc; the second is the accuracy between size and relative position; the third is the physical, chemical and electrical properties corresponding to the use. These quality requirements are also different according to the different occasions of the products. The defects of the products mainly lie in the design, precision and wear degree of the mould. But in fact, the technicians in the plastic processing plant often suffer from the difficult situation of using technological means to remedy the problems caused by mold defects and have little effect.


The adjustment of process is the necessary way to improve the quality and output of products. Because the injection cycle itself is very short,

if the process conditions are not well controlled, the waste products will flow continuously. When adjusting the process, it is best to change only one condition at a time and observe it several times. If the pressure, temperature and time are unified and adjusted, it is easy to cause confusion and misunderstanding. There are many ways and means to adjust the process. For example, there are more than ten possible solutions to the problem of unsatisfactory injection of products. Only by choosing one or two main solutions to solve the crux of the problem can we solve the problem. In addition, we should also pay attention to the dialectical relationship in the solution. For example: the product has a depression, sometimes to raise the material temperature, sometimes to reduce the material temperature; sometimes to increase the amount of material, sometimes to reduce the amount of material. Acknowledge the feasibility of solving the problem with reverse measures.

III-The main technical parameters of injection molding machine are


Closing force, maximum injection volume, maximum and minimum die thickness, mold shifting stroke, distance between pull rods, ejection stroke and ejection pressure, etc.

The technical requirements for injection molding machines suitable for molding products can be selected as follows:

1  Clamping force: product projection area multiplied by mold cavity pressure less than clamping force, P is equal to or equal to QF cavity pressure;

2  Maximum injection volume: product weight < maximum injection volume. Product weight = maximum injection volume *75 ~ 85%.

3  Injection molding machine mold thickness: the interval between the maximum and minimum value of the injection molding machine and the two points. Mold maximum thickness injection molding machine less than the maximum mold thickness mold. The minimum thickness is equal to the minimum mold thickness of injection molding machine.

4  Mold stroke: mold opening distance = mold thickness + product height + ejection distance + product space. That is to say, mold-mold distance.

5  The distance between the rods: that is to install the mold position; the mold length * width is less than the pull rod distance.

6  Ejection stroke and pressure: product ejection distance and pressure < ejection stroke and pressure of injection molding machine.


The system and composition of injection machine

Injection molding machine usually consists of injection system, mold closing system, hydraulic transmission system, electrical control system, lubrication system, heating and cooling system, safety monitoring system and so on.


Injection system

Function of injection system: Injection system is one of the most important parts of injection molding machine, generally there are three main forms of plunger, screw, screw pre-plastic plunger injection. The most widely used type is screw. Its function is to inject molten plastic into the mold cavity by screw under certain pressure and speed after plasticizing a certain amount of plastics in a specified time in a cycle of the injection machine. After injection, the melt injected into the mold cavity is kept in shape.

The injection system consists of a plasticizing device and a power transfer device.

The plasticizing device of screw injection molding machine is mainly composed of feeding device, barrel, screw, glue passing component and nozzle. The power transmission device includes an injection cylinder, a moving cylinder of the injection seat and a screw drive device (a


Mold clamping system

The function of clamping system: the function of clamping system is to ensure mold closing, opening and ejecting products. At the same time, after the mold is closed, enough clamping force is supplied to resist the pressure of the mold cavity caused by the melted plastic entering the mold cavity, and the mold seam is prevented, resulting in the bad status of the products.

Composition of the clamping system: the clamping system is mainly composed of clamping device, hanging mechanism, adjusting mechanism, ejecting mechanism, front and rear fixed template, moving template, clamping cylinder and safety protection mechanism.


Hydraulic system

The function of the hydraulic transmission system is to provide power for the injection molding machine according to the various actions required by the process, and to meet the requirements of the pressure, speed and temperature required by the various parts of the injection molding machine. It is mainly composed of various hydraulic components and hydraulic auxiliary components, in which oil pump and motor are the power source of injection molding machine. Various valves control oil pressure and flow rate, so as to meet the requirements of injection molding process.


Electric control system

The reasonable coordination between the electric control system and the hydraulic system can realize the process requirements (pressure, temperature, speed, time) and various program actions of the injection machine. It is mainly composed of electrical appliances, electronic components, instruments (see the bottom right), heaters, sensors and so on. Generally, there are four ways of control, manual, semi-automatic, automatic and adjusted.


Heating / cooling system

The heating system is used to heat the barrel and the injection nozzle. The barrel of the injection molding machine generally uses the electric heating coil as the heating device, which is installed outside the barrel and is subdivided by a thermocouple. Heat supply heat for material plasticization through tube wall heat conduction; cooling system is mainly used to cool oil temperature, too high oil temperature will cause a variety of faults, so oil temperature must be controlled. The other place to be cooled is near the discharge port of the feeding pipe to prevent the raw material from melting at the discharge port, resulting in the raw material can not be fed properly.


Lubrication system

Lubrication system is a circuit which provides lubrication condition for the relative moving parts of injection molding machine, such as moving template, adjusting device, connecting rod hinge and shooting table, in order to reduce energy consumption and improve the life of parts. Lubrication can be either manual lubrication on a regular basis or automatic electric lubrication.


Safety monitoring system

The safety device of injection molding machine is mainly used to protect people and machine safety devices. Mainly by the safety door, safety baffle, hydraulic valve, limit switch, photoelectric detection components and other components, to achieve electrical - Mechanical - hydraulic interlocking protection.

The monitoring system mainly monitors the oil temperature, material temperature, system overload, process and equipment failure of the injection molding machine, and indicates or alarms the abnormal situation.


Mestech equipped 30 sets injection molding machine covering 100 tons to 1500 tons, we can produce plastic product from 0.50 grams to 5 kg of plastic parts of various sizes. If you have plastic products that need injection molding, please contact us

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