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About Injection Molding Machine

Injection molding machine is also known as injection molding machine or injection machine. It is the main molding equipment to make various shapes of plastic products from thermoplastic or thermosetting plastics using plastic molding dies.

Working Principle:

The working principle of the injection molding machine is similar to that of the syringe used for injection, it is with the help of the thrust of the screw (or plunger), the plasticized molten state (i.e., viscous flow state) of the plastic is injected into the closed mold cavity, and then the products are obtained through the process of curing and shaping.

Injection molding is a cyclic process, each cycle mainly includes: dosing – melting and plasticizing – pressure injection – mold cooling – open the mold to take parts. After taking out the plastic parts and then close the mold for the next cycle.

Injection molding machine operation project: injection molding machine operation project includes control keyboard operation, electrical control system operation and hydraulic system operation in three aspects. The injection process action, feeding action, injection pressure, injection speed, ejection type selection, barrel temperature monitoring, injection pressure and back pressure pressure adjustment.

General screw injection molding machine molding process is: first of all, granular or powdered plastic into the barrel, and through the rotation of the screw and the outer wall of the barrel heating so that the plastic becomes molten, and then the machine for the mold and the injection seat forward, so that the nozzle is close to the mold’s gate channel, and then to the injection cylinder through the pressure of the oil, so that the screw forward so that a very high pressure and high speed will be injected into the molten material at a low temperature of the Closed mold, after a certain period of time and pressure to maintain (also known as holding pressure), cooling, so that the solidification of the mold, you can open the mold to take out the product (the purpose of holding pressure is to prevent backflow of the melt in the mold cavity, to the cavity to supplement the material, as well as to ensure that the product has a certain density and dimensional tolerances). The basic requirements of injection molding are plasticization, injection and molding. Plasticization is a prerequisite to achieve and ensure the quality of molded products, and in order to meet the requirements of molding, injection must ensure that there is sufficient pressure and speed. At the same time, due to the high injection pressure, the corresponding high pressure in the mold cavity (the average pressure in the mold cavity is generally between 20 ~ 45MPa), so there must be a large enough clamping force. It can be seen that the injection device and mold closing device are the key components of the injection molding machine.

The evaluation of plastic products has three main aspects, the first is the appearance quality, including integrity, color, gloss, etc.; the second is the accuracy between the size and relative position; the third is the physical properties, chemical properties, electrical properties corresponding to the use. These quality requirements and according to the different occasions of product use, the scale of requirements are different. The defects of the products mainly lie in the design of the mold, manufacturing accuracy and wear and tear. But in fact, the plastic processing plant technicians are often faced with the process means to make up for mold defects brought about by the problem and the results are not very difficult situation.

Adjustment of the production process is to improve the quality of products and production of the necessary way. Because the injection molding cycle itself is very short, if the process conditions are not good, scrap will be endless. When adjusting the process, it is best to change only one condition at a time, and observe a few times, if the pressure, temperature and time are all adjusted together, it is easy to cause confusion and misunderstanding, and do not know what the reason is when something goes wrong. Adjustment process measures, means are various. For example: to solve the problem of product injection is not enough to have more than ten possible solutions, to choose a solution to the crux of the problem of one or two major programs, in order to truly solve the problem. In addition, should also pay attention to the solution of the discursive relationship. For example: the products appear concave, sometimes to increase the material temperature, sometimes to reduce the material temperature; sometimes to increase the amount of material, sometimes to reduce the amount of material. To recognize the feasibility of reverse measures to solve the problem.

Vertical Injection Molding Machine

  1. The injection unit and clamping unit are located on the same vertical centerline, and the mold is opened and closed in the up and down direction. The footprint is only about half that of a horizontal machine, so it is about two times more productive when converted to floor space.
  2. It is easy to realize insert molding. Because the surface of the mold is facing upward, it is easy to put the insert into the positioning. If the lower mold plate is fixed and the upper mold plate is movable, and if the belt conveyor is combined with a robot, fully automatic insert molding can be easily realized.

3、The weight of the mold is supported by the horizontal template for up and down opening and closing action, and the phenomenon that the template cannot be opened and closed due to the forward fall caused by the gravity of the mold similar to the horizontal machine will not occur. It is helpful to keep the precision of machine and mold permanently.

4, through a simple manipulator can take out each plastic part cavity, is conducive to precision molding.

5, general clamping device around the open, easy to configure all kinds of automation devices, adapted to complex, delicate products automatic molding.

6、Pulling the belt conveyor device is easy to realize the string installed in the middle of the mold, easy to realize the molding automatic production.

7、It is easy to ensure the consistency of resin fluidity and mold temperature distribution in the mold.

8、Equipped with rotating table, moving table and tilting table, it is easy to realize insert molding and in-mold combination molding.

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

10, withstood the test of many earthquakes, vertical machine due to the low center of gravity, compared with the horizontal machine seismic resistance is better.

Horizontal injection molding machine

  1. Even for large-sized machines, there is no height restriction for the plant where they are placed due to the low body of the machine.

Corner injection molding machine

2、It is possible to realize automatic molding without the use of robot when the product can be dropped automatically.

3、Due to the low body, it is convenient to supply materials and easy to overhaul.

4、Molds need to be installed by crane.

5、Multi-sets arranged side by side, molded products can be easily collected and packaged by conveyor belt.

Angle Injection Molding Machine

The axis of the injection screw and the axis of movement of the template of the mold clamping mechanism of the corner injection molding machine are arranged perpendicular to each other, and its advantages and disadvantages are between the vertical and horizontal types. Since the injection direction and the parting surface of the mold are in the same plane, the corner injection molding machine is suitable for non-symmetrical geometrical molds with side gates or for products where the molding center does not allow any trace of the gate. As shown in the figure “Angle type injection molding machine”.

Two-color injection molding machine

Can be a one-time injection molding two colors of injection molding machine, can meet the consumer requirements for the appearance, can make the user to use the product more comfortable.

Multi-position molding machine

Its injection device and mold closing device have two or more working positions, or the injection device and mold closing device can be arranged in various ways.

Electric Injection Molding Machine

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

Another advantage of fully electric injection molding machines is the reduction of noise, which not only benefits the workers, but also reduces investment construction costs in soundproof production plants.

Energy saving and consumption reduction

The energy saving of injection molding machine can be divided into two parts: one is the power part and the other is the heating part.

Power part of the energy saving: most of the use of frequency converter, energy saving is through the saving of the motor of the remaining energy consumption, such as the actual power of the motor is 50Hz, and you actually only need 30Hz in production is enough to produce, those excess energy will be wasted, the frequency converter is to change the power output of the motor to achieve the effect of energy saving.

Heating part of the energy-saving: heating part of the energy-saving mostly electromagnetic heaters are used to save energy, the energy saving rate is about 30% -70% of the old resistance circle.

  1. Compared with resistance heating, electromagnetic heaters have more than one layer of insulation, heat utilization increased.
  2. Compared with resistance heating, electromagnetic heaters act directly on the material tube heating, reducing the heat transfer heat loss.
  3. Compared with resistance heating, electromagnetic heater heating speed is faster than a quarter, reducing the heating time.
  4. Compared with resistance heating, electromagnetic heater heating speed, productivity is improved, so that the motor is in a saturated state, so that it reduces the high power low demand caused by power loss.

The above four points are flying as electromagnetic heaters, why can be in the injection molding machine energy saving up to 30% -70% of the reason!

Operating Points

Before starting the machine

  1. Before the operation of the injection molding machine, check whether there is water or oil in the electrical control box, and do not start the machine if the electrical appliances are damp. There should be maintenance personnel to blow dry the electrical parts before starting the machine.
  2. Before the operation of the injection molding machine, check whether the power supply voltage is in line with the general should not exceed ± 6%.

Operation of injection molding machine

  1. Check whether the emergency stop switch, front and rear safety door switches are normal. Verify whether the rotation direction of motor and oil pump is the same.
  2. Check whether the cooling pipes are long distance and smooth, and pass cooling water to the oil cooler and the cooling water jacket at the end of the barrel.
  3. Before the operation of the injection molding machine, check whether there is lubricating oil in each movable part, and add enough lubricating oil.

6.Turn on the electric heat and heat each section of the barrel. When the temperature of each section to meet the requirements, and then hold a period of time in order to stabilize the temperature of the machine. Holding time varies according to the requirements of different equipment and plastic raw materials.

  1. Add enough plastic in the hopper. According to the requirements of injection molding of different plastics, some raw materials are best to be dried first.
  2. Cover the heat shield on the barrel of the machine, which can save electricity and extend the life of the electric heating ring and current contactor [1]. As shown in the figure “Operation of Injection Molding Machine”.

Operation Procedure

  1. Don’t cancel the function of the safety gate at will for the sake of convenience.
  2. Pay attention to the temperature of the pressure oil, the oil temperature should not exceed the specified range. The ideal working temperature of hydraulic oil should be maintained between 45-50 ℃, generally within the range of 35-60 ℃ is more appropriate.
  3. Pay attention to the adjustment of each travel switch to avoid the machine in the action of the impact.

End of work

  1. After the operation of the injection molding machine, the barrel should be cleaned up the plastic, to prevent the leftover material oxidation or long-term thermal decomposition.
  2. The mold should be opened, so that the elbow lever mechanism time in a closed state.
  3. The workshop must be equipped with lifting equipment. When loading and unloading the mold should be very careful to ensure production safety.

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