Injection molding machine is also called injection molding machine or injection machine. It is the main molding equipment that uses plastic molding molds to make plastic products of various shapes from thermoplastics or thermosetting plastics. It is divided into vertical, horizontal and all-electric types. The injection molding machine can heat the plastic, apply high pressure to the molten plastic, and make it eject and fill the mold cavity.

Introduction

Injection molding machine is also known as injection molding machine or injection machine. It is the main molding equipment that uses plastic molding molds to make plastic products of various shapes from thermoplastics or thermosetting materials. Injection molding machines can be divided into vertical, horizontal and vertical-horizontal composite types according to the arrangement of the injection device and the clamping device.

Structure function

composition

The injection molding machine is usually composed of injection system, mold clamping system, hydraulic transmission system, electrical control system, lubrication system, heating and cooling system, safety monitoring system, etc.

Injection system

Function of injection system: injection system is one of the most important components of injection molding machine, generally there are three main types: plunger type, screw type, screw pre-plastic plunger injection type. The most widely used is the screw type. Its function is to heat and plasticize a certain amount of plastic within a specified time in one cycle of the injection molding machine, and then inject the molten plastic into the mold cavity through the screw at a certain pressure and speed. After the injection is completed, the molten material injected into the mold cavity is kept in shape. As shown in Figure 1

Composition of the injection system: The injection system consists of a plasticizing device and a power transmission device.

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

Clamping system

Function of mold clamping system: The function of mold clamping system is to ensure mold closing, opening and ejection of products. At the same time, after the mold is closed, it provides sufficient clamping force to resist the cavity pressure generated by molten plastic entering the cavity, preventing the mold from opening and causing the product to be in poor condition.

Composition of the mold clamping system: The mold clamping system is mainly composed of a mold clamping device, a machine twister, a mold adjustment mechanism, an ejection mechanism, front and rear fixed templates, a movable template, a mold clamping cylinder and a safety protection mechanism.

Hydraulic system

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

Electrical Control

The electrical control system and the hydraulic system are reasonably coordinated to realize the process requirements (pressure, temperature, speed, time) and various program actions of the injection molding machine. It is mainly composed of electrical appliances, electronic components, instruments (as shown in the figure “Instruments”), heaters, sensors, etc. There are generally four control modes: manual, semi-automatic, fully automatic, and adjustment.

Heating/Cooling

The heating system is used to heat the barrel and the injection nozzle. The barrel of the injection molding machine generally uses an electric heating coil as a heating device, which is installed on the outside of the barrel and detected in sections with a thermocouple. The heat is conducted through the barrel wall to provide a heat source for the plasticization of the material; the cooling system is mainly used to cool the oil temperature. Excessive oil temperature will cause a variety of faults, so the oil temperature must be controlled. Another location that needs to be cooled is near the discharge port of the material pipe to prevent the raw material from melting at the discharge port, resulting in the failure of the raw material to be discharged normally.

Lubrication system

The lubrication system is a circuit that provides lubrication conditions for the relatively moving parts of the injection molding machine, such as the moving platen, mold adjustment device, connecting rod hinge, and shooting table, in order to reduce energy consumption and increase the life of parts. Lubrication can be regular manual lubrication or automatic electric lubrication.

Safety Monitoring

The safety device of the injection molding machine is mainly used to protect the safety of people and machines. It is mainly composed of safety doors, safety baffles, hydraulic valves, limit switches, photoelectric detection elements, etc., to achieve electrical-mechanical-hydraulic interlocking protection.

The monitoring system mainly monitors the oil temperature, material temperature, system overload, and process and equipment failures of the injection molding machine, and indicates or alarms when abnormal conditions are found.

Working Principle

The working principle of the injection molding machine is similar to that of a syringe used for injections. It uses the thrust of the screw (or plunger) to inject plasticized molten plastic (i.e., viscous flow state) into a closed mold cavity, and obtains the finished product after solidification and shaping.

Injection molding is a cyclic process, and each cycle mainly includes: quantitative feeding – melting and plasticization – pressure injection – mold filling and cooling – mold opening and taking out the plastic parts. After taking out the plastic parts, the mold is closed again to start the next cycle.

Injection molding machine operation items: Injection molding machine operation items include keyboard operation, electrical control system operation and hydraulic system operation. They are respectively used to perform injection process actions, feeding actions, injection pressure, injection speed, selection of ejection types, monitoring of the temperature of each section of the barrel, and adjustment of injection pressure and back pressure.

The molding process of a general screw injection molding machine is: first, add granular or powdered plastic into the barrel, and make the plastic molten by rotating the screw and heating the outer wall of the barrel. Then the machine closes the mold and moves the injection seat forward, so that the nozzle is close to the gate of the mold. Then, the pressure oil is introduced into the injection cylinder to push the screw forward, so that the molten material is injected into the closed mold with a lower temperature at a very high pressure and a faster speed. After a certain period of time and pressure maintenance (also known as pressure holding), cooling, it is solidified and formed, and then the mold can be opened to take out the product (the purpose of pressure holding is to prevent the backflow of the molten material in the mold cavity, to add materials to the mold cavity, and to ensure that the product has a certain density and dimensional tolerance). The basic requirements of injection molding are plasticization, injection and molding. Plasticization is the premise for achieving and ensuring the quality of molded products, and in order to meet the requirements of molding, injection must ensure sufficient pressure and speed. At the same time, due to the high injection pressure, a high pressure is generated in the mold cavity accordingly (the average pressure in the mold cavity is generally between 20 and 45 MPa), so there must be a sufficiently large clamping force. It can be seen that the injection device and the clamping device are the key components of the injection molding machine.

There are three main aspects to evaluate plastic products. The first is the appearance quality, including integrity, color, gloss, etc. The second is the accuracy of size and relative position; the third is the physical properties, chemical properties, electrical properties, etc. corresponding to the purpose. These quality requirements are different according to the different occasions of product use. The defects of the products mainly lie in the design, manufacturing accuracy and degree of wear of the mold. But in fact, the technicians of plastic processing plants often suffer from the difficult situation of using technological means to make up for the problems caused by mold defects but with little effect.

The adjustment of the process in the production process is a necessary way to improve the quality and output of products. Since the injection molding cycle itself is very short, if the process conditions are not well controlled, there will be endless waste. 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 all adjusted together, it is easy to cause confusion and misunderstanding, and no one knows why there is a problem. There are many measures and means to adjust the process. For example: there are more than ten possible solutions to solve the problem of product filling. Only by selecting one or two main solutions to solve the crux of the problem can the problem be truly solved. In addition, attention should be paid to the dialectical relationship in the solution. For example: if the product is dented, sometimes the material temperature should be increased, sometimes the material temperature should be lowered; sometimes the material amount should be increased, and sometimes the material amount should be reduced. The feasibility of reverse measures to solve the problem should be recognized.

Energy Saving

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

Energy saving in the power part: Most of them use frequency converters. The energy saving method is to save the surplus energy of the motor. For example, the actual power of the motor is 50Hz, but you only need 30Hz in production. The excess energy is wasted. The frequency converter changes the power output of the motor to achieve energy saving.

Energy saving in heating part: Energy saving in heating part mostly adopts electromagnetic heater, and the energy saving rate is about 30%-70% of the old resistance coil.

1. Compared with resistance heating, electromagnetic heater has an extra insulation layer, which increases the utilization rate of thermal energy.

2. Compared with resistance heating, electromagnetic heater directly heats the material tube, reducing heat transfer and heat energy loss.

3. Compared with resistance heating, the heating speed of electromagnetic heater is more than one-quarter faster, which reduces the heating time.

4. Compared with resistance heating, electromagnetic heaters heat faster, which improves production efficiency and keeps the motor in a saturated state, reducing the power loss caused by high power and low demand.

The above four points are the reasons why Feiru electromagnetic heater can save energy up to 30%-70% on injection molding machines.

Classification

(1) Classification by plasticization method

1. Plunger type plastic injection molding machine

Its mixing property is very poor, and its plasticizing property is also not good, and a diverter shuttle device must be installed. It is rarely used.

2. Reciprocating screw plastic injection molding machine;

It relies on a screw for plasticizing and injection, has good mixing and plasticizing properties, and is the most widely used.

3. Screw-plunger plastic injection molding machines rely on screws for plasticization and plungers for injection, and the two processes are separated.

(2) Classification by mold closing method

1. Mechanical

2. Hydraulic

3. Hydraulic – Mechanical

Features

Vertical injection molding machine

1. The injection device and the clamping device are located on the same vertical center line, and the mold is opened and closed in the up and down direction. Its floor area is only about half of that of the horizontal machine, so the productivity is about twice as much when converted into floor area.

2. Easy to achieve insert molding. Because the mold surface is facing upward, it is easy to place the insert in position. If the machine with a fixed lower mold plate and a movable upper mold plate is used, and the belt conveyor device is combined with a robot, fully automatic insert molding can be easily achieved.

3. The weight of the mold is supported by the horizontal template for up and down opening and closing, and the phenomenon of the template being unable to open and close due to the gravity of the mold, like the horizontal machine, will not occur. This is conducive to maintaining the accuracy of the machine and mold for a long time.

4. Each plastic part cavity can be taken out by a simple robot, which is conducive to precision molding.

5. Generally, the surrounding of the clamping device is open, which makes it easy to configure various types of automation devices and is suitable for the automatic molding of complex and delicate products.

6. The belt conveyor device can be easily installed in the middle of the mold, which is convenient for automatic molding 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 inclined table, it is easy to realize insert molding and in-mold combination molding.

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

10. Having withstood the test of many earthquakes, vertical machines have better earthquake resistance than horizontal machines due to their low center of gravity.

Horizontal injection molding machine

1. Even for large machines, there is no height restriction on the factory building where they are installed due to their low body.

2. When the product can fall automatically, automatic forming can be achieved without using a robot.

3. Due to the low machine body, feeding is convenient and maintenance is easy.

4. The mold needs to be installed by crane.

5. When multiple machines are arranged in parallel, the molded products can be easily collected and packaged by the conveyor belt.

Angle injection molding machine

The axis of the injection screw of the angle injection molding machine is perpendicular to the axis of motion of the mold clamping mechanism template. Its advantages and disadvantages are between vertical and horizontal. Because its injection direction and the mold parting surface are on the same plane, the angle injection molding machine is suitable for molds with asymmetric geometric shapes with side gates or products that do not allow gate marks to be left in the molding center.

Two-color injection molding machine

An injection molding machine that can inject two colors at one time can meet consumers’ requirements for appearance and make users feel more comfortable using the product.

Multi-station molding machine

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

Electric injection molding machine

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

Another advantage of all-electric injection molding machines is that they can reduce noise, which not only benefits the workers but also reduces the investment and construction costs in soundproofing production workshops.

Applications

Injection molding machines have the ability to form plastic products with complex shapes, precise dimensions or dense textures with metal inserts in one go. They are widely used in defense, electromechanics, automobiles, transportation, building materials, packaging, agriculture, culture, education, health and people’s daily lives. With the rapid development of the plastics industry, injection molding machines occupy an important position in terms of quantity and variety. Their total production accounts for 20%-30% of the entire plastic molding equipment, making them one of the fastest growing and most produced types of plastic machinery.

Chinese Market

There are many manufacturers of injection molding machines in China, with incomplete statistics showing over 2000. There are two structural forms of injection molding machines: vertical and horizontal. According to the products produced, they can be divided into ordinary and precision injection molding machines.

The robot for injection molding machines is an automated production equipment that can imitate some functions of the upper limbs of the human body and can be automatically controlled to transport products or hold tools for production operations according to predetermined requirements. Chinese plastic processing factories in the coastal areas of South China and East China have shown increasing interest in robots, but the penetration rate of robots for injection molding machines in the chinese plastic machinery industry is less than 10%. Robots can ensure the consistency of the operation cycle, improve quality, and be safer. With the rapid development of the plastic processing industry in China, the degree of automation of injection molding equipment is also getting higher and higher. Modern injection molding machines are often equipped with robots to improve production efficiency. The number of injection molding machines exported and imported by China is basically the same, both about 15,000 units, but the import value is US$920 million and the export value is US$350 million. Precision injection molding machines are mainly foreign brands, and biaxially oriented PET, film units, precision medical catheter extrusion units, etc. in extrusion equipment have always been the territory of foreign companies. It is very necessary to develop domestic precision injection molding and extrusion equipment with independent intellectual property rights. On the one hand, it can replace imports, and on the other hand, it can also enable China to occupy a place in the international high-end plastic machinery market. Traditional plastic machinery still has a certain potential in energy saving, because the previous design often only focused on the production capacity of a single machine. In the design of energy-saving plastic machinery, production speed is no longer the most important indicator, but the energy consumption per unit weight of the product. Therefore, the mechanical structure, control mode, and operating process conditions of the equipment must be optimized based on the minimum energy consumption.

As energy conservation and consumption reduction has become a national strategy, the energy conservation of injection molding machines has also received widespread attention. In the field of conventional injection molding machines, there are two relatively mature ways of energy conservation in motors: frequency converters and servo motors, among which servo motors are becoming more and more widely accepted.

The servo energy-saving series injection molding machines are equipped with a high-performance servo variable speed power control system. During the molding process of the injection molding machine, different frequency outputs are made for different pressure flows, and precise closed-loop control of the pressure flow is performed to achieve high-speed response, optimal matching and automatic adjustment of the servo motor to the energy requirements of the injection molding machine.

1. Use energy-saving devices such as servo controller and servo motor with excellent performance.

2. Sensitive servo control system, quick start response time only 0.04S.

3. The servo motor and hydraulic system form a closed-loop control, which greatly improves the repeatability accuracy compared to traditional models.

4. Reduce the impact of opening and locking the mold, and extend the service life of mechanical parts and molds.

5. Reduce electricity usage. Under ideal working conditions, this machine can save 20% to 80% of electricity compared to traditional injection molding machines.

6. The system heat generation is much lower than that of traditional injection molding machines, saving about 30% of cooling water and extending the service life of oil circuit seals and hydraulic parts.

7. The whole line has low noise during operation, which is significantly lower than that of traditional injection molding machines.

Operation Points

Before starting

1. Before operating the injection molding machine, check whether there is water or oil in the electrical control box. If the electrical appliance is damp, do not start the machine. Maintenance personnel should blow dry the electrical parts before starting the machine.

2. Before operating the injection molding machine, check whether the power supply voltage is in compliance with the regulations. Generally, it should not exceed ±6%.

3. Check the emergency stop switch and the front and rear safety door switches to see if they are normal. Verify that the motor and oil pump are rotating in the same direction.

4. Check whether all cooling pipes are unobstructed and supply cooling water to the cooling water jackets at the oil cooler and barrel end.

5. Before operating the injection molding machine, check whether there is lubricating oil in each moving part and add enough lubricating oil.

6. Turn on the electric heating to heat each section of the barrel. When the temperature of each section reaches the required level, keep it warm for a while to stabilize the machine temperature. The insulation time varies according to the requirements of different equipment and plastic raw materials.

7. Add enough plastic into the hopper. According to the requirements of different plastics for injection molding, some raw materials are best dried first.

8. Cover the heat shield on the barrel to save energy and extend the life of the heating coil and contactor. As shown in the figure “Operation of injection molding machine”.

Operation process

1. Do not cancel the function of the safety door for the sake of convenience.

2. Pay attention to the temperature of the pressure oil, and do not let the oil temperature exceed the specified range. The ideal operating temperature of the hydraulic oil should be maintained between 45-50℃, and is generally more suitable within the range of 35-60℃.

3. Pay attention to adjusting the travel switches to avoid collision when the machine is in motion.

End of work

1. After the injection molding machine is operated, the plastic in the barrel should be cleaned to prevent the residual material from oxidation or long-term thermal decomposition.

2. The mold should be opened so that the toggle mechanism is always in the locked state.

3. The workshop must be equipped with lifting equipment. Be very careful when installing and disassembling molds to ensure production safety.

Precautions

Hazard

There are five major hazards of excessive temperature rise in injection molding machines : thermal deformation of the machine, reduced oil viscosity, deformation of rubber seals, accelerated oxidation and deterioration of the oil, and also reduced air pressure.

Hazard 1: Thermal deformation of machinery

Moving parts with different thermal expansion coefficients in hydraulic components get stuck due to the reduction of their matching clearance, causing malfunction, affecting the transmission accuracy of the hydraulic system, and resulting in poor working quality of the parts.

Hazard 2: Reduce the viscosity of the oil

Excessive temperature rise of the injection molding machine will lead to a decrease in oil viscosity, increased leakage, and a significant decrease in the volumetric efficiency of the pump and the efficiency of the entire system. As the viscosity of the oil decreases, the oil film of moving parts such as the slide valve becomes thinner and cut, the friction resistance increases, and the wear is aggravated.

Hazard 3: Deformation of rubber seals

Excessive temperature rise of the injection molding machine will cause the rubber seal to deform, accelerate aging and failure, reduce sealing performance and service life, and cause leakage.

Hazard 4: Accelerates oil oxidation and deterioration

Excessive temperature rise of the injection molding machine will accelerate the oxidation and deterioration of the oil, precipitate asphalt substances, and reduce the service life of the hydraulic oil. The precipitates block the damping holes and the slit valve ports, causing the pressure valve to be stuck and unable to move, the metal pipeline to stretch and bend, or even rupture.

Hazard 5: Deterioration of component quality

If the temperature of the injection molding machine is too high, the working quality of the parts will deteriorate, the dissolved air in the oil will escape, cavitation will occur, and the working performance of the hydraulic system will be reduced. The ideal working temperature of the hydraulic system should be between 45 degrees and 50 degrees. The reason is that the hydraulic system is designed based on a selected pressure oil viscosity, but the viscosity will change with the oil temperature, which will affect the working components in the system, such as cylinders, hydraulic valves, etc., and reduce the control accuracy and response sensitivity, especially for precision injection machines. At the same time, too high a temperature will accelerate the aging of the seals, causing them to harden and break; if the temperature is too low, the processing energy consumption will be large, which will reduce the operating speed. Therefore, it is necessary to pay close attention to the working temperature of the hydraulic oil. There are many reasons for the high oil temperature, but most of them are attributed to oil circuit failure or failure of the cooling system.

Approach

(1) According to different load requirements, regularly check and adjust the pressure of the relief valve to make it just right.

(2) Choose hydraulic oil reasonably, especially the oil viscosity. If conditions permit, try to use a lower viscosity to reduce viscosity friction loss.

(3) Improve the lubrication conditions of moving parts to reduce friction losses, which is beneficial to reducing workload and heat generation.

(4) Improve the assembly quality and precision of hydraulic components and hydraulic systems, strictly control the clearance of matching parts and improve lubrication conditions. Use sealing materials with low friction coefficients and improve sealing structures to reduce the starting force of the hydraulic cylinder as much as possible to reduce the heat generated by mechanical friction losses.

(5) Install cooling equipment when necessary.

Selection

Generally speaking, customers who have been engaged in the injection molding industry for many years are mostly able to judge and choose the appropriate injection molding machine for production. However, in some cases, customers may need the assistance of the manufacturer to decide which specification of injection molding machine to use. Customers may even only have product samples or ideas, and then ask the manufacturer whether the machine can produce it, or which model is more suitable.

In addition, some special products may need to be equipped with special devices such as accumulators, closed circuits, injection compression, etc. to be produced more efficiently. Therefore, how to determine the appropriate injection molding machine for production is an extremely important issue. The following information is provided for readers’ reference.

The important factors that usually affect the selection of injection molding machines include molds, products, plastics, molding requirements, etc. Therefore, the following information must be collected or available before making a selection:

Mold dimensions (width, height, thickness), weight, special designs, etc.

Type and quantity of plastics used (single raw material or multiple plastics);

The appearance dimensions (length, width, height, thickness) and weight of the finished injection molded product; molding requirements, such as quality conditions and production speed.

After obtaining the above information, you can follow the steps below to select the appropriate injection molding machine:

1. Choose the right model: The model and series are determined by the product and plastic.

Since there are many types of injection molding machines, you must first correctly determine which type of injection molding machine or which series should be used to produce this product, such as general thermoplastic plastics, bakelite materials, or PET materials, and whether it is single color, two colors, multiple colors, sandwich or mixed colors. In addition, some products require high stability (closed loop), high precision, ultra-high injection speed, high injection pressure or fast production (multi-loop) and other conditions, and you must also choose the appropriate series to produce.

2. Can it fit: Determine whether the “large column inner distance”, “mold thickness”, “minimum mold size” and “mold plate size” of the machine are appropriate based on the mold size to confirm whether the mold can fit.

The width and height of the mold must be smaller than or at least one side must be smaller than the inner distance of the large column;

The width and height of the mold should preferably be within the mold plate size range;

The thickness of the mold needs to be between the mold thickness of the injection molding machine;

The width and height of the mold must meet the minimum mold size recommended by the injection molding machine. It cannot be too small.

3. Take out: Determine whether the “mold opening stroke” and “mold ejection stroke” are sufficient to take out the finished product based on the mold and the finished product.

The mold opening stroke must be at least twice the height of the finished product in the mold opening and closing direction, and must include the length of the vertical sprue;

The ejector stroke must be sufficient to eject the finished product;

4. Locking: The tonnage of “locking force” is determined by the product and plastic.

When the raw material is injected into the mold cavity at high pressure, a force will be generated to support the mold. Therefore, the clamping unit of the injection molding machine must provide sufficient “clamping force” to prevent the mold from being stretched open. The calculation of the clamping force requirement is as follows:

Calculate the projected area of ​​the finished product in the direction of the opening and closing mold from the finished product’s appearance dimensions;

Mold support force = projected area of ​​finished product in the direction of mold opening and closing (cm2) × number of mold cavities × mold pressure (kg/cm2);

The pressure in the mold varies with the raw material, generally 350-400kg/cm2;

The clamping force of the machine must be greater than the supporting force, and for safety reasons, the clamping force of the machine usually needs to be greater than 1.17 times the supporting force;

At this point, the specifications of the clamping unit have been preliminarily determined, and the tonnage of the machine has been roughly determined. Next, the following steps must be performed to confirm which injection unit has a screw diameter that best meets the requirements.

5. Full shot: Determine the required “shot volume” based on the finished product weight and the number of cavities and select the appropriate “screw diameter”.

The number of cavities in the mold (how many cavities in one mold) must be considered when calculating the weight of the finished product.

For the sake of stability, the injection volume must be more than 1.35 times the weight of the finished product, that is, the weight of the finished product must be within 75% of the injection volume;

6. Good injection: The plastic determines the “screw compression ratio” and “injection pressure” and other conditions. Some engineering plastics require higher injection pressure and appropriate screw compression ratio design to achieve better molding effects. Therefore, in order to make the finished product better, the injection pressure requirements and compression ratio issues must also be considered when selecting the screw.

Generally speaking, a screw with a smaller diameter can provide a higher injection pressure.

7. Shoot fast: and confirm the “shooting speed”.

Some finished products require high injection rate and high injection speed to form stably, such as ultra-thin finished products. In this case, you may need to confirm whether the injection rate and injection speed of the machine are sufficient, and whether it needs to be equipped with accumulators, closed-loop control and other devices. Generally speaking, under the same conditions, screws that can provide higher injection pressures usually have lower injection speeds, and conversely, screws that can provide lower injection pressures usually have higher injection speeds. Therefore, when selecting the screw diameter, the injection volume, injection pressure and injection rate (injection speed) need to be cross-considered and traded off.

In addition, a multi-circuit design can also be used to shorten the molding time by synchronous compound actions.

After the above steps, in principle, you can decide on the injection molding machine that meets your needs, but there are some special issues that may also need to be considered, including:

Size matching problem:

In some special cases, the customer’s mold or product may have a small mold size but a large injection volume, or a large mold size but a small injection volume. In this case, the standard specifications pre-set by the manufacturer may not meet the customer’s needs, and the so-called “size matching” must be carried out, that is, “large wall and small injection” or “small wall and large injection”. The so-called “large wall and small injection” refers to the original standard clamping unit with a smaller injection screw, and conversely, “small wall and large injection” means the original standard clamping unit with a larger injection screw. Of course, the clamping and injection may differ by several levels in matching.

The concept of fast machine or high-speed machine:

In actual use, more and more customers will ask to buy so-called “high-speed machines” or “fast machines”. Generally speaking, in addition to the needs of the product itself, the purpose is mostly to shorten the molding cycle, increase the output per unit time, and thus reduce production costs and improve competitiveness. Usually, there are several ways to achieve the above goals:

Speed ​​up the injection speed: increase the size of the motor and pump, or add an accumulator (preferably with closed-loop control);

Increase the feeding speed: increase the size of the motor and pump, or reduce the size of the feeding hydraulic motor to increase the screw speed;

Multi-circuit system: adopts dual-circuit or triple-circuit design to perform compound actions synchronously and shorten molding time;

Add mold water channels to improve mold cooling efficiency;

However, there is no such thing as a free lunch. Improving and modifying machine performance can certainly increase production efficiency, but it often also increases investment and operating costs. Therefore, the benefit assessment before investment must be carefully weighed in order to use the most appropriate machine model to generate the highest benefits.

Purchase points

Injection molding machine is a common plastic machinery. For operators who use and purchase injection molding machines, they should first understand the performance of a good injection molding machine and what aspects need to be evaluated before they can choose a satisfactory injection molding machine. Let’s learn what aspects should be paid attention to when purchasing an injection molding machine.

When purchasing an injection molding machine, the technical parameters of the injection molding machine. When purchasing an injection molding machine, users can make a judgment through vertical or horizontal comparison. The so-called “vertical” means that the main technical parameters of the injection molding machine should meet the industry standards and be examined according to the industry standards. The so-called “horizontal” is to compare the technical parameters of similar injection molding machines. Therefore, this is a very careful and scientific work. The parameters of the injection molding machine at all levels should be selected according to the material, shape, structure and even application field and specific occasion of the injection molded product; according to the structure, quality, precision, number of cavities, type of flow channel and its structure, shape and size; according to the degree of automation of the daily, monthly and annual production capacity of the product.

When choosing a supplier for an injection molding machine, it is best to choose a manufacturer with a service center nearby, because the structure of the injection molding machine is complex and problems are inevitable. Fast after-sales service is critical. When purchasing, do not blindly seek low prices. The prices of domestic and imported parts on the injection molding machine are very different, so you need to try to figure out what brand of parts the manufacturer uses. Of course, you cannot see some parts, such as oil seals, bearings, etc., so the manufacturer’s reputation and credibility are critical at this time.

When choosing a model of an injection molding machine, the two main parameters of the injection molding machine are the injection volume and the clamping force. To ensure the quality of the processed product, the actual weight of the product in one mold should be within 70% of the theoretical injection volume of the machine. The required clamping force should be calculated based on the projected area of ​​the product. Special attention should be paid to whether the machine’s column distance, mold opening stroke, and minimum mold thickness are suitable for the mold.

The man-machine dialogue ability and operability of the injection molding machine should be selected. The injection molding machine should make its operation and management more humanized, the operation should be convenient, and the display should be clear, easy to understand, and clear at a glance. It has the functions of parameter selection, product quality control, mold data storage and automatic reproduction of various parameters, which can quickly diagnose and eliminate faults, reduce material waste in the shortest time, and restore the normal operation of the system. The key points of purchasing injection molding machines are the stability, reliability, safety and service life of the machine. The stability of the machine is mostly reflected in whether the clamping mechanism and the injection molding system run smoothly in each cycle, work in silence without impact, and the noise shall not exceed the industry standard. These situations are related to the manufacturing and assembly accuracy of the machinery, and are also related to the reasonable design and structure of the toggle connecting rod. Reliability and service life are mainly reflected in the system rigidity of the mold clamping mechanism, which is related to the structure, size, material and heat treatment process of the template, tie rod, connecting rod and its pin shaft; the plastic system of the injection molding machine, such as the barrel, screw, screw head, check ring and the structure and manufacturing process of the screw drive spindle, are the main force-bearing parts and wear parts of the injection molding machine, which directly affect the service life. The safety of the injection molding machine is very important. When the mold clamping mechanism opens and closes the mold, the reliability of the low-voltage protection system involves human-machine safety. Modern injection molding machines require the implementation of a joint safety protection system of electrical, mechanical and hydraulic systems. This protection mainly reflects two aspects: one is the safety protection of the mold, and the other is the safety protection of the person. Before closing the mold, when the safety door is not closed, the mold should not be able to move; during the mold closing process, if the safety door is not closed to the correct position, the template will stop moving or automatically open the mold. If foreign matter, such as inserts, falls into the cavity by mistake due to vibration when the mold is closed, or other foreign matter, such as hands, is mistakenly placed in the mold, the mold should stop closing, or automatically open the mold and alarm.

Another safety aspect of the injection molding machine is to prevent the pre-molding screw from cold start. When the material in the screw does not reach the specified temperature and insulation time, it is forbidden to start, otherwise an alarm will be triggered. A protective device for the injection molding machine nozzle splash is necessary to prevent burns.

The key points of purchasing an injection molding machine are that the degree of automation should be high, the functions should be complete and perfect, and the production efficiency should be high. Modern injection molding machines can realize manual, semi-automatic, and fully automatic operation. As long as the mold design is reasonable, it can realize fully automatic operation from injection molding to product ejection and falling. It can also be equipped with a manipulator to realize unmanned operation. The core extraction and insertion function, hydraulic nozzle control function, and rapid heating flow channel probe function can all be incorporated into the automatic program of the injection molding cycle for automatic circulation. The high production efficiency is mainly reflected in the short molding cycle of each molded product under normal injection molding process conditions. This is a comprehensive performance indicator of the mechanical, electrical, and hydraulic systems of an injection molding machine. Therefore, high-quality hydraulic and electronic components must be used, and precise manufacturing technology must be used to improve the sensitivity and various repetitive accuracy of the injection molding machine system. This is a reliable guarantee for the efficient operation of the injection molding system.

Energy saving and environmental protection are the key points for choosing and purchasing injection molding machines. They are indicators that cannot be ignored in judging modern injection molding machines. Energy saving mainly reflects the ability of the injection molding machine to save water and electricity when compared with similar machines under normal process conditions in the heating system ( electromagnetic heating ), power drive system (inverter, servo, etc.), and heat dissipation system. The design of modern injection molding machines should fully consider the theme of “environmental protection”. Injection molding machines should prevent hydraulic oil leakage or excessive noise and work quietly. In addition, the injection molding machine itself should also use more environmentally friendly materials.

The key point of purchasing an injection molding machine is that the machine maintenance and overhaul should be convenient. The installation location of various machines such as mechanical, hydraulic, electronic, and electrical components should be conducive to the maintenance and overhaul of the machine. At the same time, the universality and standardization of the injection molding machine are also very important to users.

Safety

1.1 General safety rules

The maintenance, repair and servicing of the machine must be performed by experts who are sufficiently qualified and have extensive experience in the field of injection molding machines. They should be familiar with industrial life and safety standards and should be familiar with the construction and function of the necessary machine safety equipment.

Notice:

The purpose of the safety device installed on the machine is to protect the operator’s life safety and ensure that the product is not damaged.

The machine can only be operated when all safety devices are in normal working condition.

No safety device may be removed at will.

Security facilities also include programs in the software, and no modification of the programs is allowed.

If any accident or error occurs in the safety device, the machine must be shut down immediately;

Emergency stop button. Turn off the cooling water supply after about 20 minutes. The person in charge must be notified immediately.

Before restarting the machine, the fault must be eliminated.

1.1.1 Machine safety labels

During production, please pay attention to the safety signs, use Chinese and English, and always adhere to the principle of “safety first”.

1.1.2 Precautions during maintenance

Notice:

All maintenance work must be carried out when the main power switch of the injection molding machine is set to “0” and locked with a padlock if necessary.

Employers have the responsibility to inform operators about the construction and function of safety facilities and to take personal health and safety seriously.

Notice:

Any work that would damage the machine’s safety features should be stopped.

Employers must ensure that operators are experienced and qualified operators.

In any case, the safety devices should not be removed from the machine or become inoperative. If it is necessary to remove the safety device to repair the machine, it must be safe. After the repair work is completed, reinstall the safety device as it was and check the effect.

Any changes to safety facilities are not allowed without permission!

1.1.3 Removal of toxic fumes

Some plastics emit toxic fumes when overheated, primarily polytetrafluoroethylene (PTEE), polyoxymethylene (POM), and polyvinyl chloride (PVC).

If these toxic fumes cannot be removed by emergency mechanical devices, it is recommended to install an exhaust fan to remove the harmful fumes, and the exhaust fan switch is required to be interlocked with the injection molding machine power switch.

Notice:

If the fume extractor is mounted directly on the machine, we recommend mounting it on the fixed platen.

1.1.4 Prevention of plastic decomposition

When heated for a long time, some plastics will decompose and explode. These plastics are mainly polyoxymethylene (POM) and polyvinyl chloride (PVC).

When processing this type of plastic, be careful to move the nozzle away from the mold when the injection pressure increases so that the decomposition gas can escape from the nozzle.

Accident prevention is achieved through the following measures:

Strictly set the process and parameters according to the material characteristics of the plastic, especially the heating temperature and residence time in the barrel. When processing heat-sensitive plastics, the residence time of the plastic in the barrel should be shortened. When production is interrupted or the material is degraded, it should be cleaned with polyethylene (PE) (using the barrel of the heat-sensitive plastic) and then stopped heating.

1.1.5 Prevent accidents caused by over-prefabrication

Generally, it is more appropriate to set the pre-plasticizing amount to be about 15% of the product weight. If the pre-plasticizing amount is too large, there will still be too much high-temperature and high-pressure molten material left in the barrel and hot runner after injection molding; if the pre-plasticizing back pressure is too high, when the pre-plasticizing is completed, there will still be a high residual pressure of the molten material in the barrel. When manually cleaning the mold cavity or repairing the mold, this energy may be suddenly released and the high-temperature material may injure people. For this reason, the injection seat must be retreated in advance to make the nozzle leave the mold mouth, and the oil pump motor must be stopped after the mold is opened.

1.2 Safety equipment

1.2.1 General equipment

Safety facilities include protective devices and insurance mechanisms

The protective door can prevent anyone or anything from entering the danger zone and protect people from being hurt by the splash of molten plastic. When the protective door is opened, the safety mechanism will interrupt any dangerous mechanical movement. The outer dimensions of the mold area mobile protective door and the hydraulic ejection mechanism are designed to have a sufficiently large safety edge. For larger molds, the size of the protective door is increased accordingly.

1.2.2 Safety devices

1. Movable protective door in mold area – operating side/counter-operating side
2. Nozzle guard
3. Injection device fixed protective cover – operation method
4. Fixed protective door of clamping system – operating side / counter-operating side
5. Fixed protective door for clamping system – side
6. Hydraulic safety door
7. Mechanical safety device
8. Electrical safety device
9. Barrel electric heating shield
10. Top protective cover plate

1.2.3 Movable protective door in mold area

There are three safety brake mechanisms for the moving door insurance in the mold cavity area, one is the mechanical safety brake device, the second is the hydraulic safety brake device (except PD60-PD148), and the third is the electrical safety brake device.

When the protective door is opened, the three safety mechanisms automatically work to prevent the clamping device, demoulding system and injection device from moving. When the electrical safety of the injection molding machine works, the main motor does not work.

The mechanical safety device moves the mechanical safety bumper to make the mechanical safety stopper fall, thereby preventing the movement of the mechanical safety rod and preventing the mold closing action.

The electrical fuse stops all mold closing actions in the electrical system through the action of the safety travel switch.

Error message:

If the machine is started without the protective door closed, the screen will display the message “Safety door not closed” in case of erroneous operation:

Error message elimination:

Close the protective safety door. If the information on the display screen is still not cancelled, continue to check the travel switch, adjust or repair the travel switch; after the error is eliminated, the error message will be automatically cancelled.

1.2.4 Nozzle protective cover

In order to prevent the hot plastic from spraying out and injuring people, a metal nozzle protective cover is set at the working position of the nozzle, a movable door cover with an observation window is installed on the protective cover, and a safety travel switch is installed on the movable door cover.

When the nozzle guard is opened, “injection seat forward”, “injection” and “pre-molding” will all stop (some series of models may be slightly different due to configuration).

Semi-automatic and fully automatic operation cancelled.

Error message:

If the nozzle protection cover is not closed when starting, the display will show “Nozzle protection cover is not closed”. After closing the protection cover, the error message disappears and you can resume working.

1.2.5 Hopper filling

During operation, the auxiliary feeding equipment shall be provided by the user and must be fixed to the feeding port. Auxiliary facilities such as ladders, platforms or feeders should be used to feed materials into the hopper.

Attention! It is forbidden to step on the injection molding device to perform maintenance or step on the machine body to add materials to the hopper. Such operation may cause injury.

1.2.6 Fixed protective door

The fixed protective door is tightened with screws and can only be opened with appropriate tools. It can only be removed during maintenance.

Attention! It is not permitted to operate the machine with the fixed protective door open.

Fixed protective doors are installed on the operation side and the anti-operation side of the mold clamping area, in front of and on the side of the injection device. Other fixed protective doors prevent the mold clamping device from entering from the second plate side: to prevent the barrel insulation device from being hit.

Attention! PPE protective gloves and safety glasses must be worn when working in the plasticizing and injection area; the oil pump system safety valve is not allowed to be adjusted under any circumstances.

1.2.7 Other hazards caused by opening the nozzle guard

If the hopper is removed or filling is interrupted, the increased heat in the barrel means there is a fire hazard at the filling port.

Fires can also occur in the nozzle area because the nozzle is hot and has a heating ring while the melt is spraying out.

1.3 Hydraulic safety device

The hydraulic safety system is mainly realized by the system safety valve in addition to the hydraulic protection safety valve of the protective door. The manufacturer has set the maximum allowable value and closed it. If the pressure value exceeds the set value, the system safety valve will open.

The safety valve reduces the pressure in the hydraulic system and protects the operator, preventing the hose and steel pipe connections from being damaged by excessive pressure. It also protects against damage caused by errors in the hydraulic system. The safety valve protects the oil pump in the hydraulic drive unit from overload.

Note! Under no circumstances is it allowed to adjust the oil pump system safety valve.

1.4 Electrical safety devices

Electrical safety devices include basic grounding wire and emergency stop button.

All electrical parts of the machine have grounding wires, especially the electric heating part, the heating coil must be lifted up for inspection.

The emergency brake buttons are respectively arranged on the operation panel and the protective plate of the head plate.

If this button is pressed, all machine movements will stop immediately, including the oil pump motor. All operating devices connected to the standard interface will also be turned off.

For safety reasons, once the emergency brake button is pressed, the machine will stop immediately.

Rotate the outer ring of the button to a certain angle, and the button will reset. Then the operation will restart and the error will disappear.

The circuit breaker has a voltage loss protection function.

1.5 Check safety equipment

Attention! When the customer tests the machine after installing it, he should first check whether the safety devices are effective. If there is an error in the safety device, the machine should be stopped immediately.

When the machine is returned to working order, the cause of the error must be found and eliminated.

We recommend the following inspection methods for safety facilities:

During the machine test, the operator and the installer must jointly check and carefully check the moving parts of the machine to see if there are any foreign objects that may hinder the operation of the machine. After confirmation, close the movable protective door. Use the manual mold opening button to move the template to the left to the mold opening position. Open the movable protective door and visually check whether the mechanical safety block falls to prevent the mold closing action. Press the mold closing button in time, and there should be no mold closing action. If there is any action, check and adjust the hydraulic safety switch. Press the demoulding button, plasticizing button, injection button, and grounding button in time. If there is any action, check and readjust the electrical safety switch. Close the movable protective door, and the safety collision block will lift the mechanical safety block and press down the electrical safety switch, while causing the hydraulic safety switch to pop up. At this time, all button controls on the operating panel are valid. Inspection of safety devices includes the following items:

The rigidity of the actuator; whether the safety insurance mechanism is fastened to the machine; whether all wires are properly connected to the electrical safety switch; whether each individual safety device and limit switch functions normally. Note! When the protective door is open during the safety inspection, the dangerous part of the machine is exposed. Make sure your body and other objects are away from this area.

Check the travel switch of the nozzle guard and wear protective glasses to prevent molten material from splashing and causing harm.

If a fault is detected in the safety device, the machine must be switched off immediately! Before restarting the machine, the fault and its cause must be eliminated.

Fault

1. According to the fault status, it can be divided into:

(1) Gradual failure. This is caused by the gradual deterioration of the initial performance of the injection molding machine. Most of the failures of injection molding machines belong to this type of failure. This type of failure is closely related to the wear, corrosion, fatigue and creep of electronic control and hydraulic mechanical components.

(2) Sudden failure. It is caused by the combined effect of various unfavorable factors and accidental external influences, which exceed the limit that the injection molding machine can withstand. For example: the screw breaks due to overload caused by iron entering the barrel; the electronic board of the injection molding machine is broken due to high voltage series. This type of failure often occurs suddenly without any signs in advance.

Sudden failures often occur during the use of injection molding machines, often due to defects in design, manufacturing, assembly and materials, or operating errors and illegal operations.

2. According to the nature of the fault, it can be divided into:

(1) Intermittent failure. The injection molding machine loses some of its functions in a short period of time, which can be restored with a little repair and debugging, without the need to replace parts.

(2) Permanent failure. Some parts of the injection molding machine are damaged and need to be replaced or repaired before they can be put back into use.

3. According to the degree of fault impact, it can be divided into:

(1) Complete failure. The injection molding machine loses its function completely.

(2) Local failure. This causes the injection molding machine to lose some functions.

4. According to the cause of the failure, it can be divided into:

(1) Wear failure: Failure caused by normal wear of the injection molding machine.

(2) Misuse failure: Failure caused by incorrect operation or improper maintenance.

(3) Inherent weakness failure: Due to design problems, the injection molding machine has weak links, which cause failures during normal use.

5. According to the danger of the fault, it can be divided into:

(1) Dangerous failures. For example, the safety protection system loses its protective function due to a fault when it needs to act, causing personal injury and injection molding machine failure; failure caused by failure of the hydraulic electronic control system, etc.

(2) Safety failures. For example, the safety protection system is activated when it is not required; the injection molding machine is started when it cannot be started.

6. According to the occurrence and development rules of injection molding machine failures, they can be divided into;

(1) Random failure: The time when the failure occurs is random.

(2) Regular failures. Failures occur in a certain pattern.

Each fault has its main characteristics, namely the so-called fault mode or fault state. The fault states of various injection molding machines are quite complicated, but they can be summarized into the following types: abnormal vibration, mechanical wear, input signal cannot be accepted by the computer, solenoid valve has no output signal, mechanical hydraulic component rupture, proportional linear imbalance, hydraulic pressure drop, hydraulic leakage, oil pump failure, hydraulic noise, circuit aging, abnormal sound, oil quality deterioration, power supply voltage drop, amplifier board no output, temperature out of control and others. The proportion of various fault modes of different types of injection molding machines is different.

Special Machine

The mold temperature controller for injection molding is a peripheral device of the injection molding machine, which is used to control the mold temperature. The working temperature is up to 180℃. It adopts the most advanced process design in the world today, with high temperature control accuracy, fast heat conduction speed, high efficiency and energy saving. It can also be equipped with functions such as automatic suction and return water, full negative pressure operation, RS485 communication, etc. The mold temperature controller for injection molding has been widely used in various injection molding companies.

Repair And Maintenance

1. Check whether the running mold is in normal condition: whether there is low-pressure mold locking protection; whether the active parts such as guide pillars, ejector rods, and slides are worn, and whether the lubrication is good? It is required to add oil at least once every 12 hours, and the number of oiling times for special structures should be increased. Whether the screws and clamps of the mold’s fixed template are loose; normal production conditions: check whether the product defects are related to the mold; when the machine is removed, the mold must be fully inspected and rust-proofed: wipe dry the cavity, core, ejector mechanism, slide and other parts and spray the mold with mold rust inhibitor or apply butter.

After the mold is removed from the machine, it should be placed in a designated place and records should be made: (1) Mold condition: intact or to be repaired. (2) Rust-proof treatment method when the mold is removed.

2. Quarterly routine inspection: mainly to clean and maintain molds that have not been used for more than two months.

2.1 Open the mold and check the internal anti-rust effect. If there is any abnormality, the anti-rust treatment must be carried out again. Moulds that are not used for a long time must be coated with butter.

2.2 Put it back in place and make a record.

3. Maintenance precautions:

(1) Non-professional maintenance personnel or without the permission of professional maintenance personnel are not allowed to dismantle the mold for maintenance.

(2) If there are minor faults during the production process, the machine adjustment personnel can solve them according to the situation. For example: 2.1 The mold is stuck to the inlet: Use a copper needle to knock it out at the inlet. Do not use hard objects such as steel needles to knock the mold. 2.2 If there are slight mold marks in the cavity, you can choose polishing materials according to the finish of the cavity. Do not use sandpaper or other polishing materials on the textured surface. Generally, use a copper brush dipped in diamond paste or diamond mortar to brush it, and it should be completed by professional maintenance personnel. 2.3 Product sticking to the mold: Generally, use hot plastic to cover the product and the ejection part, and eject it after cooling. If you use fire, be careful not to damage the mold surface.

(3) When professionals repair the mold, they cannot change the structure at will. If the structure needs to be changed, it must be approved by the quality engineering department.

(4) Ensure the quality of maintenance, select appropriate equipment, materials, tools and problem-solving methods, and complete them as quickly as possible.

4. Quality records:

1. Purpose: To standardize the use and maintenance of plastic injection molds, reduce mold damage, and ensure that product quality meets customer needs.

2. Responsibilities: This standard must be implemented and inspected by qualified injection molding technicians. 2.2 The injection molding foreman is responsible for implementation and inspection supervision, and the supervisor shall supervise regularly.

Prospects

Looking back at the total global export of injection molding machines in 2008, the total export volume was US$5.46 billion. Germany’s injection molding machine industry ranked first in the world, with total exports accounting for more than 20% of the world’s total exports, and it is in a dominant position in the global competition for injection molding machines. Italy and Japan ranked second and third respectively. The export share of injection molding machines in the United States has been declining year by year, from 9.8% in 2000 to 5.3% in 2008. Japan’s electric injection molding machines occupy an important position in the world, and the share of electric injection molding machines in North America has reached about 30%. The injection molding machines in Europe, the United States and Japan are mainly high-tech and high-value-added models such as precision injection molding machines and large injection molding machines. After years of technology introduction and technological innovation, the manufacturing level of China’s plastic machinery industry in the field of low-end injection molding machines is almost the same as that of developed countries. Coupled with the advantage of labor prices, China’s low-end injection molding machine exports occupy half of the world. In addition, China’s plastic machinery industry has not only made great progress in the field of mid-range injection molding machines, but also achieved important breakthroughs in the field of high-end injection molding machines. The market share of China’s plastic machinery is expected to gradually expand.

In terms of the global market structure, the continued development of the global construction market will drive the demand for extruded products such as plastic pipes and sidings, and in turn drive the demand for extrusion equipment. Therefore, it is expected that the global demand for extrusion equipment will exceed that of other types of plastic machinery products. According to a survey by the US Industrial Market Research Company, the demand for plastic machinery in the United States and Japan will show signs of recovery again, and the demand in the Western European market will accelerate in 2009. The sales prospects of plastic machinery in China, India and Russia are promising. The demand for plastic machinery in Turkey, the Czech Republic, Iran and other developing countries and regions will also gradually increase.

There are many manufacturers of injection molding machines in China. According to incomplete statistics, there are more than 3,000 manufacturers. There are two types of injection molding machines: vertical and horizontal. According to the products produced, they can be divided into ordinary injection molding machines and precision injection molding machines. The injection volume is 18-51000g; the clamping force is 30-36000kN; the processing materials are thermosetting plastics, thermoplastics and rubber. Thermoplastics include polystyrene, polyethylene, polypropylene, nylon, polyurethane, polycarbonate, organic glass, polysulfone and (acrylonitrile/butadiene/styrene) copolymer (ABS). From the perspective of processed products, there are single-color and two-color general and precision plastic products.

Ordinary horizontal injection molding machines are still the dominant direction of the development of injection molding machines, and their basic structure has hardly changed. In addition to continuing to improve their control and automation levels and reduce energy consumption, manufacturers are developing in the direction of combined series according to market changes. For example, the same model of injection molding machine is equipped with large, medium and small injection devices, which are combined into standard and combined types, increasing flexibility, expanding the scope of use, and improving economic benefits.

Injection molding machine manufacturers in industrially developed countries are constantly improving the functions, quality, supporting capacity of auxiliary equipment, and automation level of ordinary injection molding machines. At the same time, they are vigorously developing and developing large-scale injection molding machines, special injection molding machines, reaction injection molding machines, and precision injection molding machines to meet the needs of producing plastic alloys, magnetic plastics, and plastic products with inserts.

Injection molding machines are one of the fastest growing plastic machinery types in China, and their level is relatively close to that of industrially developed countries. However, they mainly refer to ordinary injection molding machines. In terms of most types of extra-large, various special, dedicated, and precision injection molding machines, some products are still blank, which is the main gap with industrially developed countries.