What are injection molding machines ? What are the types?

What are injection molding machines ?  What are the types?
Do you know how the plastic products in life are made? Many of the bottle caps, bowls and plates, auto parts, etc. are injected with injection molding machines. When it comes to injection molding machines, many people may have no picture in their minds. A small number of people may think that it should be similar as making egg cakes. For the egg cake, put the egg liquid into the iron mold with cartoon design and start heating it. After forming, taking it out one by one ! This analogy is that the picture is one of the injection molding methods. There is nothing wrong with the injection molding machine. Not only plastic products can be manufactured by the injection molding machine. The machine used is not as simple as the one used by grandma to make egg cakes. In this article, we sort out common injection molding machine.  What are the different features of different models? Let's take a look at our following sharing.

What are injection molding machines ?

Injection molding machines, also called injection machines, are special machine for manufacturing plastic products. Most injection machines are mainly composed of two parts: injection device and clamping unit. The injection unit is responsible for heating the poured plastic pellets into liquid. The clamping unit is used to carry the mold and provide the force required for mold closing and clamping. Generally speaking, the injection molding machine has the advantages of rapid processing and economic benefits.
〈Extended reading: How to choose the injection machine? 8 key points let you choose the right injection molding machine!

There are many types of injection molding machines, usually the following methods can be used to distinguish:

Classification method 1: Drive type

Hydraulic injection molding machine

The injection power of the hydraulic injection machine is mainly hydraulic. The characteristic is that the machine is cheaper. It can also be used to make larger appliances such as car bumpers and multi-piece molds. However, the disadvantage is that the cost of machine production and maintenance is high. Because the hydraulic plastic injection molding machine cannot be left idle, it needs to be kept running all the time, otherwise the machine may break down; while making plastic components, it is also necessary to control and adjust the temperature of the machine, otherwise it is easy to make scraps.

All-electric injection molding machine

Compared with the hydraulic injection machine, the price of the all-electric injection molding machine is higher. However, the all-electric injection machine does not require standby operation or temperature adjustment, so the injection molded product is relatively stable and can be more efficient. The all-electric injection molding machine does not have a hydraulic system, and there is no risk of liquid leakage in the machine.

Hybrid/Servo Hybrid Injection Molding Machine

The hybrid injection molding machine has the characteristics of high efficiency and economic benefits. It is a modified model that integrates the advantages of hydraulic/all-electric injection molding machines. It is used by many companies now, which balances the other two types. The advantages and disadvantages of hydraulic presses include medium machine cost and energy cost. We all know that energy cost is definitely a major consideration when choosing an injection molding machine. For this purpose, the servo-hydraulic injection molding machine is equipped with a high-precision servo motor to achieve the same power saving as the full-motor type. Considering the cost, the machine and clamping mechanism are also simpler, more accurate and durable, which greatly reduces the cost of maintenance. Servo-electric injection molding machine not only has the advantages of cost saving, but also has a higher injection and pressure holding pressure than the full-motor type, which is a major breakthrough in the hydraulic injection molding machine.

Classification method 2: Clamping direction

Vertical injection molding machine

As the name suggests, the vertical injection molding machine is a vertical injection molding machine. It is usually used to manufacture relatively small molds. It has the advantages of being able to inject more types of products and saving space. If the vertical injection molding machine is equipped with a rotating table or conveyor belt, it can effectively improve production efficiency.

Horizontal injection molding machine

The horizontal injection machine is now the most widely used and the most used model. The features is  low body, fast molding, and convenient operation and maintenance. As the plastic parts will automatically fall after being pushed out, it can reply the need of auto-production.

Classification method 3: Applicable raw materials

Thermoplastic injection molding machine

Thermoplastics will melt and become liquid after heating, and become solid when they become cold. Common thermoplastics include PE, PP, ABS, TPU, etc. Generally, the plastics that become soft when exposed to heat are mostly thermoplastics. The thermoplastic injection machine uses the characteristics of thermoplastics to inject liquid plastic into the mold after the plastic pellets are heated. After cooling, the plastic returns to a solid state, and then the plastic parts are pushed out of the machine.

Thermosetting Plastic Injection Molding Machine

The characteristic of thermoset plastics is that they will change from liquid to solid after heating. This conversion can usually only be formed once and cannot be recycled like thermoplastics. Therefore, it is not environmentally friendly. Common thermoset plastics include FRP and melamine. The thermosetting plastic injection machine is to inject the plastic liquid into the mold after being processed, and then heat the plastic part to solidify and complete the production.

Powder injection molding machine

Powder injection molding can also be called "metal injection molding" (MIM) or "ceramic injection molding" (CIM). The raw materials are finely processed fine metal or ceramic powders and joining materials. Common applications are portable products, smart devices, electronic products, etc. Powder injection is often used to manufacture small parts with high precision and complex appearance, especially metal powder injection parts have the characteristics of high strength and high density. After the metal powder and bonding materials of the powder injection machine are processed, they will become small molding materials similar to plastic pellets. Then the injection molded parts will be cleaned, heated, etc. Post-processing, and finally complete the production of the workpiece.

Classification method 4: Clamping structure

Single Cylinder/Double Cylinder/Four Cylinder Direct clamping Injection Molding Machine

Direct-pressure injection machines are also divided into single-cylinder, double-cylinder, and four-cylinder models based on the number of hydraulic cylinders. Because the single-cylinder type hydraulic cylinder has a large area, the production of parts will be more difficult, so the single-cylinder model will have a lot of problems when used in large machines. Also, because the single-cylinder model is usually directly pressed on the mold, the mold's accuracy is very important. Insufficient precision will directly affect the accuracy of mold clamping. At present, single-cylinder direct pressure injection machines have been slowly replaced by multiple-cylinder direct pressure injection machines. Double-cylinder injection means that two cylinders do the injection in parallel. Generally, the injection speed of the double-cylinder will be slower than that of the single-cylinder under the same pressure, but the injection pressure will increase. The template design of the four-cylinder direct pressure mold clamping is different, and the oil cylinder also has an automatic balance correction function, so it does not affect the accuracy of the mold clamping, and the applicable range is relatively large. In the past, the most common problem with four-cylinder direct pressure mold clamping models was imbalance in force, which caused mold damage and product dimensions that could not meet the requirements. However, most of this problem can be greatly improved as long as the parts are processed accurately. Compared with the toggle type injection machine, the direct pressure type injection machine has a long mold life, can be directly locked, and there is no resistance when working, so there is no need for frequent lubrication, and the maintenance cost is low. Although the machine is better than the toggle type injection molding machine, the machine is more expensive, and the feature is that it is more durable than the toggle injection machine.

Toggle Type Injection Molding Machine

Toggle type injection machines are characterized by their acceleration and deceleration functions, simple operation, lower operating costs and lower machine costs, but compared to direct pressure injection molding machines, the toggle type injection machines use molds and the machine itself. The lie time is relatively low, and the structure of the machine is also more complicated.

Composite direct clamping injection molding machine

The components injected by the composite direct pressure injection machine are the same as the direct pressure injection machine. As the longer machine has a large mold opening force, the longer clamping stroke can be designed. However, the clamping structure is more complicated, and because of the complex structure, the durability of components is a huge test, and only few manufacturers currently mass produce them.

Classification method 5: Injection structure

Single-color injection molding machine (a group of injection Single-Component)

Monochrome injection means that the entire plastic component is of the same color during injection. Monochrome injection machines are currently common used. Monochrome injection can also be used to inject products with two different colors. The single-color injection molding machine uses the first color to inject the first semi-finished product, and then uses the second color to process the semi-finished product to complete the production.

Multi-color Injection Molding Machine (Multi-Component Injection)

Multi-color injection machines can simultaneously inject plastic components with more than two different colors. The most widely used multi-color injection molding machine is two-color injection molding machines. After years of improvement, multi-color injection molding machines have also developed sandwich injection, cube molds, or as an application combined with LSR silicone rubber. Multi-color injection technology has gradually become a hot trend in the industry in recent years because of its environmental protection, high efficiency, and good performance.


So many kinds of injection molding machines have been introduced. Do you have a preliminary understanding of plastic molding machines? If you are worrying about which injection molding machine you should use for the product you want to produce, you can first think about the characteristics of the product, the company's budget, use, and permanence. Each type of injection molding machine has advantages and disadvantages. For example, if the company has a certain budget for electricity, it can choose the type of injection molding machine that is more power-saving. If there is a certain requirement for the precision of molding, it can consider as the first priority.

EDEX, we are a professional injection molding machine integration company, dedicated to the development and integration of injection molding machine technology, feel free to contact us if you have any needs.
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