Injection Molding Machine: How It Works

SS Machinery

Injection molding is an important method of manufacturing plastic parts, and injection molding machines are necessary equipment for injection molding. With the continuous development of social economy, the demand for plastic products is increasing, so this process has a broad prospect and market. Injection molding technology is widely used in various industries such as aerospace, medical equipment and automobiles, and even the most complex parts can be manufactured with impeccable precision. Millions of companies are using it to implement their part designs. Why do I need an injection molding machine? How does it work? Before buying or using an injection molding machine, it is very necessary to understand the working principle of the injection molding machine and the entire injection molding process.

What is an injection molding machine

An injection molding machine is a complex machine that uses a reciprocating screw system to inject molten material into a mold to make solid parts. This machine is composed of multiple parts; it is mainly composed of a hopper, a barrel equipped with a reciprocating screw, a temperature control device, a mold clamping device and the injection mold itself.

Work flow of injection molding machine

The working principle of the injection molding machine is to operate the plastic powder or granules according to the requirements and sizes to form them into parts. The injection molding process starts with the injection of molten plastic into the mold. The raw materials and colors are fed into the barrel of the machine through the hopper. In the barrel, the raw material is affected by pressure and temperature, making it melt and ductile. The reciprocating screw in the barrel will rotate to inject a precise amount of molten plastic into the injection mold at a set and controlled temperature, pressure, and speed. Once the mold is filled with molten plastic, the injection process will be closed. Then let the part cool down until it is ready to be removed from the mold. This may take some time, depending on the material, wall thickness, overall size and shape of the manufactured part. After cooling, the mold will automatically open. The mold has a built-in ejection mechanism, which can eject parts and prepare for a new cycle. If part of the finished part is still stuck in the mold at this time, the mold will reopen until the part is completely ejected. When the parts leave the machine, the hopper will release more raw materials and colors into the barrel, and a new cycle will begin. Injection molding machines are usually programmed and do not need to be supervised at all times during operation.

Now the injection molding machine has rapidly developed into an efficient and multifunctional tool for manufacturing daily necessities. The basic principle behind the injection molding machine may seem simple, but in fact, this is a very complex machine that requires professional learning and appropriate expertise. However, if executed properly, injection molding can consistently produce products even for the most challenging manufacturing projects.

Features of injection molding machine

Next we introduce the advantages and disadvantages of injection molding machines.

Advantages of injection molding machine

  • Automation

    One of the main reasons that injection molding produces consistent results is that many actual manufacturing processes can be automated. This means that you can not only minimize the possibility of human error, but also allow the machine to produce parts at a consistent speed and high completion rate.

  • Accuracy

    Since the injection molding machine injects the material into the mold and then forms it by the mold, the number of defects can be reduced to a minimum. This means that in each run, you can produce the same part as the previous one over and over again.

    As mentioned earlier, injection molding machines enable companies to produce the most complex mold designs, even the smallest details can be easily executed.

    Such precision and detail are very important in almost all industries, especially those industries that have strict requirements on quality. This is also the reason why injection molding machines are widely used in high-demand fields such as aerospace and automobiles.

  • Cost-effectiveness

    In most cases, injection molding is one of the most cost-effective solutions for producing parts.

    Although the bottom line of your project depends on the materials you use and the complexity of the design, when you compare it with other manufacturing methods, you will usually find that the speed and automation of the injection molding machine can bring you lower cost per room .

  • Wide range of materials

    If injection molding is really good at one thing, it is the ability to customize materials and finishes according to almost any type of requirement. You can choose plastics, thermoplastic rubbers, chemical resistant plastics, biodegradable plastics and other materials, so be sure to figure out what you need from the parts. You will have many choices.

    You can also choose almost any color imaginable, or choose from a variety of finishes, whether for aesthetic or functional purposes.

Limitations of injection molding machines

  • Mold design

    Since the mold needs to be designed and manufactured, this process takes time and cannot be omitted. Sometimes it may take several months to complete, depending on how complex your project is.

  • Size limit

    In most cases, although the injection molding machine can produce quite large parts up to 60 cubic inches or so, your parts can be within the manufacturing range of the injection molding machine, but if you need larger parts, you may need to choose another Table manufacturing methods, such as plastic manufacturing.

  • High initial cost

    As mentioned above, injection molding production is very cost-effective, especially for larger production runs, because the cost of parts is relatively low. However, the price of the injection molding machine itself is very high, so the purchase of an injection molding machine is a very important investment, and it is very important to choose a suitable injection molding machine.

    Before actual manufacturing, you need to choose the right injection molding machine, which is just a big investment; you need to design and create the mold yourself, which may take a lot of time and a lot of manpower to execute correctly.


The above is the working principle and process of the injection molding machine, as well as its advantages and disadvantages.

If you want to buy excellent injection molding machine products, you can choose injection molding machines made in China. Choosing a Chinese-made injection molding machine can save you a lot of costs, because a Chinese-made injection molding machine can provide the same product quality at a lower price.

There are many excellent manufacturers of injection molding machines in China. You can read the Top Ten Brands of Injection Molding Machines in China to learn more. Among them, we recommend Shuangsheng, China's top injection molding machine manufacturer. Shuangsheng has successively obtained invention patents and more than ten utility model patents by virtue of its strong scientific research ability, precise production technology and professional service system. We continue to develop and research new production technologies to meet market demand and meet customers' different functional requirements for machinery. In the past 18 years, the Shuangsheng brand has also been recognized and evaluated by customers all over the world.

If you are interested, you can contact us immediately to get the latest consultation and product details.

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