There are three basic types of injection-molding machines: Hydraulic, mechanical, and electric. We will also cover the Plunger Type Injection Molding Machine, Screw Plunger Type Injection Molding, Plunger-Plunger Type Injection Molding, and Reciprocating Screw Injection Molding in this article.

 Each one of these types has its advantages and disadvantages. To understand each type, read on. This article is not intended to be a complete guide to each of the types. Nevertheless, we will try to provide a general overview of each type and what each one is used for.

Hydraulic

While electric drives are superior in controlling position, velocity, and acceleration, hydraulic injection-molding machines have their own advantages. Electric machines also have their technical limitations and are only suitable for certain injection molding applications. Some manufacturers, such as LG International and GO4Mould manufacture hybrids and full hydraulics. 

Read on to learn about the advantages and disadvantages of hydraulic injection-molding machines. Here is a brief summary of the differences between these two machines.

Injection molding requires a hydraulic pressure to apply the clamping force. A pressure transducer feeds a signal to the controller, which controls the clamping pressure accordingly.

 In the past, manual adjustment of the pressure-reducing valve resulted in excessively high pressure, especially when the product is small. High pressure can stress cylinders and seals and shorten their life span. A hydraulic injection-molding machine should be capable of producing small products with a relatively low pressure.

For accuracy, a hydraulic injection-molding machine should have a programmable controller to regulate the pressure on the plunge cylinder and the screw. Proper pressure control is essential for the smooth flow of plasticized material into the mold. The hydraulic pressure should not be too high or too low; otherwise, it can cause quality problems. To make sure that the pressure is the correct one, you should invest in a high-quality hydraulic injection-molding machine.

Mechanical

The global market for Mechanical Injection-Molding Machines is segmented by region. The region of North America is expected to hold the largest share of the market by 2030, owing to its advanced infrastructure and rising demand from the aerospace and automotive industries.

 The Asia Pacific region is further divided into Japan, China, India, South Korea, and other regions. The Middle East and Africa region is subdivided into South Africa and GCC.

Injection molding machines are classified into two types: mechanical and hydraulic. The former is usually characterized by a screw-driven mechanism. It moves the molding material continuously. 

The latter has a hydraulic system that applies pressure to a fixed-displacement pump. In both types, valves control the pressure of the system. They are available in a variety of sizes and can be customized to fit your manufacturing needs. 

If you are looking for an injection-molding machine, you should check the specifications of your machine before investing in one.

A mechanical interlock mechanism is used to prevent accidental die displacement. This mechanism comprises a push rod that extends from a movable die carrier frame. 

The rod is connected to toothed jaws that can engage with the arresting rods and prevent the rods from advancing further. The safety cover opens and closes using a control rod and moves by cooperating cam followers and drive links. For safety, a tamper-proof safety cover is used.

Electric

When selecting an electric injection molding machine, there are a few things to consider. The most important of these is the clamping unit, which should be powerful enough to hold the mold shut during the injection process. 

If you are working with thin-wall sections, this unit must be able to supply three to four tons of clamp force per square inch of the cavity. If you have thicker wall sections, you may want to consider a machine with two or more tons of clamp force.

One manufacturer that offers electric IMMs is Sumitomo (SHI) Demag. These machines range from twenty to 936 U.S. tons and feature high-speed injection, two-shot machines, and vertical inserts.

The machines feature a wide variety of features, including low maintenance and increased productivity. Other benefits include easy operation, high-performance control, and a longer tie bar. These machines also have several safety features, including a lockout capability and extended tie bars.

Electric injection molding machines have many advantages. First of all, they provide a completely clean environment. They are perfect for molders that manufacture food packaging or medical products. 

Additionally, they do not require oil filters or oil filtering systems, which makes them ideal for molders in those fields. Second, they are quiet, with Milacron electric machines running at 70 dB, or the noise level of an office copier. This means that they will not disturb other workers or the environment.

There are also 4 types of Injection Molding machines:

Injection molding machines come in various shapes and sizes. There are four types of injection molding machines: Plunger Type Injection Molding Machine, Screw Plunger Type Injection Molding, Plunger-Plunger Type Injection Molding, Reciprocating Screw Injection Molding. Each type has its own unique benefits and drawbacks. Which type is best for your business depends on the products you plan to produce.

Plunger Type Injection Molding Machine:

The Plunger Type Injection Molding Machine is a common industrial machine for producing plastic products. It has three main parts: the clamping unit, the platen, and the injection seat. 

The clamping unit is directly connected to the moving platen by a toggle mechanism. The force generated by direct fluid pressure opens and closes the mold, while the plunger keeps the mold closed during the injection process.

The plunger-type injection molding machine comes in both vertical and horizontal designs. This machine is operated hydraulically or pneumatically. In some machines, the clamping and injection are automatically controlled.

The cylinders connect to a clamping mechanism that moves the tooling. Automatic type cylinders automatically activate the clamping and injection mechanisms at pre-set times. On the other hand, screw-type injection molding machines consist of a reciprocating screw & barrel assembly, an injection nozzle, a hopper, and a press. The plastic is injected into the mold cavity through fittings on the machine.

The Plunger Type Injection Molding Machine can be divided into two main types: screw and plunger. Both have the same function but differ in their design and features. A plunger-type machine does not have a screw in the plasticizing chamber, so the plunger-type is generally more expensive than its counterparts. If you’re looking for an injection machine for plastic products, it is good to choose one with the plunger-type.

Screw Plunger Type Injection Molding

There are two basic types of plastic injection molding machines: the screw plunger type and the plunger-type. The former uses heaters to plasticize the raw material. While the latter uses a screw to force the plastic material into a mold cavity. Both types have similar functions, but the screw plunger is more efficient.

Heat is provided by a band heater located over the barrel. After the raw material is heated, it is pushed into the mold cavity by a plunger. Once inside the mold cavity, the plasticized material will be set into the mold.

The screw plunger-type injection molding machine is a coaxial design that overcomes the limitations of the prior art. The screw plunger is simple to construct and the difference in temperature that the material melts forms is small enough that the material precursor will be poured out first. 

This ensures uniformity and concordance for the same workpiece material. However, unlike the coaxial model, the screw plunger does not have any moving parts.

The V-LINE injector has closed-loop control. It monitors actual speed versus set speed and maximum melt pressure. A linear encoder and pressure sensor detect the plunger position and the injection pressure. 

The software also provides user selectable limits that are input into the process monitor screen. The plunger retracts itself by a thermal force from the material and returns to its set position. This system eliminates the need for a check valve. It provides real-time response and records the melt cushion in 0.001” increments.

Plunger-Plunger Type Injection Molding

Plunger-Plunger Type Injectables are manufactured through a process known as Injection Molding. The process uses thermosetting plastics. The first machine of this type was introduced by Interplas in 1961. Later, it became popular in the thermosetting polyester molding compound industry. Since then, this process has been widely used to produce thermoplastics and has been the most common type of injection molding.

The clamping unit is directly connected to the moving platen. Its function is to apply direct fluid pressure to the clamping unit to open and close the mold. This clamping force holds the mold closed during the injection process. However, it has some disadvantages as well. Here are some of them:

The first major disadvantage of this type of injection molding is its slow cycle. Compared to the other types of injection molding, Plunger-Plunger Type Injection Molding requires less labor and is a cost-effective option. The Plunger-Plunger Type Injection Molding process can be categorized into two main types: thermoplastic and clamping. The thermoplastic is injected into the mold and high pressure is applied to form the desired shape.

Reciprocating Screw Injection Molding

Reciprocating screw injection molding machines can produce various types of plastic parts. They typically feature electric heater bands that heat up the cylinder and barrel, as well as a conventional nozzle assembly that engages a sprue bushing. 

These machines are ideal for producing high-quality plastic parts that are consistent in shape, size, and color. The most common model of a reciprocating screw machine produces a wide range of thermoplastic products.

The two main functions of a reciprocating screw injection molding machine are melting and injecting. The machine holds a product and rotates back and forth to inject the polymer. 

The rotational motion of the barrel produces sheer torque. The barrel is heated with electric heaters, which melt the pellets inside it. The heated plastic pellets are then inserted into the mold cavity and the product is formed inside the sprue or cavity.

The reciprocating screw process melts plastic and deposits it in front of a feed screw at the nozzle end. As the material builds up to the desired shot size, the feed screw retracts and advances axially toward the nozzle. 

The material in front of the piston head then enters the mold. The process also incorporates a check valve, which prevents the material from flowing backward during the injection stroke.

Each of those types has its own benefits and drawbacks that should be considered when choosing the right machine for your needs. Reciprocating screws are good for producing large quantities of parts quickly and with consistent quality. Plungers are great for small batches or products with intricate details due to their high degree of accuracy. Rotaries are perfect for high-volume production with a wide range of part sizes.