Design and Main Components

An injection molding machine is generally composed of several subassemblies that together enable the injection molding process. The most important components include:

• Closing unit: It keeps the mold closed during injection.
• Injection unit (plasticizing unit): This is where the plastic is melted and injected.
• Mold: Gives the part its shape.
• Drive system: Generates the machine's movements and forces.
• Control System: The "brain" of the machine.

What types of injection molding machines are there?

Injection molding machines can be classified according to various criteria, primarily by drive type, design, number of injection units, and application.

Depending on the drive system, injection molding machines are classified as hydraulic, electric, or hybrid:

• Hydraulic machines operate using hydraulic oil and can generate very high clamping forces. They are robust and proven, but consume more energy and are comparatively noisy. 
• Electric injection molding machines use servo motors for all movements, which makes them particularly precise, energy-efficient, and quiet.
• Hybrid machines combine hydraulic and electric drives, offering high power output and good energy efficiency.

Based on the construction method, machines are classified as either frame-type or frameless:

• Four-beam machines, the classic design, have four beams and are very sturdy and versatile. 
• Columnless machines, on the other hand, do not have columns, offer better access to the mold, and provide even clamping force distribution, which is particularly advantageous for large or complex molds.

Another distinguishing feature is the number of injection units:

• Most machines are single-screw machines with a single injection unit, which is sufficient for standard parts. 
• Multi-component or 2K/3K machines have two or more injection units and enable the production of parts made from multiple plastics or colors, such as hard-soft combinations.

Finally, injection molding machines can be classified based on the plastic they process:

• Thermoplastic injection molding machines are designed for processing thermoplastics such as polypropylene, polyamide, or ABS.
• Thermoset machines are used for thermosets and operate with heated molds. 
• Elastomer or LSR machines are designed specifically for rubber or silicone and feature special screws and molds. 

In addition, there are special-purpose machines, such as micro-injection molding machines for very small parts, vertical injection molding machines for insert molding or overmolding, and machines for reaction injection molding (RIM).

Advantages & & Disadvantages of Injection Molding

Injection molding is a widely used process for manufacturing plastic parts and offers numerous advantages. Its high precision and repeatability are particularly noteworthy. It has a high production speed, making the process especially well-suited for mass production. 

In addition, injection molding results in minimal material loss, as excess plastic can often be recycled. The surface quality of the finished parts is also very good, and it is possible to produce complex geometries and integrated features such as undercuts, ribs, or hinges. The process is also highly versatile, as many different plastics can be processed on injection molding machines.

Left: Arburg Allrounder 475 V vertical injection molding machine

Right: Beamless electric clamps, Victory Electric 220, with a clamping force of 2,200 kN

On the other hand, injection molding also has some disadvantages. The initial costs for machines and molds are high, especially for multi-component or high-precision machines. Mold manufacturing is time-consuming and expensive, which makes the process less economical for small production runs. 

In addition, the process requires precise process control, as even small deviations in temperature, pressure, or cooling can lead to dimensional or quality defects. Flexibility in adapting to design changes is also limited, since the mold must be remade for each new part.

Applications & Products

Injection molding machines are used wherever large quantities of identical plastic parts are needed. They are one of the most important processes in plastics processing because they are fast, precise, and versatile.

Real-World Examples

• The bicycle handlebars for Canyon Bicycles are manufactured on an Engel Victory 180 column-less injection molding machine. Read more

• Sustainable Packaging Meets Design: Thomriss Relys on Wittmann Technology for Precise, Efficient, and Eco-Friendly Cosmetics Packaging. Read more

• It took skateboarder Peter Karacsonyi more than ten years of development: With the help of Krauss Maffei, he has created the perfect skateboard. Read more (+)

Conclusion

Injection molding machines are among the most important pieces of production equipment in modern industry, as they enable the cost-effective production of plastic parts in large quantities. A key advantage of injection molding is its high precision and repeatability, which allow even complex components to be manufactured with consistent quality. In addition, the process enables short cycle times, resulting in very high productivity and making it particularly attractive for mass production.

Another major advantage is the high degree of design freedom. Injection molding machines can be used to produce both simple and highly complex geometries, including components with integrated features such as clips, hinges, or reinforcing ribs. At the same time, material loss is minimal, as excess plastic can often be recycled. The ability to process different plastics as well as multi-component or hard-soft combinations makes the process extremely versatile.

Because of these characteristics, injection molding machines are used in numerous industries, such as the automotive industry, the packaging industry, medical technology, electrical engineering, and the household and consumer goods sectors. In any application where precise, durable, and cost-effective plastic parts are needed in large quantities, injection molding machines are the preferred solution.