Injection molding machines - comprehensive guide 2025

Introduction to injection molding technology

Plastic injection molding technology is revolutionizing modern industry, enabling mass production of precision plastic components. Injection molding machines are a key tool in this process, finding application in almost every industry - from automotive, through electronics, to medical and cosmetics industries.

In this comprehensive guide, we will present everything you need to know about injection molding machines. You will learn what types of injection molding machines exist, how they work, what their key technical parameters are, and how to choose the right machine for your production.

What is an injection molding machine?

An injection molding machine (injection molding machine) is an advanced industrial device used to produce plastic products by injection molding. The process involves heating plastic granulate to a plastic state, then injecting it under high pressure into an injection mold, where the material solidifies taking the desired shape.

Modern injection molding machines are precise machines equipped with advanced control systems that allow production of very high quality and repeatability components. Thanks to process automation, it is possible to produce thousands of identical components with minimal operator involvement.

History of injection molding machine development

The history of injection molding machines dates back to the 19th century. The first injection molding machine was patented by John Wesley Hyatt in 1872 in the United States. It was a relatively simple structure used to produce celluloid buttons. The real breakthrough came in 1946, when James Watson Hendry built the first injection molding machine with a screw, which significantly improved mixing and plasticizing quality.

In the 1950s, dynamic development of injection molding technology began. Hydraulic injection molding machines were introduced, which dominated the market for many decades. The following decades brought development of control systems, automation and process precision.

The 1990s was the era of electric injection molding machines, which revolutionized the industry thanks to much higher precision, repeatability and energy savings. Currently we are observing further technology development, including hybrid injection molding machines combining advantages of hydraulic and electric systems.

Types of injection molding machines

Various types of injection molding machines are available on the market, differing primarily in drive type. Each type has its unique features, advantages and applications. Understanding the differences between them is crucial when choosing the right machine for specific production needs.

Hydraulic injection molding machines

Hydraulic injection molding machines are the oldest and still very popular type of molding machines. They use a hydraulic system to drive all machine movements - both injection and clamping units. The main element is a hydraulic pump supplying pressurized oil to hydraulic cylinders.

Advantages of hydraulic injection molding machines:

• High clamping force - ability to achieve very large forces at relatively low costs
• Lower purchase price - are usually cheaper than electric equivalents
• Simple construction - easier to service and repair
• Proven system - many years of operation experience
• Ability to work at high loads

Disadvantages of hydraulic injection molding machines:

• Higher energy consumption - consume a lot of power even when idling
• Lower precision - compared to electric systems
• Need for hydraulic system maintenance - oil change, filters
• Noise - hydraulic pump generates significant sound level
• Risk of oil leaks - may affect production cleanliness

Electric injection molding machines

Electric injection molding machines use servomotors to drive all machine axes. Thanks to this they achieve exceptional precision and process repeatability. This is the most modern type of molding machines, which is enjoying growing popularity, especially in production requiring high quality.

Advantages of electric injection molding machines:

• Very high precision - accurate positioning and parameter control
• Energy savings - up to 70% lower power consumption compared to hydraulic
• High repeatability - identical parameters for each cycle
• Production cleanliness - no oil, ideal for medical and food industries
• Low noise level - quieter operation
• Shorter cycle times - faster movements and responses

Disadvantages of electric injection molding machines:

• Higher purchase price - even 30-50% more expensive
• More complex service - requires specialist knowledge
• Limitations in very high clamping forces

Hybrid injection molding machines

Hybrid injection molding machines combine advantages of hydraulic and electric systems. Most often the injection unit is electrically driven (for precision), and the clamping unit hydraulically (for high forces). This is a compromise between performance, precision and cost.

Advantages of hybrid injection molding machines:

• Operating cost optimization - lower energy consumption than fully hydraulic
• Good injection precision - thanks to electric injection unit
• High clamping forces - thanks to hydraulic clamping unit
• Reasonable price - cheaper than fully electric

Construction and main components of injection molding machine

Every injection molding machine consists of two main parts: injection unit and clamping unit. Understanding the construction and function of individual elements is crucial for effective use of the machine.

Injection unit

The injection unit is responsible for preparing plastic and injecting it into the mold. It consists of the following elements:

• Hopper - container for plastic granulate
• Plasticizing cylinder - where heating and mixing of plastic takes place
• Injection screw - rotating-reciprocating element transporting and homogenizing plastic
• Heating zones - usually 3-5 zones with separate resistance heaters
• Injection nozzle - tip connecting to the mold
• Pressing system - presses nozzle to mold during injection

The process in the injection unit proceeds in stages: granulate is fed from the hopper to the cylinder, where it is heated and mixed by the rotating screw. When the appropriate portion of molten plastic is collected, the screw moves forward and injects material into the mold under high pressure.

Clamping unit

The clamping unit is responsible for closing and opening the mold and maintaining appropriate clamping force during injection. Main elements are:

• Fixed platen - mounted directly to machine frame
• Moving platen - moves during mold opening and closing
• Guide columns - ensure parallel motion guidance
• Toggle or hydraulic mechanism - generates clamping force
• Ejectors - ejection system for removing molded part from mold

Key technical parameters

When choosing an injection molding machine, attention should be paid to several key technical parameters:

1. Clamping force (kN or ton)

This is the maximum force the machine can exert on the injection mold. Typically from 200 kN to 70,000 kN. The force must be matched to the projected area of the molded part and injection pressure. Too little force will cause mold opening and flash, too much - unnecessary energy consumption.

2. Injection volume (cm³ or g)

Maximum volume of plastic the machine can inject in one cycle. Should be adapted to molded part size with 20-80% safety buffer.

3. Injection pressure (MPa or bar)

Maximum pressure achievable during injection. Typically 100-250 MPa. Higher pressure allows filling more complex molds and achieving better surface quality.

4. Screw diameter and L/D ratio

Screw diameter (e.g. 40mm, 60mm) affects plasticizing performance. Length to diameter ratio (L/D) typically is 18-24:1.

5. Platen spacing

Determines maximum mold dimension that can be mounted in the machine.

6. Cycle time

Total time for producing one molded part (closing, injection, holding, cooling, opening, ejection). Directly affects production efficiency.

Applications of injection molding machines

Injection molding machines find application in virtually all branches of industry. Here are the most important ones:

Automotive industry

Production of car interior elements (dashboards, door panels, consoles), exterior parts (bumpers, lights), engine components. Automotive part injection requires highest quality and precision.

Electronics and electrical engineering

Electronic device housings, connectors, plugs, buttons, insulating elements. Electronic component injection must meet rigorous cleanliness standards.

Medical industry

Disposable medical tools, syringes, diagnostic device elements. Medical injection requires sterile conditions and certified materials.

Packaging

Bottles, containers, lids, closures, cosmetic packaging. Packaging injection is one of the largest market segments.

AGD industry

Household appliance housings, washing machine, refrigerator, vacuum cleaner elements. AGD part injection requires temperature and chemical resistance.

Toys and children's articles

Blocks, figurines, toy elements. Toy injection is subject to special safety standards.

Household articles

Containers, buckets, organizers, kitchen accessories. Household article injection is mass production requiring short cycle times.

How to choose the right injection molding machine?

Choosing the right injection molding machine is a key investment decision. A number of factors should be taken into account:

1. Product analysis

• Dimensions and weight of molded part
• Type of plastic
• Quality requirements and tolerances
• Geometry complexity

2. Production requirements

• Planned production volume (pieces/day)
• Production type (series, small-batch)
• Number of product variants
• Possibility of product range development

3. Budget and ROI

• Machine purchase cost
• Operating costs (energy, maintenance)
• Return on investment time
• Availability of service and spare parts

4. Drive type selection

• Hydraulic - when priority is low purchase cost and high forces
• Electric - when precision, energy saving and cleanliness matter
• Hybrid - as a compromise between performance and cost

5. Cooperation with supplier

• Manufacturer's experience and reputation
• Technical service quality
• Operator training
• Support in production startup

Maintenance and upkeep

Proper maintenance of injection molding machine is key to long and trouble-free machine operation. Recommended actions:

Daily activities:

• Hydraulic oil level check
• Heater temperature verification
• Injection nozzle cleaning
• Visual leak inspection

Weekly:

• Lubrication of guides and columns
• Air filter cleaning
• System tightness inspection

Monthly:

• Screw and cylinder wear inspection
• Hydraulic system pressure check
• Cooling fan cleaning

Annual (major inspection):

• Hydraulic oil and filter replacement
• All electrical connection inspection
• Platen parallelism check
• Seal inspection and replacement

Summary

Injection molding machines are an integral element of modern plastics industry. Choosing the right molding machine requires thorough analysis of production needs, technical parameters and budget.

Key conclusions from the guide:

• Drive type - hydraulic for high forces, electric for precision, hybrid as compromise
• Technical parameters - clamping force, injection volume and pressure must be matched to product
• Application - different industries have different quality requirements
• Maintenance - regular inspections ensure long machine life
• Supplier - choosing a reputable partner guarantees technical support

If you need help choosing the right injection molding machine for your production, contact TEDESolutions experts. As an authorized partner of Tederic, we offer comprehensive consulting, sales and service of highest quality molding machines.

We also invite you to read the following articles in our series on plastics processing, where we discuss injection molds, injection process and practical aspects of production in detail.