What Is an All-Electric Injection Molding Machine: Definition and Characteristics

What is an All-Electric Injection Molding Machine?

An all-electric injection molding machine is a molding device driven entirely by servo motors. Unlike traditional hydraulic injection molding machines, an all-electric machine does not rely on a hydraulic oil system, but uses multiple independent servo motors to control various actions such as feeding, injection, mold closing, and ejection.

In simple terms, if a traditional hydraulic injection molding machine is compared to a "petroleum-driven industrial giant," then an all-electric injection molding machine is like a "precisely controlled robot." This type of equipment is not only quieter and cleaner but also offers higher repeatability and faster response times.

The Invention of the First All-Electric Injection Molding Machine

Driving Force:

In the 1970s, the ongoing oil crisis forced the industrial sector to reexamine energy efficiency issues. Traditional hydraulic injection molding machines, while stable, consumed a lot of energy—about 1.2 kWh of electricity to produce 1 kg of product—and also faced the problem of hydraulic oil leakage and pollution. With increasingly stringent environmental regulations, energy efficiency became a critical issue for industries worldwide.

Technological Breakthrough:

In 1982, Japan's Sumitomo Heavy Industries introduced the first all-electric injection molding machine (SE-DUO series), completely eliminating hydraulic drive. By using high-response servo motors to directly drive the injection screw and mold closing mechanism, the precision of the injection molding process was improved to ±0.05 mm, and energy consumption was reduced by about 40%. This technological breakthrough marked a significant step towards environmentally friendly, energy-efficient, and precise injection molding technology.

Initial Application and Resistance to Adoption:

Despite the huge advantages of all-electric injection molding machines in terms of precision and efficiency, their high initial cost—2-3 times that of traditional hydraulic machines—meant they were mainly used in industries with high demands for precision and cleanliness, such as medical devices and electronic components. As market demand for precision production increased and technological advancements reduced costs, all-electric machines gradually gained acceptance across more industries.

How Does an All-Electric Injection Molding Machine Work?

The working principle of an all-electric injection molding machine is similar to that of a traditional hydraulic injection molding machine, with the main difference being the drive system. All-electric models use servo motors instead of hydraulic systems. The primary working process is as follows:

• Feeding: Plastic pellets are fed into the heating zone and heated to a molten state.
• Plasticization and Injection: The servo motor drives the injection screw to rotate, heating the plastic and injecting it into the mold.
• Mold Closing: The servo motor precisely controls the mold closing process, maintaining the required injection pressure.
• Cooling and Solidification: The cooling system quickly solidifies the injected plastic part.
• Ejection: The mold opens, and the ejection system removes the molded plastic part.

Technical Highlights:

• Energy Closed-Loop Control: All-electric injection molding machines can recover motor regenerative energy during the holding phase, with some models recovering up to 30% of energy (e.g., Engel e-motion series).
• Zero Oil Design: All-electric models do not require a hydraulic oil system, reducing the risk of oil leakage and pollution, while significantly lowering maintenance costs. In some case studies, annual maintenance costs have dropped from 120,000 RMB to 35,000 RMB.
• The high precision and fast response of the servo motor-driven system allow all-electric injection molding machines to complete high-quality molding tasks in a shorter cycle time.

Core Components of All-Electric Injection Molding Machines

• Servo Motor System: The core drive system, using servo motors to precisely control all movements of the machine, minimizing energy loss and improving response speed.
• Control System: An integrated digital control system that monitors the production process in real-time, adjusting parameters to ensure precision.
• Injection Unit: Composed of an injection screw and heating barrel, responsible for heating and injecting the plastic into the mold.
• Mold Clamping Unit: Composed of servo motors and mechanical components, ensuring mold closing and bearing the injection pressure.
• Cooling System: Quickly cools the plastic part to solidify it using cooling channels or air cooling systems.
• Ejection Mechanism: Removes the molded plastic part from the mold through mechanical or pneumatic means.

Advantages of All-Electric Injection Molding Machines

You might wonder why all-electric injection molding machines are worth the higher cost compared to hydraulic machines. We can evaluate their value from several perspectives:

1. Significant Energy Efficiency Improvement: All-electric injection molding machines can save 30%–70% in energy. This is because the servo motors consume power only when needed for movement, unlike hydraulic systems, which require the continuous operation of hydraulic pumps even when idle.
2. Precision and Repeatability: Thanks to the high responsiveness and position feedback mechanism of the servo control system, all-electric machines can achieve repeatability as high as ±0.01 mm. This makes them especially suitable for industries that demand high precision, such as electronics, medical devices, and optics.
3. Reduced Maintenance Requirements: Without the need for hydraulic oil, there is no risk of oil leaks, no contamination from hydraulic fluid, and no need to replace hydraulic components. This leads to significantly lower maintenance frequency and costs.
4. Shorter Cycle Times: The fast response time of electric drives allows for a reduction in the overall molding cycle by 10%–30%, which improves output efficiency.
5. Environmental and Workplace Improvements: With zero oil contamination, low noise, and no unpleasant odors, all-electric injection molding machines not only improve the working environment but also make it easier to obtain certifications such as ISO 14001 for environmental management.

Disadvantages of All-Electric Injection Molding Machines

Of course, no technology is without its challenges. Here are some of the potential difficulties when using all-electric injection molding machines:

1. Higher Initial Investment Cost: Compared to hydraulic machines of the same tonnage, the initial purchase cost of an all-electric machine is 20%–40% higher, which can be a barrier for small and medium-sized enterprises or projects with limited budgets.
2. Not Suitable for High-Speed, Thick-Walled Parts: While the injection speed and pressure of all-electric machines are fast, their power output is relatively limited compared to hydraulic systems. This makes them less suitable for high-speed, thick-walled, or large parts.
3. Higher Technical Maintenance Requirements: The precision components, such as the servo control system and encoders, require operators and maintenance personnel with higher skill levels. Experienced electrical engineers are needed to handle the maintenance and troubleshooting of these advanced components.
4. Higher Component Replacement Costs: Key components such as motors and drives are often more expensive to replace than traditional hydraulic components, which can lead to higher repair costs in the event of failure.

Price of All-Electric Injection Molding Machines

The price range for all-electric injection molding machines varies depending on the brand, specifications, and features:

• Small Models (Clamping Force: 25~100 tons): Priced between 100,000 to 500,000 RMB.
• Medium Models (Clamping Force: 100~500 tons): Priced between 500,000 to 1.5 million RMB.
• Large Models (Clamping Force: 500~2500 tons): Prices can reach 1.5 million to 5 million RMB or higher.

Energy Consumption of All-Electric Injection Molding Machines

All-electric injection molding machines have significantly lower energy consumption compared to traditional hydraulic machines, especially in applications with short molding cycles or high precision requirements. The energy consumption varies based on the model, operating conditions, and production cycle, and is approximately as follows:

• Small Models: Consume 5 to 15 kWh per hour.
• Medium Models: Consume 15 to 50 kWh per hour.
• Large Models: Consume 50 to 150 kWh per hour.

How Long Do All-Electric Injection Molding Machines Last?

The lifespan of an all-electric injection molding machine depends on various factors, such as maintenance, operating environment, and the durability of key components. Below are the typical lifespans and maintenance cycles for key components:

Key Component Lifespan

Overall Lifespan: With proper maintenance, all-electric machines can last 15-20 years, but electronic components like PLCs should be replaced every 8-10 years.

Leading Domestic and International Brands of All-Electric Injection Molding Machines

There are several reputable brands in the market, each with its unique features suited to different application needs. Some of the more well-known manufacturers are as follows (based on their technical approaches):

• Top Tier: Precision Control Leaders
  • FANUC (Japan): Known for its self-adjusting AI system, enabling injection speeds up to 800mm/s (the fastest in the world).
  • Arburg (Germany): Famous for its patented Allrounder series, capable of switching production formulas in less than 0.1 seconds.
• Second Tier: Cost-Performance Benchmarks
  • Haitian (China): The Mars series uses dual-servo drives, offering performance similar to Japanese brands, but 30% cheaper.
  • LS Mtron (South Korea): Popular in Southeast Asia, with an MTBF (mean time between failures) of 18,000 hours, known for durability.
• Third Tier: Niche Market Specialists
  • Engel (Austria): Specializes in medical-grade machines, FDA-certified all-electric models.
  • Milacron (USA): Focuses on automotive lightweighting, supporting carbon-fiber-reinforced plastic molding.

Advantages of Domestic All-Electric Injection Molding Machines Over Foreign Brands

Domestic all-electric injection molding machines have unique advantages over foreign brands, especially in terms of cost, technical adaptability, and market demand. Some key advantages include:

• Price Competitiveness: Domestic all-electric injection molding machines are typically 30%-50% cheaper than international brands due to lower production costs and increasingly mature manufacturing technology.
• Market Adaptability: Domestic manufacturers design and produce all-electric machines that cater to specific needs in the Chinese market.
• Customization and Flexibility: Domestic manufacturers can offer customized solutions based on specific customer needs, adjusting machine configurations as needed.
• Diverse Applications: Domestic machines are tailored for various industries in China, such as automotive, home appliances, medical, and packaging.
• Service and After-Sales Support: Domestic manufacturers are often better equipped to provide rapid response times to faults, reducing production downtime.
• Localized R&D and Innovation: Domestic manufacturers have strong independent R&D capabilities and innovate to improve machine precision, energy efficiency, and performance.
• Shorter Delivery Times: Domestic manufacturers usually have shorter delivery times, especially for customized machines.
• Energy Efficiency and Environmental Protection: Domestic manufacturers have made significant breakthroughs in energy-saving and environmental protection technologies, such as energy recovery and oil-free designs.
• Quick Technological Catch-Up: Domestic enterprises have increased R&D investment, significantly improving technical standards, particularly in servo drive control, motor technology, and smart production.
• Rising Brand Image: Domestic brands are gaining trust in Asia, Southeast Asia, Africa, and even parts of Europe due to their high cost-performance and excellent after-sales service.
• Government Support and Subsidies: The Chinese government provides strong support for technological innovation and high-end equipment manufacturing, driving technological progress.

How to Choose the Right Injection Molding Machine for Your Project?

The following decision-making process can help you select the most suitable injection molding machine:

Decision-Making Flowchart

Clarify Requirements:

• Annual Production Volume (e.g., 500,000 parts/year)
• Product Type (precision electronic parts/large automotive parts)
• Precision Requirements (e.g., wall thickness tolerance ±0.05mm)

Cost Calculation:

• Total Ownership Cost (TCO) = Machine Price + Energy Cost + Maintenance
• Investment Payback Formula: Machine Price ÷ (Annual Electricity Savings + Yield Improvement)

Technical Compatibility:

• High Precision Scenarios: Choose multi-axis drive models (e.g., Engel e-duo)
• Large Parts: Prioritize hybrid models (e.g., Toshiba EC-Servo)

Summary and Selection Strategy

When selecting an all-electric injection molding machine, enterprises need to consider the following factors:

Selection Decision Formula:

All-Electric Suitability Index = (Precision Requirement × 0.4 + Energy Saving Requirement × 0.3 + Cleanliness Requirement × 0.3) - (Tonnage Factor × 0.5 + Budget Factor × 0.5)

For companies pursuing high precision, energy efficiency, cleanliness, and automation, all-electric injection molding machines are undoubtedly the future. With advancements in permanent magnet synchronous motors (efficiency increased to IE5 level) and silicon carbide power modules (response speed increased by 20%), all-electric injection molding machines may eventually break the 1000-ton application barrier, further expanding their application scope.

Future Outlook: Intelligence and Connectivity

With advancements in artificial intelligence, big data, and the Internet of Things (IoT), all-electric injection molding machines are set to undergo more intelligent upgrades. These machines will no longer just perform production tasks; they will have the ability to autonomously learn, optimize the production process, and predict failures. These technologies not only enhance production efficiency but also provide companies with more data support and decision-making capabilities.

At Sunbun , we have multiple all-electric injection molding machines, and our engineers are always ready to assist you with any questions. If you are interested in this article, please feel free to contact us. We are happy to provide you with a quote for all-electric injection molding machines.