In today’s competitive manufacturing landscape, energy costs represent one of the largest operational expenses for plastic injection molding facilities. A conventional Hydraulic Injection Molding Machine runs its fixed-speed motor at full power regardless of actual load demand — a fundamentally wasteful design. The emergence ofServo Hydraulic Systems, also known as Electro-Hydraulic Servo Systems (EHSS), has fundamentally changed this equation, enabling manufacturers worldwide to slash energy consumption by40% to 80% while simultaneously improving precision and cycle times.
This guide explains exactly how servo hydraulic technology works, what components make up a high-performance servo pump set, and how to calculate the real return on investment when upgrading your Hydraulic Injection Molding Machine.
⚙1. Why Conventional Hydraulic Systems Waste Energy
A traditional Hydraulic Injection Molding machine uses aninduction motor running at constant speed (typically 1,450–1,500 RPM) coupled to a fixed-displacement or variable-displacement vane pump. During the cooling phase — which can account for 40–60% of total cycle time — the machine still consumes nearly full power because the motor never stops. This “always-on” approach generates excessive heat, increases oil degradation, and wastes electricity on a massive scale.
In a typical 8-hour production shift, a 110 kW conventional hydraulic press may operate at full load for only 30–40% of the time. The remaining 60–70% of energy is wasted during idle, pressure-hold, and cooling phases — energy that a servo hydraulic system recovers almost entirely.
A modern electro-hydraulic servo injection molding machine. The servo pump set replaces the conventional fixed-speed motor and vane pump assembly, delivering power only when and where it is needed.
⚙2. How a Servo Hydraulic System Works
A servo hydraulic system replaces the fixed-speed induction motor with a permanent magnet synchronous servo motor (PMSM) controlled by a dedicated servo drive (inverter). The servo drive continuously reads pressure and flow demand signals from the machine’s control system and adjusts motor speed in real time — from near-zero RPM during cooling to full speed during injection. The hydraulic pump (typically a high-efficiency internal gear pump or servo vane pump) is directly coupled to the servo motor shaft.
🔧The Three Core Components of a Servo Pump Set
| Component | Function | Key Specification (NVICKS ABT Series) |
|---|---|---|
| Servo Drive (ABT580) | Converts AC power to variable-frequency output; controls motor speed and torque with millisecond response | 2.2× overload capacity; deep field-weakening control; supports SPM & IPM motor algorithms |
| Servo Motor (ABT1007E) | High-torque PMSM that converts electrical energy to rotational mechanical energy with >95% efficiency | Permanent magnet synchronous; 1,000–3,000 RPM operating range; IP65 protection |
| Internal Gear Pump (VG Series) | Converts rotational energy to hydraulic flow; ultra-low noise and minimal pulsation | 8–160 cc/rev displacement; up to 25 MPa operating pressure; <65 dB(A) noise level |
The NVICKS ABT servo pump set integrates three precision-engineered components into a single, optimized package for hydraulic injection molding machines.
⚡3. Energy Savings: The Numbers Behind the Technology
The energy savings from a servo hydraulic system are not theoretical — they are measurable and verifiable. The primary mechanism is demand-responsive power delivery: the servo motor only draws the electrical power required to meet the instantaneous hydraulic demand. During the cooling phase, motor speed drops to near zero, consuming only 2–5% of rated power instead of 60–80% in a conventional system.
The following table illustrates the power consumption profile across a typical injection molding cycle:
| Cycle Phase | Duration (Typical) | Conventional System Power | Servo System Power | Energy Saved |
|---|---|---|---|---|
| Mold Closing | 2–4 s | 100% | 85–95% | 5–15% |
| Injection | 1–3 s | 100% | 90–100% | 0–10% |
| Pressure Hold | 3–8 s | 70–80% | 20–35% | 45–60% |
| Cooling | 8–25 s | 60–70% | 2–5% | 65–68% |
| Mold Opening & Ejection | 2–5 s | 100% | 80–90% | 10–20% |
A 160-ton hydraulic injection molding machine running 20 hours/day, 300 days/year at an electricity rate of $0.12/kWh can save approximately $8,000–$15,000 USD per year after installing a servo pump set — with full payback typically achieved within 18–30 months.
💡4. Additional Benefits Beyond Energy Savings
✔4.1 Improved Precision and Part Quality
Servo drives provide closed-loop pressure and flow control with response times under 10 milliseconds. This level of precision eliminates the pressure fluctuations common in conventional systems, resulting in more consistent part dimensions, reduced flash, and lower scrap rates — particularly critical for thin-wall and precision optical components.
🔇4.2 Reduced Noise and Heat Generation
Because the servo motor slows or stops during non-productive phases, noise levels drop dramatically — typically by 10–15 dB(A) compared to a constant-speed system. Lower motor speeds also mean less hydraulic oil shear heating, reducing oil temperature by 10–20°C and extending oil change intervals by 30–50%.
⏳4.3 Extended Machine and Mold Life
Smooth, controlled pressure ramps during mold closing and opening eliminate hydraulic shock — a leading cause of mold wear and machine fatigue. Manufacturers report a 20–40% reduction in mold maintenance costs after switching to servo hydraulic control.
🔄4.4 Drop-In Retrofit Compatibility
A major advantage of servo pump sets is their drop-in retrofit compatibility. The servo motor, drive, and pump assembly mount directly to the existing hydraulic tank and plumbing without structural modifications to the machine frame. Most retrofit projects are completed within one working day, minimizing production downtime.
🛠5. How to Select the Right Servo Pump Set
Selecting the correct servo pump set requires matching four key parameters to your machine’s hydraulic specifications:
- Peak Flow Rate (L/min): Determine the maximum flow demand during the injection phase. This sets the minimum pump displacement and motor speed requirement. Undersizing the pump will cause pressure drop during injection.
- Maximum System Pressure (MPa): Match the pump’s rated pressure to your machine’s relief valve setting. NVICKS VG Series pumps are rated up to 25 MPa for standard applications and up to 40 MPa for the VGH0 high-pressure series.
- Motor Power (kW): Calculate required motor power using: P (kW) = [Q (L/min) × P (MPa)] ÷ 60. Add a 15–20% safety margin. NVICKS ABT servo motors are available from 7.5 kW to 200 kW to cover the full range of injection molding tonnages.
- Communication Protocol: Ensure the servo drive supports your machine controller’s communication bus (CANopen, Modbus RTU, EtherCAT, or analog ±10V). NVICKS ABT580 drives support all major industrial protocols.
🌍6. NVICKS Servo Pump Set: Proven Performance Across 35+ Countries
NVICKS (Ningbo Vicks Intelligent Equipment Co., Ltd.) has been developing servo hydraulic solutions for over 18 years, with products deployed across 35+ countries. The ALBERT ABT servo pump set — integrating the ABT580 servo drive, ABT1007E servo motor, and VG internal gear pump — represents the culmination of this experience, co-developed with Zhejiang University’s Mechanical Control Engineering Research Institute and certified under ISO quality standards.
The ABT series is specifically engineered for the demanding duty cycles of injection molding, rubber vulcanizing, hydraulic press, and bending machine applications, with a track record of over 200,000 units delivered annually. As a National High-Tech Enterprise and “Little Giant” enterprise recognized by China’s Ministry of Industry and Information Technology, NVICKS backs every servo pump set with a comprehensive global warranty and 24-hour technical support.
Ready to reduce your energy costs by up to 80%? Contact the NVICKS engineering team for a free energy audit and servo pump set recommendation tailored to your specific injection molding machine model and production requirements.