Injection molding machines require high precision, energy efficiency, and dynamic response for optimal production. Traditional hydraulic systems with induction motors suffer from high energy loss and poor controllability. The integration of Permanent Magnet Synchronous Motors (PMSM) with electro-hydraulic servo systems provides a superior solution, offering:
• Higher energy efficiency (up to 30-50% savings)
• Precise speed and torque control
• Reduced noise and heat generation
• Longer service life with minimal maintenance
This document outlines the design, control strategy, and benefits of using PMSM in electro-hydraulic servo injection molding machines.
The proposed system consists of:
(1) PMSM-Driven Servo Pump Unit
• PMSM Specifications:
♦ Rated Power: 15-200 kW (depending on machine tonnage)
♦ Speed Range: 0-3000 RPM (with smooth low-speed operation)
♦ Efficiency: >95% (IE4/IE5 class)
♦ Cooling: Liquid-cooled (for high-duty cycles)
• Servo Pump:
♦ Variable Displacement Axial Piston Pump
♦ Pressure & Flow Control via PMSM Speed Regulation
(2) Electro-Hydraulic Servo Valve System
• High-response proportional valves for precise pressure/flow control.
• Closed-loop feedback (pressure sensors, encoders) for real-time adjustments.
(3) Inverter (VFD) & Motion Controller
• Vector-controlled VFD for PMSM (e.g., Siemens SINAMICS, Yaskawa GA700).
• PLC Integration (e.g., Siemens S7-1500, Beckhoff TwinCAT) for synchronized motion control.
(1) Energy Savings
• Load-proportional power consumption: Unlike fixed-speed motors, PMSM adjusts speed based on demand. (Adjustable speed motor function)
• Elimination of throttle losses: No excess fluid bypass, reducing heat generation.
• Regenerative braking: Recovers energy during deceleration.
(2) Precision & Response Speed
• Torque control accuracy: ±1% (vs. ±5% in induction motors).
• Faster dynamic response: Achieves full torque at near-zero speed.
• Stable pressure control: Reduces part defects (e.g., sink marks, flashes).
(3) Noise & Heat Reduction
• Lower vibration & noise (<70 dB) due to smooth torque output.
• Reduced hydraulic oil temperature, extending component lifespan.
(4) Maintenance & Reliability
• Brushless design: No carbon brush wear.
• Lower thermal stress: Efficient cooling extends motor life.
(1) Closed-Loop Speed & Pressure Control
• Pressure feedback from hydraulic sensors adjusts PMSM speed in real time.
• PID-based algorithms ensure stability during injection/holding phases.
(2) Multi-Stage Motion Profiles
• Injection Phase: High-speed, high-torque operation.
• Holding Phase: Low-speed, precise pressure maintenance.
• Ejection & Mold Opening: Optimized acceleration/deceleration.
(3) Smart Energy Management
• Automatic standby mode when idle.
• Power consumption monitoring via HMI for optimization.
|
Parameter |
Before (Induction Motor + Fixed Pump) |
After (PMSM + Servo Pump) |
|
Energy Consumption |
45 kWh per cycle |
28 kWh per cycle (38% savings) |
|
Noise Level |
85 dB |
68 dB |
|
Response Time |
150 ms |
50 ms |
|
Oil Temperature |
55°C |
42°C |
Result:
ROI within 1.5 years due to energy savings.
Improved product consistency (reduced scrap rate by 15%).
✅ Why PMSM Win?
► Traditional injection molding machines use three-phase asynchronous motors coupled with fixed-displacement pumps, requiring the motor to run continuously during operation.
► By upgrading to a servo-driven oil pump system with a permanent magnet synchronous motor (PMSM), the motor only activates when needed for injection molding, thanks to its fast response and high starting torque. During material feeding and mold clamping, the main motor remains idle, achieving intermittent zero power consumption. Comparative tests show maximum energy savings of up to 85%.
► Additionally, advanced servo motor control algorithms significantly reduce noise compared to conventional machines. When equipped with a low-noise screw pump, the entire system operates below 70 decibels, enabling near-silent performance and improving the working environment.
⇒ Integration with IoT: Predictive maintenance via motor condition monitoring.
⇒ Hybrid Hydraulic-Electric Systems: Further energy savings with servo-electric clamping.
⇒ Advanced AI Control: Self-optimizing injection profiles.
The adoption of PMSM in electro-hydraulic servo injection molding machines provides:
✅ Major energy savings (30-50%)
✅ Higher precision & faster response
✅ Reduced maintenance & longer lifespan
For manufacturers seeking sustainable, high-performance solutions, PMSM-driven servo systems represent the future of injection molding technology. Would you like a customized feasibility analysis for your specific machine model?
