The Vietnamese plastic industry is experiencing one of the highest growth rates in the economy, second only to telecommunications and textiles due to its large market and the reception of numerous new opportunities. Plastic products are widely used in daily life, including molded plastic products. Plastic manufacturing plants are continuously investing in advanced plastic molding machinery technology to meet both domestic and export market demands. One of the most significant investments in this regard is the installation of variable frequency drives for plastic molding machines, aimed at energy savings and overcoming various limitations associated with direct startup of the system.

1. Structure and Operating Principle of Plastic Molding Machine

Plastic molding machines are commonly used in injection molding technology lines. These machines play a role in maintaining a fixed mold during the process of injecting molten plastic under pressure into the mold cavity to fill it, and then opening the mold after the product has cooled down. The resulting product is then ejected through the core system.

A plastic molding machine consists of the following components:

• Plastic Injection System: including material feeding unit, heating system, screw, and other transmission mechanisms.
• Mold System: main mold, mold base, mold support, and nozzle.
• Control Electrical Cabinet.

The operation cycle of a plastic molding machine consists of 4 stages:

• Mold Closing Stage
• Injection Stage
• Cooling Stage
• Mold Opening Stage

Firstly, the raw material is placed in a hopper, heated by heating rods to an appropriate temperature, and transformed into a molten state. Then, the molten plastic is fed forward through a rotating screw, which also retracts to create space at the front of the nozzle for the plastic to flow in. Using the non-rotating pressure of the screw, the molten plastic is injected into the mold.

After the mold cavity is filled with plastic, the cooling system transforms the molten plastic into a solid state to shape the product inside the mold. Next, the movable mold clamp will open the mold by a predetermined distance, pushing the product out using the ejection mechanism of the machine.

2. Why Installing a VFD for Plastic Molding Machine Saves Energy

In plastic molding factories, hydraulic plastic molding machines are the largest electricity consumers, accounting for up to 80% of the total electricity consumption of the entire factory. How to reduce electricity consumption is a challenging question for plastic industry businesses, especially those using older technology machinery.

Hydraulic plastic molding machines operate in a closed-loop cycle consisting of key stages: mold closing, material injection, pressure molding, cooling, mold opening, and product ejection. Each stage requires different pressure, flow rates, and time.

2.1. Challenges of Using Traditional Hydraulic Plastic Molding Machines

Traditional hydraulic plastic molding machines use three-phase oil pump motors that continuously run at a fixed 100% power level in all stages.

The constant 100% power operation of the oil pump throughout all stages results in significant power wastage, especially during stages that require low flow rates and pressures (such as the cooling stage).

The system operates unstably, frequently encountering errors and requiring machine stops for troubleshooting. This leads to material loss, reduced productivity, and disruption to production schedules. Additionally, the system’s equipment and oil lifespan are also compromised.

2.2. DAT’s Solution for Up to 80% Energy Savings in Hydraulic Plastic Molding

2.2.1. GD350A VFD + PLC Card (integrated in the VFD)

Replacing the existing servo motor driver with the GD350A VFD + PLC Card solution retains the current servo motor. This solution offers superior advantages.

Advantages of the Solution:

• Quick troubleshooting and reduced machine downtime
• Lower investment costs for customers

Achieved Results:

• 24/7 technical support service for the entire plastic molding machine system.
• Stable and efficient system operation equivalent to the previous Japanese-made driver.
• Retention of the existing servo motor.
• Robust and user-friendly operational system.

2.2.2. MH800 Hydraulic Servo System

The MH800 hydraulic servo system consists of: 1 MH800 servo motor, 1 servo controller (Driver), 1 hydraulic pump head, and 1 pressure sensor mounted at the pump outlet.

• Control Principle:

During operation, the pressure sensor continuously measures the oil pressure signal and sends feedback to the servo control unit to adjust the pump motor speed according to the actual pressure and flow requirements at each stage.

• Solution Benefits:

Significantly reduces energy consumption to the lowest level, enabling businesses to save from 20% up to 80% of the total energy used in operating hydraulic plastic molding systems. Additionally, it helps reduce maximum machine operating frequency, extending the motor’s lifespan.

See more about the Solution for Saving Up to 80% Electricity with MH800 Hydraulic Servo System for Plastic Molding Machines

3. Benefits of Installing VFD for Industrial Plastic Molding Machines

In addition to the energy-saving benefits mentioned above, installing VFDs for plastic molding machines provides investors with the following advantages:

Increased productivity and waste reduction

• Easy adjustment of motor speed for optimal machine performance.
• Reduced motor wear and consistent operation contribute to increased output.

Reduced maintenance frequency and costs

• Smooth motor startup, minimizing vibrations during operation.
• Decreased oil temperature by 5-10%, extending oil lifespan by 1.5 times.

High performance, quick response, precise control

Motor protection

• Capable of withstanding three times the rated load during overload.
• Motor overload protection and automatic speed adjustment ensure motor durability.

Easy and stable operation: The system is tidy, operates stably, and reduces machine downtime.

DAT Group is a leading supplier of products and solutions in the Vietnamese market for automation, solar energy – energy storage, elevator control, and UPS. With over 17 years of development and an established value ecosystem, DAT has gained trust and collaboration from more than 10,000 customers and partners nationwide.

DAT doesn’t just provide products; it instills confidence through intelligent solutions, dedicated support services, and long-term warranty policies, all aimed at bringing substantial benefits and high efficiency to customers’ investments. With the experience and specialized capabilities of a reputable top-tier system and solution provider, DAT consistently assists customers in overcoming challenges and contributes significantly to their success.

Contact DAT through the toll-free hotline 1800 6567 to find the most effective solution for your business goals.