What are the common malfunctions and repair methods for two-color injection molding machines?

A two-color injection molding machine is an advanced plastic molding equipment that can inject two colors or two materials simultaneously. It is widely used in electronic products, household goods, automotive parts, and other fields. Compared with single-color injection molding machines, two-color injection molding machines have significant advantages in production efficiency and product diversity.
However, due to its complex structure and precise operation, various malfunctions may occur during operation. Understanding these common faults and their repair methods is crucial for ensuring stable production and extending equipment life.

1. Structural Characteristics of Two-Color Injection Molding Machines
A two-color injection molding machine mainly consists of the following parts:

Injection System
Includes the main barrel, screw, heating coil, and injection device, used to heat, plasticize, and inject the two plastic materials into the mold separately.

Clamping System
Responsible for clamping the mold, ensuring airtightness and product accuracy during the injection process.

Rotating/Turning Mechanism
Secondary injection usually requires the mold to rotate or turn to adjust the position of the first injected product to the second injection position.

Hydraulic System
Provides the power required for injection, clamping, ejection, and other actions.

Control System
Includes a PLC controller and touch screen, enabling the setting and monitoring of injection parameters.

The complex structure makes two-color injection molding machines prone to various problems during operation, especially the rotating mechanism and dual injection system, which are high-failure areas.

2. Analysis of Common Faults in Two-Color Injection Molding Machines
The following are some common faults in two-color injection molding machines during the production process:

Uneven Injection
Causes: Unstable temperature, screw wear, barrel blockage, or poor material flow.
Effects: Uneven color layering, bubbles, or short shots in the product.
Repair methods: Clean the barrel, replace the worn screw, adjust the heating temperature and injection pressure.

Rotating Mold Unable to Position
Causes: Insufficient hydraulic pressure in the rotating mechanism or control system failure.
Effects: Inaccurate secondary injection, resulting in color deviation or overflow in the product.
Repair methods: Check the hydraulic system pressure, clean the rotating mechanism guide rails, and replace the control solenoid valve.

Uneven Ejection
Causes: Ejector pin or ejection mechanism jammed, insufficient hydraulic pressure.
Effects: Incomplete product ejection, affecting production efficiency and product integrity. Repair Method: Clean the ejection mechanism, replace the hydraulic oil, and check the wear of the ejector pins.

Hydraulic System Abnormalities
Causes: Hydraulic oil contamination, excessive oil temperature, oil pump or valve failure.
Impact: Reduced injection speed and mold closing speed, unstable production.
Repair Method: Replace the hydraulic oil, clean the filter screen, and check the oil pump and valves.

Control System Alarm or Failure to Start
Causes: PLC or touchscreen failure, sensor damage, poor circuit contact.
Impact: The equipment cannot operate normally.
Repair Method: Check the sensors, troubleshoot the circuits, and replace the PLC module or touchscreen.

3. Two-Color Injection Molding Machine Troubleshooting Table
The table below summarizes common faults, inspection methods, and corresponding repair solutions for two-color injection molding machines, facilitating quick problem identification for operators:

4. Preventive Maintenance and Operation Suggestions for Two-Color Injection Molding Machines
Regularly clean the barrel and screw
Prevent the accumulation of plastic residue and impurities to ensure uniform injection.

Regularly replace the hydraulic oil
Ensure stable hydraulic system pressure and extend the lifespan of the oil pump and valves.

Check the rotating mechanism and ejection mechanism
Lubricate the guide rails and bearings to prevent jamming and inaccurate positioning.

Regularly calibrate the temperature control system
Ensure stable injection temperature and mold temperature to prevent product defects.

Keep the control system wiring clean
Avoid poor contact or short circuits that may cause equipment alarms or shutdowns.

Train operators
Familiarize them with the operation process and troubleshooting methods of the two-color injection molding machine to reduce human error.

Two-color injection molding machines, due to their ability to complete two-color or dual-material injection in one process, are widely used in plastic product manufacturing. However, the complex structure also brings potential fault risks. By mastering common fault types, troubleshooting methods, and repair solutions, and by performing daily maintenance and operator training, the equipment lifespan can be effectively extended and production efficiency improved.

Only by fully understanding the causes and solutions of faults can the production capacity of the two-color injection molding machine be maximized, ensuring stable product quality and bringing higher benefits to the enterprise.