High-Precision FHG Series Plastic Injection Molding Machine from China Suppliers and Factory - Efficient & Reliable
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Injection Unit
Injection Unit — Overview
Injection Unit — Detail View 1
Injection Unit — Detail View 2
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Frequently Asked Questions
Q
What is an injection unit in an injection molding machine?
A
The injection unit is the core component responsible for melting raw plastic material and injecting it under high pressure into the mold cavity. It typically consists of a hopper, barrel, screw, and nozzle working together to deliver precise shot volumes.
Q
What are the key performance indicators of an injection unit?
A
Key indicators include injection pressure, injection speed, shot weight capacity, screw diameter, plasticizing capacity, and screw L/D ratio. These parameters determine the range of materials and part sizes the machine can process effectively.
Q
How does the screw design affect injection unit performance?
A
The screw geometry — including compression ratio, flight depth, and pitch — directly influences melt homogeneity, plasticizing efficiency, and shear heat generation. Specialized screw designs are available for different materials such as PVC, PET, or engineering resins.
Q
What materials can the injection unit process?
A
Modern injection units are designed to process a wide range of thermoplastic materials, including commodity plastics (PP, PE, ABS), engineering plastics (PA, PC, POM), and high-performance resins (PEEK, PPS). Material-specific screw and barrel configurations ensure optimal processing.
Q
How is injection pressure controlled in the injection unit?
A
Injection pressure is controlled through the hydraulic or servo-electric drive system. Modern machines use closed-loop control with real-time feedback sensors to maintain consistent pressure profiles throughout the injection and packing phases, ensuring dimensional accuracy and part quality.
Q
How should the injection unit be maintained for long-term reliability?
A
Regular maintenance includes purging the barrel when changing materials, inspecting and replacing worn screw and barrel components, checking nozzle tip conditions, lubricating moving parts, and verifying temperature sensor calibration. Following a preventive maintenance schedule significantly extends the service life of the injection unit.