High-Precision FHG Series Plastic Injection Molding Machine from China Suppliers and Factory - FUHONG
Injection Unit
Injection Unit
Injection Unit — Detail 01
Injection Unit — Detail 02
Frequently Asked Questions
The injection unit is the core component of an injection molding machine responsible for melting plastic material and injecting it into the mold cavity under high pressure. It typically consists of a hopper, barrel, screw, and nozzle working together to ensure precise and consistent material delivery.
The main components include the hopper (for raw material feeding), the heated barrel (for melting), the reciprocating screw (for mixing and pushing material forward), the nozzle (for directing melt into the mold), and the injection cylinder (for applying injection pressure).
Injection pressure directly influences how completely and uniformly the mold cavity is filled. Insufficient pressure can cause short shots or sink marks, while excessive pressure may lead to flash, warping, or internal stress in the finished part. Proper pressure calibration is essential for achieving consistent, high-quality results.
Injection units are compatible with a wide range of thermoplastic materials including PP, PE, ABS, PC, PA (Nylon), POM, PET, and many engineering-grade polymers. Specialized units can also handle thermosets, elastomers, and fiber-reinforced composites depending on screw and barrel configurations.
Regular maintenance includes purging the barrel when changing materials, inspecting and replacing worn screw and barrel components, checking nozzle tip condition, lubricating moving parts, and monitoring heater bands and temperature sensors. Scheduled preventive maintenance helps extend service life and ensures production consistency.
A single-stage injection unit uses one reciprocating screw for both plasticizing and injection. A two-stage unit separates these functions — a screw handles plasticizing while a plunger performs the injection. Two-stage systems offer more consistent shot volumes and are preferred for large-tonnage or precision applications.