China PVC Injection Molding Machine 100ton-800ton - Reliable Suppliers & Factory for High-Performance Production
01 Injection Unit
Injection Unit — View 1
Injection Unit — View 2
Injection Unit — View 3
Frequently Asked Questions
Q1
What is the function of the injection unit in an injection molding machine?
The injection unit is responsible for melting plastic material and injecting it into the mold cavity under high pressure. It consists of a hopper, barrel, screw, and nozzle, working together to ensure consistent and precise material delivery during each molding cycle.
Q2
What materials can the injection unit process?
Modern injection units are designed to handle a wide range of thermoplastic and thermosetting materials, including PP, PE, ABS, PVC, nylon, and engineering-grade polymers. The screw and barrel design can be customized based on the specific material requirements.
Q3
How does injection pressure affect the molding quality?
Injection pressure directly impacts the filling speed, part density, and surface finish. Insufficient pressure can lead to short shots or sink marks, while excessive pressure may cause flash or residual stress in the finished part. Precise control of injection pressure is critical for consistent product quality.
Q4
What maintenance is required for the injection unit?
Regular maintenance of the injection unit includes cleaning the screw and barrel to prevent material degradation, inspecting the check ring and nozzle for wear, lubricating moving components, and verifying temperature sensor accuracy. Scheduled preventive maintenance helps extend service life and maintain production efficiency.
Q5
How is the injection unit size selected for a specific application?
The injection unit size is determined by the shot weight, injection rate, and plasticizing capacity required for the application. Engineers evaluate part weight, wall thickness, material flow properties, and cycle time to select the appropriate screw diameter and injection unit specification.
Q6
What are the key differences between single-stage and two-stage injection units?
A single-stage injection unit uses a reciprocating screw to both plasticize and inject material in the same component, making it compact and cost-effective for standard applications. A two-stage unit separates the plasticizing and injection functions, offering greater shot consistency, higher injection speeds, and better suitability for precision or high-volume production.