Injection molded products

Injection molded products are plastic items manufactured through the injection molding process. The core principle is to inject molten plastic raw materials into a closed mold, which then solidifies and cools to form products of specific shapes. This process is one of the most mature and widely applied technologies in the field of plastic processing, and the products cover thousands of categories such as industry, automobiles, medical, and consumer electronics. Here is the core knowledge system:
I. What are injection molded products?
Injection molded products refer to plastic items manufactured through the injection molding process. The core steps are: heating and melting plastic pellets → injecting them into a closed mold → cooling and solidifying → removing the mold and forming the product.
This process can produce complex-structured products ranging from a few grams to several hundred kilograms, covering daily necessities (such as plastic basins, toys), industrial components (such as gears, housings), medical equipment (such as syringes, surgical trays), automotive parts (such as bumpers, interior components), etc. It is one of the most widely used plastic processing methods in the manufacturing industry.
II. Core Process Flow of Injection Molding
1. Preparatory Work (Key to Quality and Efficiency)
Equipment Debugging: Check the operation status of the injection system, clamping system, and temperature control system of the injection molding machine, and calibrate parameters such as injection volume, holding pressure, and mold temperature.
Mold Inspection: Confirm that the mold cavities have no cracks or deformations, the gate and flow channel are unobstructed, the cooling water channels are unobstructed, and the pin mechanism is flexible.
Raw Material Pre-treatment: Dry hygroscopic plastics (such as ABS, PC), avoiding water vapor causing bubbles and silver streaks in the product; Check the compatibility of the raw material grade with the product requirements (such as strength, heat resistance).
2. Core Molding Steps
Plasticization: Heat plastic pellets in the injection machine barrel (180-300℃, depending on the material), while the screw rotates and shears and mixes to form a uniform molten state.
Injection: The screw moves forward, injecting the molten plastic at high pressure (50-200MPa) into the closed mold cavity, with a filling rate of over 95% to avoid under-injection defects.
Pressure Holding: After injection, continuous pressure is applied to compensate for plastic cooling shrinkage and prevent product from developing shrinkage marks or size deviations.
Cooling: The mold is cooled with water (15-30℃), causing the plastic to solidify and take shape. The cooling time accounts for 60%-80% of the entire cycle, and it needs to be adjusted according to the wall thickness (e.g., a 1mm wall thickness requires approximately 10-15 seconds).
Demolding: After the mold is opened, the pin mechanism will push the product out, cutting off the gate and flow channel materials, completing single-piece production.
3. Process Variants: Traditional Injection Molding vs. Precision Injection Molding
Traditional Injection Molding: Suitable for ordinary daily items and industrial components, with a precision requirement of ≤±0.1mm, lower equipment cost, and suitable for mass production.
Precision Injection Molding: For high-precision products (such as medical components, optical lenses), the precision can reach ±0.01mm, requiring a precise temperature control and pressure feedback system, with process parameter control accuracy reaching ±1%.