The structure of an injection mold is determined by the type of injection molding machine and the structural characteristics of the plastic part. Each mold consists of a moving mold and a fixed mold. The moving mold is mounted on the moving platen of the injection molding machine, while the fixed mold is mounted on the stationary platen. During injection, the moving and fixed molds close to form the gating system and cavity. When the molds separate, the plastic part or die remains on the moving mold side and is ejected by the demolding mechanism located within the moving mold. Based on the different functions of each component, an injection mold can be divided into the following parts:
1. Molding Parts
These parts give the molding material its shape, structure, and dimensions. They typically consist of cores (punches), cavity molds, threaded cores, inserts, etc.
2. Gating System
This is the channel that guides the molten plastic from the injection nozzle to the closed mold cavity. It typically consists of the main runner, branch runners, gate, and cold slug well.
3. Guiding Components
Guiding components are installed to ensure precise alignment when the moving and fixed molds close. They serve a guiding and positioning function and consist of guide pillars and guide sleeves. Some molds also have guiding components on the ejector plate to ensure smooth and reliable movement of the demolding mechanism.
4. Demolding Mechanism
This is the device that demolds the plastic part from the gating system. It has many structural forms, the most common being ejector pins, ejector tubes, ejector plates, and pneumatic ejection mechanisms. It generally consists of ejector pins, return pins, springs, ejector pin fixing plates, ejector plates (ejector rings), and ejector plate guide pillars/sleeves.
5. Mold Temperature Control System
To meet the temperature requirements of the injection molding process, a mold temperature control system with heating rods is needed to regulate the mold temperature.
6. Venting System
To facilitate the expulsion of gas from the mold cavity, venting grooves are often provided at the mold parting surface and the mating points of inserts and bushings.
7. Other structural parts
These refer to parts designed to meet the structural requirements of the mold (such as: fixed plates, moving/fixed templates, support columns, support plates, and connecting screws, etc.).