Classifications of plastic injection molds,Plastic injection molds are classified based on various criteria, including their design, construction, and application. Here are some common classifications of plastic injection molds:
Classifications of plastic injection molds
1. Based on Design Complexity
Single Cavity Molds
These molds produce a single plastic part per cycle.
Single-piece mold, when the single-piece plastic injection mold is opened, the movable mold and the fixed mold are distinguished, and then the plastic parts are taken out, which is called a single-piece mold, also known as a double-plate mold. It is a quite simple and basic plastic injection mold. It can be designed as a single cavity injection mold or a multi-cavity injection mold according to client’s requirements. It is a widely used plastic injection mold.
Multi-Cavity Molds
These molds have multiple identical or different cavities, allowing for the simultaneous production of multiple parts in each cycle.
Double-split plastic injection mold, the double-split surface injection mold has two parting surfaces. Compared with the single-piece exterior injection mold, the double-split injection mold adds a partially movable center plate (also called an automatic gate plate, which is equipped with gates, slides and other components and fixed mold parts) in the fixed mold parts. Therefore, it is also known as a three-plate type (moving platen, center plate, fixed platen) injection mold, which is often used for spotting.
Single-cavity or multi-cavity injection mold When the mold is opened, the center plate is separated from the fixed plate by a certain distance on the fixed column guide column, and then the casting system aggregate is taken out between the two templates. Two parts molding molds have complex structures, so have a high production costs, and difficult parts processing, and are generally not used for molding large or extra-large plastic products production.
Family Molds
Family molds have multiple cavities that produce different parts or components in a single cycle. They are used when several related parts are needed for assembly.
2. Based on Runner System
Cold Runner Molds
These molds have a runner system that remains at room temperature. They are common for low- to medium-volume production but can generate more waste material.
Hot Runner Molds
In hot runner molds, the runner system is heated, which reduces material waste and is suitable for high-volume production. They are more complex and expensive to manufacture but can be cost-effective in the long run.
3. Based on Mold Construction
Two-Plate Molds
These molds consist of two plates that separate to eject the molded part. They are simple and cost-effective for basic parts.
Three-Plate Molds
Three-plate molds include an additional plate, which allows for the ejection of the part and runner system separately. They are used for more complex parts or when a hot runner system is used.
Stack Molds
Stack molds have multiple mold surfaces that stack vertically. They are used for high-speed production and to create thin-walled parts.
4. Based on Mold Material
Steel Molds
These molds are made from hardened steel, which is durable and suitable for high-volume production.
Aluminum Molds
Aluminum molds are less expensive and are often used for low-volume production or prototyping.
Beryllium-Copper Molds
These molds have good heat conductivity and are used for high-precision molding.
5. Based on Application
Prototype Molds
These molds are used for producing prototypes and limited runs of parts for testing and validation.
Production Molds
Production molds are designed for high-volume manufacturing and are built to withstand continuous use.
Multi-Shot Molds
Multi-shot molds can produce parts with multiple materials or colors in a single cycle, such as overmolding or two-shot injection molding.
6. Based on Part Geometry
Thin-Wall Molds
These molds are designed for parts with thin walls, such as packaging containers.
Complex Shape Molds
Molds for parts with intricate or complex geometries require specialized design and construction.
7. Based on Special Features
Insert Molds
These molds allow for the insertion of pre-formed components (e.g., metal inserts) during the molding process.
Gas-Assist Molds
Gas-assist molds use gas injection to hollow out thick sections of a part, reducing material use and improving part strength.
The choice of mold type depends on factors like production volume, part complexity, material selection, and budget. Mold design and classification play a crucial role in the efficiency and quality of the plastic injection molding process.
