What Are the Classifications of Injection Moldings?

Injection moldings are tools that give plastic products complete structure and precise dimensions. They are the core pillar of cosmetic packaging materials, especially plastic packaging materials, and also the tool for producing plastic products. This article shares several types of injection moldings.

Plastic molds give plastic products complete configuration and precise dimensions. They are tools used in conjunction with plastic molding machines in the plastic processing industry. According to different molding methods, they can be divided into different types of molds. With the cooperation of various systems or auxiliary devices in the mold, specific shape, size, function, and quality of industrial parts can be produced through high-temperature liquefaction filling of plastic particles into the mold cavity. Common mold classifications can be divided into the following categories:

Single Parting Surface Injection Molding

When the mold is opened, the moving and fixed molds are separated, so that the plastic parts can be taken out. This is called a single parting surface mold, also known as a two-plate mold. It is the simplest and most basic form of injection molding. It can be designed as a single-cavity injection molding or a multi-cavity injection molding as needed. It is the most widely used injection mold.

Double Parting Surface Injection Molding

The fixed mold part of the double parting surface injection molding adds an intermediate plate that can move locally. The double parting surface injection mold has two parting surfaces, so it is also called a three-plate injection molding. It is often used in single-cavity or multi-cavity injection molding with point gate feeding. When the mold is opened, the intermediate plate and the fixed mold plate are separated by a certain distance on the guide pillar, so that the condensed liquid in the injection system can be removed from between the two molds.

Injection Molding with Lateral Parting and Core-Pulling Mechanism

The inclined section of the ejector pin fixed on thefixed mold plate forces the slide to move outward. When the plastic part has a side hole or side groove, the push rod of the stripping mechanism pushes the push plate, allowing the plastic part to peel off from the core, which needs to be molded using a core that can be moved laterally or a slider.

Injection Molding with Movable Molding Parts

The injection molding requires movable molding parts. Due to the special structure of some plastic parts, the molding parts can be moved out of the mold together with the plastic parts during the demolding process.

Automatic Unscrewing Injection Molding

For plastic parts with screws, when automatic demolding is required, a rotatable screw mandrel or ring can be set on the mold using the opening action or rotating mechanism of the injection molding machine, or a special transmission device can be used to drive the screw mandrel or screw-shaped ring to rotate and push the plastic part out of the mold.

Insulated and Heated Nozzle Injection Molding

The insulated and heated nozzle injection mold refers to a mold without a runner, which means that there is no condensate in the gating system when the plastic parts are taken out. It keeps the plastic in a molten state between the nozzle of the injection molding machine and the mold cavity, which is called insulated runner injection mold or hot runner injection mold.

Right-angle Injection Molding

Different from other injection moldings, the right-angle injection molding is only suitable for corner injection machines. The feeding direction of this mold is perpendicular to the opening and closing direction. Its cross-sectional area is usually constant, and the main runner is located on both sides of the fixed and movable molds. The end of the main runner can be equipped with replaceable runner plugs to prevent wear and deformation of the nozzle and the entrance of the main runner.

Demolding Mechanism on Fixed Mold Injection Molding

In most injection moldings, the demolding device is installed on the side of the movable mold, which is beneficial to the operation of the ejector in the opening and closing system of the injection molding machine. However, in practical production, some plastic parts are limited by their shape, and it is better to leave them on the side of the fixed mold. Therefore, a demolding mechanism needs to be set on the side of the fixed mold.