Four basic knowledge points of injection mold

December 16, 2022

Four basic knowledge points of injection mold

The Auto Inner Parts Plastic Injection Mould is composed of two parts, the moving mold is installed on the moving template of the Plastic Auto Inner Parts Mold, and the fixed mold is installed on the fixed template of the Plastic Auto Inner Parts Mold. During injection molding, the moving mold and the fixed mold are closed to form the casting system and cavity, and the moving mold and the fixed mold are separated when the mold is opened to remove the plastic products.

Although the structure of the ABS Plastic Part Injection Molding may vary depending on the variety and performance of plastics, the shape and structure of plastic products, and the type of ABS Plastic Part Injection Molding, the basic structure is the same. The ABS Plastic Part Injection Molding is mainly composed of pouring system, temperature regulation system, forming parts and structural parts. Among them, the pouring system and molded parts are the parts that are in direct contact with the plastic, and change with the plastics and products, which is the most complex and the most varied part of the plastic mold, requiring the highest processing finish and precision.

The gating system refers to the part of the flow channel before the plastic enters the cavity from the nozzle, including the main channel, cold material cavities, manifolds and gates. Plastic Auto Inner Parts Mold refer to various parts that make up the shape of the product, including moving molds, fixed molds and cavities, cores, forming rods and exhaust ports.

First, the gating system
The gating system, also known as the runner system, is a set of feeding channels that lead the plastic melt from the nozzle of the injection machine to the cavity, usually consisting of the main channel, the diverter channel, the gate and the cold material cavity. It is directly related to the molding quality and production efficiency of plastic products.

1. Mainstream Road

It is a section of passage in the mold that connects the nozzle of the injector to the manifold or cavity. The top of the main channel is concave to allow for connection with the nozzle. The inlet diameter of the main channel should be slightly larger than the nozzle diameter (O.8mm) to avoid overflow and prevent blockage due to inaccurate connection between the two. The diameter of the import depends on the size of the product, generally 4-8mm. The diameter of the main channel should be expanded inward at an angle of 3° to 5° to allow the release of the runner waste.

2. Cold material cavities
It is a hole located at the end of the main channel to trap the cold material generated between injections at the end of the nozzle, thereby preventing blockage of the shunt channel or gate. If the cold material is mixed into the cavity, internal stress is easy to occur in the manufactured product. The diameter of the cold material cavity is about 8 to l0mm, and the depth is 6mm.

In order to facilitate demolding, its bottom is often borne by a demolding rod. The top of the release rod should be designed in a zigzag hook shape or a sag groove so that the main stream can be pulled out smoothly during demolding.

3. Shunt channel
It is the channel that connects the main channel and the individual cavities in a multi-slot mold. In order to fill each cavity with the melt at equal speed, the arrangement of the manifold on the mold should be symmetrical and equidistant distribution.

The shape and size of the manifold section have an impact on the flow of the plastic melt, the release of the product and the difficulty of Plastic Auto Inner Parts Mold manufacturing. If the flow is based on the same amount of material, the runner resistance in the circular section is minimal.

However, because the cylindrical runner is smaller than the surface, it is not conducive to the cooling of the divert waste, and this shunt channel must be opened on two halves of the Plastic Auto Inner Parts Mold, which is labor-intensive and easy to align. Therefore, diverters with trapezoidal or semicircular sections are often used and are set on half of the mold with a release rod.

The runner surface must be polished to reduce flow resistance and provide fast mold filling speed. The size of the runner depends on the plastic variety, the size and thickness of the product. For most thermoplastics, the width of the cross-section of the manifold is not more than 8m, and the extra large can reach 10-12m, and the extra small 2-3m. Under the premise of meeting the needs, the cross-sectional area should be reduced as much as possible to avoid increasing the diverter waste and prolonging the cooling time.

Auto Inner Parts Plastic Injection Mould