Parting Surface Design In Injection Mold Design

In order to meet the needs of demolding of plastic parts and condensing materials in the gate system and the need for insert installation, the cavity of the injection mold can be appropriately divided into two or more parts. These contact surfaces that can be separated are called parting surfaces. . In the case of poor mold manufacturing and insufficient clamping force, the molten plastic in the injection mold will be extruded through the parting surface to form a thicker burr. Despite the modifications, significant traces remain. There are many types of parting surfaces, the common ones are horizontal parting surfaces, stepped parting surfaces, oblique parting surfaces and special parting surfaces. The parting surface is usually flat, but sometimes it is necessary to use curved and stepped surfaces to facilitate demolding.

The quality of the separation surface in the injection mold has a great influence on the quality of the plastic part and the processing performance. Therefore, the following principles should be comprehensively considered when selecting the parting surface of an injection mold:

1. Convenient demolding of plastic parts. Not only is the parting surface required to prevent the plastic parts from getting stuck in the cavity and cannot be taken out, but it is also required that the plastic parts stay on the side of the moving mold when the mold is opened, thereby facilitating the design of the demolding mechanism. Therefore, the main mold core is usually installed on the side of the mobile mold, the plastic parts are shrunk and wrapped on the main mold core, so that the cavity can be installed on the side of the fixed mold. If there are fixed inserts on the plastic part or there are no holes in the plastic part, you can design the cavity on the side of the moving mold for the plastic part by adhering the complex shape to the mold cavity. After opening the mold, it can stay on the side of the moving mold.

2. The structure of the injection mold is as simple as possible: if the shape of the plastic part is special, and the parting surface is designed to be flat, the bottom of the cavity will not be easy to process. If the parting surface is designed as an inclined surface or a curved surface so that the bottom of the cavity becomes a horizontal plane, it is easy to process.

3. The gas in the cavity can be smoothly discharged: the main discharge method is to set a discharge groove on the parting surface. Therefore, the separation surface should be at the end of the melt flow. If the parting surface is too close to the gate, it is easy to cause poor ventilation.

4. The quality of plastic parts can be guaranteed: the position of the parting surface should be conducive to ensuring the coaxiality of the plastic parts, and the dimensional accuracy of the plastic parts should be guaranteed, so as to ensure the quality of the plastic parts.

5. Will not damage the appearance of the product.

6. The equipment can be used fully and reasonably, and the parting surface should avoid core pulling for a long distance: the lateral core pulling of a typical injection mold is achieved through the mold opening movement. When the core is pulled by the mold core pulling mechanism, the distance to complete the core pulling is limited to a limited opening stroke. Therefore, for plastic parts with holes or grooves in two mutually perpendicular directions, pulling the core over a long distance should be avoided.