Which errors are easy to make in the injection mold process?

2021-03-23 11:46:15 admin

Which errors are easy to make in the injection mold process?

In fact, injection mold engineering is often used to make plastic products, and the structure and size of plastic are also made into a workpiece through a technology. Therefore, the structure and quality of injection molding can directly affect the quality of the finished product, so it is easy to appear in the work of injection mold. What are the problems? Let's take a look.

1. Difficulty in gate drop

During the injection molding process, the grid gluing sleeve on the grid is easy to sag. When the mold was opened, the cracked item was damaged. In addition, operators must use copper to knock from the nozzle head, which has severely affected the loosening of production efficiency after the release. The main reason for this failure is the difference in the end of the cone hole, and the hole is marked in the circumferential direction. Secondly, the material is too soft, the small end of the taper hole is deformed or damaged after a period of time, and the curvature of the nozzle spherical surface is too small, causing the rivet head produced by the grid material. The processing difficulty standard for tapered sprue bushings should be adopted. For your own treatment, you should do it for future or special reamers. The cone is polished above Ra0.4. In addition, the grid must provide a pull rod or runner ejection mechanism.

2. Guide post damage

The guide post mainly plays a guiding and educational role in the mold to ensure that the molding surface of the core and the cavity can not collide with each other under any circumstances, and the guide post design cannot be used as a force-receiving part or a positioning part. In the following analysis of several different situations, the moving mold will have a huge impact on the lateral horizontal offset force during injection: (1) When the wall thickness of the plastic part is required and uneven, the material flow through the thick wall has a large speed, where We produce a relatively large pressure; (2) The side reaction of the plastic part is asymmetrical, such as the development of a stepped parting surface. The opposite pressure on the two sides of the mold structure is also not equal.

3. Movable template bending

When injecting molds, reverse pressure may be generated in the cavity, and many workers often do not pay attention to this, which leads to the finished product deviating from the expected result.

During injection, the molten plastic in the mold cavity produces a huge back pressure, generally 600-1000 kg/cm. Mold manufacturers sometimes do not pay attention to this problem, often change the original design size, or replace the movable template with a low-strength steel plate. There is the top material of the ejector pin on the mold. Due to the large span on both sides of the valve seat, the template will bend downward during injection molding.