1. First, what is insert injection molding?
plastic injection mold
Insert refers to the mold accessories used for inlaying in the mold core. The inserts can be square, round, and sheet type. Like all mold accessories, the requirements for precision are also very high. Generally, there is no finished product and it is customized according to the needs of the mold.
Type of insert: insert pin, insert block, insert column, insert ring, etc;
Material: SKD61, SKH51, ASP23, SKD11, etc., or the same as the corresponding mold core material;
Hardness: above 50HRC;
Standard precision: ± 0.01mm, depending on the specific mold precision requirements.
2.So the question is, under what circumstances do you need to do insert injection molding?
2.1 Save mold materials
As we all know, when sizing the mold, it is a piece of steel with regular shape. However, the material of the front and rear molds is determined by the highest point. Therefore, whether it is the front mold or the rear mold, if a certain place is higher than other places, the height of the mold core can be reduced by making inserts. In this way, the sizing of the mold core does not need to be so high, so as to save mold materials.
2.2 Convenient mold modification
Where the mold is often modified, it can be disassembled to make inserts. In the future, only the inserts need to be replaced when the mold is modified, and even several spare parts of inserts can be made for replacement when the mold is opened, so that the mold can be modified easily. For example, some ODM manufacturers have the same product appearance, and only need to change the LOGO to become a product of another brand. At this time, the LOGO piece on the mold can be disassembled to make an insert, so there is no need to reopen a set of molds.
2.3 It is conducive to the exhaust of the mold
Mold exhaust is very important. If the exhaust is not good, air will be trapped in the mold cavity, especially in the deep bone position. During injection molding, products are prone to bubbles or shrinkage, lack of glue, white or black spots and other undesirable phenomena. Therefore, inserts can be added at the place where the mold needs to exhaust, and the fitting gap of inserts can be used for exhaust.
2.4 Convenient tooling
We know that in some deep positions of injection mold, it is difficult for the tool to cut. If EDM is used, it is known that EDM is the slowest and the processing efficiency is too low. Therefore, inserts are generally selected here to reduce the processing difficulty and facilitate the exhaust. There is also the dart in the deep bone position. It is not convenient to dart in the places where the need for mold production must be saved, but it is more convenient to open inserts in these places and remove them separately.
2.5 Increase the service life of the mold
In general, the places where the insert of the mold needs to be designed are often the places that are easy to be damaged, such as some places where the thin steel of the sharp steel can be replaced once the insert is damaged, so as to extend the service life of the mold.
2.6Temperature of conduction mold
In general, the mold is cooled through the design of water circuit, but some places can not be designed or can not be reached by water circuit, and these places can be cooled by making inserts. Of course, materials with good thermal conductivity must be selected for the inserts, such as beryllium copper.
3. Of course, there are some defects in the mold inserts, such as the following:
1. Increase the difficulty in mold assembly;
2. Glue overflow flash is easy to occur around the insert;
3. Sometimes the die design and processing cost will be increased when the die is made of inlaid structure, thus increasing the cost;
4. Too many inlaying structures will affect the design of mold cooling water path;
5. Too many inlay structures will affect the strength of the mold core.
4.Summary
The insert is a very common structure in the mold. Although it has defects, its advantages are also obvious. When designing the mold, we should judge which parts need to be inserted according to the specific product structure, and which parts can be left intact without the need to be inserted. At the same time, it should be noted that there are generally insert marks or insert lines at the places where inserts are made. The customer needs to confirm whether they can be accepted during the mold opening review.
