In plastic mold design, why do some places need to be inserts?

Time:2020-10-08 11:17:30 / Popularity: / Source:

First, what is called insert?

Inserts is a mold term. It is specifically referred to as a mold fitting for inlaying in a mold. Inserts can be square, round, and sheet-shaped. Like all mold parts, precision requirements are also very high. Generally, there is no finished product, and it is customized according to needs of mold.
Types of inserts: core pin, insert block, insert rod, insert ring, etc.;
Material: SKD61, SKH51, ASP23, SKD11, etc., or same as mold material;
Hardness: 50HRC or more;
Standard accuracy: ±0.01mm, depending on specific mold accuracy requirements.

Second, when do we need to make inserts?

1, save mold material

As we all know, predetermined material of mold is some piece of steel with a relatively regular shape. However, material of front and rear molds is determined by the highest point, so whether it is front mold or rear mold, if a place is relatively high to other places, this place can reduce height of core in moulding by making insert, so that material of core in moulding does not need to be ordered to be so high, thereby saving mold material.

2, convenient to modify mold

Where mold is often modified, it can be removed to make insert. In the future, when mold is modified, it is only necessary to replace insert. Even when mold is made, more spare parts of several inserts can be replaced for replacement, so that mold can be easily modified. For example, some ODM manufacturers’ products have same appearance. Just change LOGO and become another brand's product. At this time, mold can be removed from LOGO to make insert, so that there is no need to reopen a new mold.

3, conducive to exhaust of mold

Die venting is very important. If exhaust is not good, it will be trapped in the cavity of mold. Especially deeper bone position is more likely to be trapped. Product is prone to bubbles or shrinkage, lack of material, whitening or black spots during injection molding, so that inserts can be added to the place where mold needs to be vented, and exhausted by matching gap of insert.

4, convenient mold processing

We know that some deep bones in injection mold, tool is difficult to process, such as EDM machining, we all know that EDM processing is the slowest, processing efficiency is too low. Therefore, it is generally preferred to use inserts to reduce difficulty of processing and to facilitate exhaust. There is also deep bone polishing, which is quite inconvenient to polish for place that because need to be polished because of demoulding. However, it is much more convenient to open inserts in these places and remove them separately.

5, increase life of mold

In general, where mold needs to be designed with inserts, it is often a place that is easily damaged. For example, some steel strips can be replaced once insert is damaged, thus extending service life of mold.

6, conduction mold temperature

Under normal circumstances, mold is cooled by designing waterway. However there are some places where it is impossible to design waterway or waterway can’t reach. These places can be dissipated heat through inserts. Of course, material of insert must have better thermal conductivity, such as beryllium copper.
plastic mold design 

Third, mold inserts are also defective, such as following:

1. Increase difficulty of assembling mold;
2. It is easy to produce overflow and flash around insert;
3. Mold to make mosaic structure will sometimes increase cost of plastic mold design and processing, thereby increasing costs;
4. Too many inlay structures will affect design of mold cooling waterway;
5. Too many inlay structures will affect strength of core in moulding.

Fourth, summary

Insert is already a very common structure on mold. Although it is defective, advantage is also obvious. When designing mold, it should be judged according to specific product structure, where inserts need to be made, and where originals can be left without need for inserts. At the same time, it should be noted that there are generally inlay marks or insert lines in the place where inserts are made. It is necessary for customer to confirm whether it is acceptable when have mold review meeting.

Go To Top