Hello everyone! I'm Jason (you can also call me Xiaosu) from In-saiL . In the last issue, we talked about the ultrasonic/heating staking threaded inserts. I believe that everyone has a certain understanding of ultrasonic/heating staking threaded inserts. In the last issue, we mentioned that this type of nut is installation in plastics by ultrasonic/heating staking. Then we should design the product. What aspects should be considered?

Today I will give you a brief explanation of some design ideas for threaded inserts. We know that in many plastic parts, in order to install and connect, it is often necessary to place some metal parts or other materials in the plastic parts. These parts , Collectively referred to as inserts in plastic products. The picture shows the typical shapes of some inserts:

(Plastic inserts not only refer to the embedded nuts, plastic embedded screws and plastic embedded shafts produced by our company, but also all other parts embedded in plastics.)

First of all, we have to understand a few points.

• The first one is what are the notable features of the insert?

Inserts are mostly made of metal, which can increase the strength and rigidity of the entire plastic part or a certain part, such as the metal bone rod inserts used on helmets, handles, and suitcases.

The connection strength can be improved. The strength of the plastic is very low. If you want to connect two plastic parts together, if you only use screws to connect, the strength will be affected, and the threaded insert is embedded in the plastic part in advance. This can greatly increase the strength of the connection, effectively improve the torsion resistance and durability.

Plastic is a very good insulator, and some metal sheets, wires, boards, etc. are placed in the plastic parts, which makes it very useful in electronics, electrical appliances, and power components. For example, our common laptops, mobile phones, etc., will see the figure with inserts.

The hardness of plastics is low, and the ability to resist external forces is weak. Placing a suitable metal insert at the position that needs to improve the hardness and wear resistance will effectively improve the hardness and wear resistance of the insert.

• The second is what are the common materials for inserts?

There are many materials for making inserts. Both metal and non-metallic materials can be used for making inserts, but most of them are made of metal materials. Commonly used metal materials are Steel (SUS303, SUS304, etc.), Brass (commonly C3604),Aluminum (AL) and so on. Among them, brass alloy has high mechanical strength, does not rust, and is easy to process. It is a common material for making inserts; however, the coefficient of thermal expansion of brass and plastic is quite different, and the bonding firmness is poor; while aluminum has the largest coefficient of thermal expansion, and The combination of plastic is the strongest, and it is also a common material, but the strength is lower. So on the whole, brass is better. If you want to make the connection strength between plastic parts higher, the choice of material is better than brass.

• The third is what are the characteristics of our insert design?

1)Knurling; common knurled herringbone knurling, reverse twill knurling, diamond knurling, arc (crescent) knurling, barbed knurling, straight grain (vertical stripe) knurling, inside and outside Tooth knurling and so on. (As shown below)

2)Chamfering; in order to facilitate the installation, we will add a chamfer at the front end of the insert when designing the insert product, so that it can play a role of fixed alignment during installation and increase the installation efficiency.

3) Guide section; the role of the guide section is also to facilitate installation. (As shown below)

4) Groove: In order to make the insert and the plastic part be tightly combined, the surface of the insert should be processed with grooves. During heating installation, the plastic softens and fits tightly on the groove surface. When the insert is buried, stop heating . The plastic is cooled and hardened, and the groove design can greatly increase the friction, so that the insert is not easy to be pulled out during use, and does not rotate. (As shown below)

Today’s sharing comes to an end for the time being, we will continue to upload some things we have to say about plastic inserts, please look forward to it. If you need more detailed introduction or information, you can contact us. There is my contact information at the bottom of the website. Welcome to inquire!