What You Must Know About Plastic Metal Inserts

What is Plastic Wrapped Metal?

Plastic wrapped metal is a common packaging method, that is, the surface of the metal is covered with a layer of plastic material to form a protective layer to protect the metal from the external environment. Commonly used plastic wrapped metal materials are PVC, PP, PE, etc.. The role of plastic wrapped metal is not only to protect the surface of the metal, but also to reduce the oxidation and corrosion rate of the metal, to extend the service life of the metal, and to improve the safety performance of the product.

Advantages of combining plastic and metal inserts

1. Enhance product durability

As the strength of plastic products itself is low, the use of metal inserts can enhance its structural strength and durability, reduce the probability of plastic fracture and other problems during the use of the product, so as to improve the life of the product.

2. Enhance product quality

The use of metal inserts can not only enhance the strength of the product, but also improve its appearance and texture, so that the product looks more upscale.

3. Reduce material waste

Embedding metal inserts in plastic products can effectively reduce material waste, improve material utilization and reduce production costs.

Implantation of plastic and metal inserts

1. Hot melt implantation

Hot melt implantation is also called hot pressing implantation. The inserts (generally copper inserts) will be heated by soldering iron (to 200-250 degrees), and the walls of the reserved holes of the plastic parts will be softened after being heated, and then the inserts will be pressed into the inserts at an even speed.

2. Mold implantation

Is in the injection molding parts before the molding of metal inserts will be fixed in the mold thimble (PIN needle), and then the injection molding machine to close the mold, injection of glue, after the mold is opened inserts and cooled plastic parts into one.

3. Direct implantation

Directly pressed inserts do not need to be heated, through the unique form of inserts, punching machine directly pressed inserts into the plastic reserved holes, generally applicable to thermosetting thermoplastics. Directly pressed inserts are designed with chamfered edges on the outside of the inserts to prevent them from coming out.

4. Slotted implantation

Slotted implantation without heating, and is divided into two types, one is inverted prismatic, through the punch press into the preset plastic holes, inserts at the bottom of the slot due to openings, the bottom of the bunch of the mouth in the external force, the threaded aperture becomes smaller, screwed into the formation of a certain amount of bolt clamping force to prevent inserts from coming out. Secondly, threaded screw-in, insert shape with sharp self-tapping threads, by screwing the insert into the plastic hole, similar to threaded bushings.

Plastic inserts need to pay attention to matters

1. Cycle time using plastic inserts will increase the cycle of parts molding, and mold maintenance costs will be significantly higher.

2. Scrap parts for various reasons, such as poor injection molding, or inserts missing, poor location, etc., will cause the whole part scrap!

3. Mold damage if the insert size is not right, or insert design is bad, will cause damage to the mold nut.

4. Fusion line This structure is very easy to produce fusion line. It is up to the mold designer to design a good mold to reduce the degree of fusion line.

5. Residual Stress: Plastic shrinks, but metal does not. When injection molding is completed, the plastic continues to shrink. And inserts to maintain its volume, so there will be a certain amount of cracks around the inserts, this is the residual stress caused. In this case, I can use a more flexible plastic material to prevent.

Plastic Covered Metal Frequently Asked Questions

1. Surface pollution

In the normal production process of metal parts and molds are easily contaminated by dust and grease impurities; it is recommended to check the metal parts and molds before molding whether there are other impurities, for the contamination of impurities can be cleaned up through the air gun in a timely manner, while the grease needs to be cleaned and dried before the molding process, it is also important to note the need for regular replacement of the operator's gloves, the air gun casing, to avoid being contaminated in the long-term production process.

2. Bonding problems

In general, the plastic can not be directly bonded to metal parts in the package before the adhesive need to be done through the adhesive primer effect, a variety of adhesives on the market at present, the adhesive effect also varies; according to the replacement of adhesive materials different replacement of the appropriate adhesive to solve the bonding problem.

3. Demolding problem

Part of the mold release agent and adhesive chemical reaction will lead to adhesive bonding performance will be reduced. Usually do not use or use as little as possible in the metal wrapped plastic products mold release agent. You can also replace the mold release agent to solve the problem of film release, mold surface treatment to improve the mold release.

4. Structural problems

In the customized plastic wrapped metal products, out of the plastic wrapping process does not understand, there are many time-consuming and laborious processes in the design. So the plastic wrapped metal product pre-development assessment is very important, must consult with the designer, according to the process to consider the efficiency of the product in mass production.

5. Metal offset

Because the metal parts belong to the covered objects, in the plastic covering process often occurs in the position of the case of offset, this situation can be adjusted by the pressure of the machine, in the placement of the time to place the correct position to solve the problem of offset.