What is plastic wrapped metal?

Plastic wrapping metal is a common way of packaging, that is, covering the surface of the metal 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 and so on. The role of plastic wrapped metal is not only to protect the metal surface, but also to reduce the oxidation and corrosion speed of the metal, extend the service life of the metal, and improve the safety performance of the product.

Plastic and metal forming process

1, injection molding

2, extrusion molding

3, hollow molding

4, compression molding

The upper and lower die is installed between the upper and lower templates of the press, the plastic raw materials are directly added to the cavity, the mold is closed, the plastic is filled with the cavity under heat and pressure, and the plastic parts are obtained after curing and shaping.

5, pressure injection molding

Also known as transfer molding, it is also one of the main molding methods for thermosetting plastics. It is to load plastic pellets into the feeding chamber of the mold, and under heating and pressure, the molten plastic fills the cavity through the pouring system at the bottom of the feeding chamber of the mold, and then solidifies and forms.

6, solid phase molding

The plastic is formed at the melting temperature, there is no obvious flow state in the forming process, and it is mostly used for the secondary molding processing of plastic sheets, such as vacuum molding, compressed air molding and pressure molding, etc., the original is mostly used for thin-wall molding, and the first is used for the manufacture of thick wall parts.

7, extrusion molding

Extrusion molding is also called extrusion molding or extrusion, it is in the extruder through heating, pressure and make the material flow state through the mouth molding method.

8, extrusion molding

Extrusion molding is one of the forming methods of thermosetting fiber reinforced plastics. It is used to produce profiles with fixed section shape and unrestricted length. The molding process is to pull out the continuous fiber impregnated with resin glue through a heating die, and then further solidify the resin through a heating chamber to prepare a unidirectional high-strength continuously reinforced plastic profile.

9. Injection molding

Injection molding (injection molding) is a method by which thermoplastic or thermosetting molding is first uniformly plasticized in a heated barrel and then pushed into a closed mold cavity by a plunger or moving screw.

10, other molding

Rolling forming, casting forming, rotomizing forming, foam forming, etc.

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The role of plastic wrapping metal

1. Prevent pollution

During transportation, storage and use, metals are susceptible to various pollutants, such as water, oil, dust, etc., which can cause damage to the metal surface. By wrapping the plastic, a protective barrier can be formed to prevent contaminants from contacting the metal surface and protect the cleanliness of the metal.

2. Anti-oxidation and corrosion

Many metals are susceptible to oxidation and corrosion, for example rust is the product of iron in the presence of oxygen. By wrapping the plastic layer, it can prevent the metal surface from coming into direct contact with oxygen, moisture or other corrosive substances, reduce the oxidation and corrosion rate of the metal, and extend the service life of the metal.

3. Improve safety performance

Plastic wrapped metal can not only play a role in protecting the metal, but also improve the safety performance of the product, for example, in the food industry, after the metal container of food is wrapped in plastic, it can prevent metal contamination of food and metal and food detection

Plastic wrapped metal common problems

1. Surface contamination

In the normal production process, metal parts and molds are easy to be polluted by dust and grease impurities; It is recommended to check whether there are other impurities in the metal parts and molds before forming, and the contaminated impurities can be cleaned in time by the air gun, while the grease needs to be cleaned and dried before forming production. In addition, it should be noted that the operator's gloves and air gun casing need to be replaced regularly to avoid being polluted in the long-term production process.

2. Bonding problem

Generally speaking, the plastic can not be directly bonded to the metal, before the coating need to be through the adhesive coating effect, the current market a variety of adhesives, the bonding effect is also different; You can change the appropriate adhesive according to the different bonding materials to solve the bonding problem.

3. Demoulding problem

Some release agents will react chemically with adhesives, which will lead to a decrease in adhesive bonding performance. Usually do not use release agent or less when making metal-coated plastic products. You can also change the release agent to solve the problem of film removal, mold surface treatment to improve the release.

4. Structural problems

In the custom plastic coated metal products, due to the lack of understanding of the coating process, there are many time-consuming and laborious processes in the design. Therefore, the pre-development evaluation of plastic metal products is very important, and it is necessary to negotiate with the designer to consider the efficiency of the product in mass production according to the process.

5, metal offset

Since metal parts are covered objects, position deviation often occurs in the plastic coating process, which can be solved by adjusting the pressure of the machine and placing the correct position when placed