Requirements for material selection of precision plastic moulds

- Dec 31, 2017 -

Requirements for material selection of precision plastic moulds

(1) meeting the requirements of working conditions

1. wear resistance

When plastic deformation occurs in the cavity of precision plastic mold, the billet moves and slides along the surface of the cavity, resulting in severe friction between the surface of the cavity and the billet, resulting in the failure of the precise plastic mold due to wear. Therefore, the wear resistance of the material is one of the most basic and most important properties of the precision plastic mold.

Hardness is the main factor affecting the wear resistance. In general, the higher the hardness of the precision plastic mold parts, the smaller the wear and the better the wear resistance. In addition, the wear resistance is also related to the type, quantity, shape, size and distribution of carbides in the material.

2. strong toughness

Most of the precision plastic mold working conditions are very bad, some often bear large impact load, resulting in brittle fracture. In order to prevent the sudden brittle fracture of the precision plastic mold parts during work, the precision plastic mold should have high strength and toughness.

The toughness of the precision plastic mold mainly depends on the carbon content, grain size and microstructure of the material.

3. fatigue fracture properties

In the working process of precision plastic mould, the fatigue fracture is often caused by the long-term action of cyclic stress. Its form has small energy multiple impact fatigue fracture, tensile fatigue fracture contact fatigue fracture and bending fatigue fracture.

The fatigue fracture performance of the precision plastic mold mainly depends on its strength, toughness, hardness, and the content of inclusions in the material.

4. high temperature performance

When the working temperature of the precision plastic mold is higher, the hardness and strength will decrease, which causes the early wear or plastic deformation of the precision plastic mould. Therefore, the precision plastic mould material should have high anti tempering stability to ensure that the precise plastic mold has higher hardness and strength at working temperature.

5. resistance to cold and hot fatigue

Some precision plastic mould in the repeated heating and cooling in the working process, so that the cavity surface tension and pressure stress effect caused by cracking and spalling, increase the friction surface, hinder plastic deformation, resulting in reduced size precision, precision plastic mould failure. Cold and hot fatigue is one of the main forms of the failure of the precision plastic moulds, which should have a high resistance to cold and heat fatigue for this kind of precision plastic mold.

6. corrosion resistance

Some precision plastic molds, such as plastic mold, are exposed to strong corrosive gases such as HCI and HF after being heated, which cause erosion of the surface of precision plastic mold cavity, increase the surface roughness and intensify wear failure.

(two) meet the requirements of process performance

In general, the manufacture of precision plastic moulds should be made by forging, cutting, heat treatment and so on. In order to ensure the manufacturing quality and reduce the production cost of precision plastic moulds, the materials should have good Forgability, machinability, hardenability, hardenability and grindability. It should also have small oxidation, decarburization sensitivity and quenching deformation and cracking tendency.

1. Forgability

It has low deformation resistance, good plasticity, wide forging temperature range, low forging and cold cracking and low precipitation of reticulate carbide.

2. annealing process

The spheroidizing annealing temperature range is wide, the annealing hardness is low, the fluctuation range is small, and the spheroidization rate is high.

3. machinability

The cutting consumption is large, the cutting tool loss is low, and the machining surface roughness is low.

4. oxidation and decarburization sensitivity

When heated to high temperature oxidation with good decarburization rate is slow, not sensitive to the heating medium, produce pitting tendency.

5. hardenability

After quenching, it has uniform and high surface hardness.

6. hardenability

After quenching, the hardened hardened layer can be obtained, and the quenched medium can be quenched.

7. tendencies of quenching and dehiscence

The volume change of conventional quenching is small, the shape is warped, the distortion is slight, and the abnormal deformation tendency is low. The cracking sensitivity of the conventional quenching is low, and it is not sensitive to the quenching temperature and the shape of the workpiece.

8. grindability

The wheel is relatively small loss, no limit of grinding burn of large amount, is not sensitive to the quality of the grinding wheel and the cooling conditions, not prone to abrasion and grinding crack.

(three) meet the economic requirements

In the selection of precision plastic mold, it is necessary to consider the principle of economy and reduce the cost of manufacturing as much as possible. Therefore, under the premise of satisfying the use performance, the first choice is the lower price, the carbon steel can be used without alloy steel, and the imported materials can be used with the domestic material.

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WT Hardware And Plastics Limited

Our company founded in 2011,Shenzhen WT Hardware And Plastics Limited takes pride in meeting and exceeding in customer requirements, WT is located in Shenzhen , where is the manufacturing center is in.

We WT are professional in moulds and molding parts, we also support struture design and offer assistance in material selection . You are welcome to look towards WT Mold as an extension of your R&D department , an arm of your design group and manufacture partner.

We have been striving to excellent quality at competitive price, “Quality and Service First”, the principle that we oursure , is exactly why we have established business relationships with customers from all over the world , More than 80% of our molds are exported to USA, EU, CLS, South America, and other Asian countries.

WT Hardware And Plastics Limited

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Tel: 86-755-27673590

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Main Product: Plastic Injection Mold & Plastic Parts, Die Casting, CNC Machining