Three principles that need to be met for mold material selection

Mold material selection is a very important part of the entire mold making process. The selection of mold materials needs to meet three principles: (1) the mold meets the work requirements such as wear resistance and toughness; (2) the mold meets the process requirements; (3) at the same time, the mold should meet the requirements of economic applicability.

1. The mold meets the requirements of working conditions

1. Wear resistance

When the blank is plastically deformed in the mold cavity, it both flows and slides along the surface of the cavity, causing severe friction between the surface of the cavity and the blank, resulting in the failure of the mold due to wear. Therefore, the wear resistance of the material is one of the most basic and important properties of the mold.

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

2. Strong toughness

Most of the working conditions of the mold are very bad, and some often bear a large impact load, which leads to brittle fracture. In order to prevent sudden brittle fracture of mold parts during operation, the mold must have high strength and toughness. The toughness of the mold mainly depends on the carbon content, grain size and organizational state of the material.

3. Fatigue fracture performance

During the working process of the mold, fatigue fracture is often caused under the long-term action of cyclic stress. Its forms are: small energy multiple impact fatigue fracture, tensile fatigue fracture, contact fatigue fracture and bending fatigue fracture.

The fatigue fracture performance of the 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 mold is high, the hardness and strength will decrease, resulting in early wear of the mold, or plastic deformation and failure. Therefore, the mold material should have high tempering resistance stability to ensure that the mold is under the working temperature. , with high hardness and strength.

5. Thermal fatigue resistance

Some molds are in a state of repeated heating and cooling during the working process, which causes the surface of the cavity to be subjected to tension, pressure and stress, causing surface cracking and peeling, increasing friction, hindering plastic deformation, and reducing dimensional accuracy. lead to mold failure.

Hot and cold fatigue is one of the main forms of failure of hot work dies, and such dies should have high resistance to cold and heat fatigue.

6. Corrosion resistance

When some molds such as plastic molds are working, due to the presence of chlorine, fluorine and other elements in the plastic, after being heated, a strong corrosive gas is decomposed, which erodes the surface of the mold cavity, increases its surface roughness, and aggravates wear failure.

2. The mold meets the process performance requirements

The manufacture of molds generally has to go through several processes such as forging, cutting, and heat treatment.

In order to ensure the manufacturing quality of the mold and reduce the production cost, the material should have good forgeability, machinability, hardenability, hardenability and grindability; it should also have small oxidation, decarburization sensitivity and quenching properties. Deformation and cracking tendency.

1. Forgeability

It has low hot forging deformation resistance, good plasticity, wide forging temperature range, low tendency for forging cracking and cold cracking and precipitation of network carbides.

2. Annealing manufacturability

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

3. Machinability

The cutting amount is large, the tool loss is low, and the machined surface roughness is low.

4. Oxidation and decarburization sensitivity

When heated at high temperature, it has good anti-oxidation performance, slow decarburization speed, insensitive to heating medium, and small tendency to pitting.

5. Hardenability

It has a uniform and high surface hardness after quenching.

6. Hardenability

After quenching, a deep hardened layer can be obtained, which can be hardened by using a mild quenching medium.

7. Quenching deformation cracking tendency

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

8. Grindability

The grinding wheel has small relative loss, no burns, large limit grinding amount, insensitive to the quality of the grinding wheel and cooling conditions, and is not prone to wear and grinding cracks.

3. The mold meets the economic requirements

When selecting materials for the mold, the principle of economy must be considered to reduce the manufacturing cost as much as possible. Therefore, under the premise of satisfying the performance, first choose the lower price, if you can use carbon steel, you don't need alloy steel, and if you can use domestic materials, you don't need imported materials. In addition, when selecting materials, the production and supply conditions of the market should also be considered.

As a China plastic crate mould manufacturers and chair moulds factory,Taizhou Huangyan Mengsheng Plastic Mould Co.,Ltd (“MS” for short) is located in Xinqian Industrial Zone, Huangyan District, Taizhou City, a modern emerging city known as “Capital of Commerce & Trade” on the east coast of Zhejiang Province, with booming business and convenient traffic. MS is 7km away from Taizhou Train Station, 22km away from Taizhou Airport, and 160km away from Ningbo Port, the traffic passage to Asia, Africa, Europe and America.

Founded in 1994, MS own more than 40 sets of advanced imported equipment including CAD and CAM machining centers, CNC machining center, high speed CNC, double-head EDM and high-speed carving machines, as well as a self-provided 300-7,000g imported injection molding machine for mold testing and production.