What are the characteristics of plastic mold steel? There are several types of plastic mold steel

In the past, there was no special plastic mold steel in China, and the general plastic mold was manufactured with normalized 45 and 40cr after quenching and tempering, so the mold hardness is low, the wear resistance is poor, the surface roughness value is high, the appearance quality of the processed plastic products is poor, and the service life of the mold is low; Precision plastic molds and high-hardness plastic molds are made of CRWMO, CR12MOV and other alloy tool steels, which not only have poor machining performance, but also are difficult to process complex cavities, and cannot solve the problem of heat treatment deformation. As a result, the steel for special plastic molds has been developed in China, and certain progress has been made. China has its own special die steel series, has been included in the national standards of two kinds, namely 3cr2mo and 3cr2mnnimo, into the industry standard has more than 20 kinds, has been promoted and applied in the production of more than 10 kinds of new plastic mold steel, the initial formation of China's plastic mold steel system.

With the more and more widely used in industry and daily life, the demand for die steel in the plastic mold industry is also increasing. In plastic molding and processing, the quality of the mold is self-evident in ensuring product quality. Plastic molds have developed in the direction of precision, large-scale and multi-cavity, and the requirements for the performance of plastic mold steel are getting higher and higher, and the performance of plastic mold steel should be determined according to the requirements of plastic type, product use, production batch, dimensional accuracy and surface quality.

1.Steel for plastic molds covers a wide range of steels, from ordinary steels to special steels. This is especially evident in the early days of plastic molds, which are now becoming more formal and advanced.

The chemical composition of the steel for the mold is basically the same as that of the alloy tool steel, but its metallurgical quality is higher, the processing is excellent, and it is beneficial to heat treatment.

2.The performance requirements of plastic mold steel are strict, and heat treatment is difficult.

3.In order to avoid the deformation or other heat treatment problems of mold parts in the process of strengthening and toughening, the market for mold steel in the form of pre-hardening has become more common.

4.Plastic products made of petrochemical products have different degrees of corrosiveness, so corrosion-resistant steel is also widely used.

5.With the application of pre-hardened steel and non-quenched and tempered steel, easy machinability is also a feature of plastic mold steel.

Molds include cold stamping dies, wire drawing dies, drawing dies, embossing dies, wire rolling dies, thread rolling dies, cold heading dies and cold extrusion dies. Steel for cold work molds, according to the working conditions of the tools it manufactures, should have high hardness, strength, wear resistance, sufficient toughness, as well as high hardenability, hardenability and other process properties. The alloy tool steel used for this type of use generally belongs to high-carbon alloy steel, the carbon mass fraction is above, chromium is an important alloying element of this type of steel, and its mass fraction is usually not more than 5%.

However, for some steel with high wear resistance requirements and small deformation after quenching, the highest chromium mass fraction can reach 13%, and in order to form a large number of carbides, the carbon mass fraction in the steel is also very high, up to the maximum. Cold work die steels have a high carbon content, and most of their microstructures belong to eutectic steels or lesteite steels. Commonly used steels include high-carbon low-alloy steel, high-carbon high-chromium steel, chromium-molybdenum steel, medium-carbon chromium-tungsten steel, etc.

Die steel is a steel grade used to make cold stamping dies, hot forging dies, die-casting dies and other molds. Molds are the main processing tools for manufacturing parts in industrial sectors such as machinery manufacturing, radio instruments, motors, and electrical appliances. The quality of the mold directly affects the quality of the pressure processing process, the accuracy output of the product and the production cost, and the quality and service life of the mold are mainly affected by the mold material and heat treatment in addition to the reasonable structural design and processing accuracy.

Die steel can be roughly divided into three categories: cold-rolled die steel, hot-rolled die steel and plastic die steel, which are used for forging, stamping, cutting, die-casting, etc. Due to the different uses of various molds and complex working conditions, the steel used for molds, according to the working conditions of the molds it manufactures, should have high hardness, strength, wear resistance, sufficient toughness, as well as high hardenability, hardenability and other process properties.

Due to the different uses and complex working conditions, the performance requirements for mold steels are also different.

The types of die steels that are divided according to their chemical composition and use.

ASSAB 618 is a high-quality pre-hardened flexible plastic mould steel, ASSAB 618 steel is an alloy steel made from vacuum degassing, which has high purity, ultrasonic inspection, uniform hardness and metallographic structure, and easy polishing.

ASSAB 618 chemical composition (%)

Csimnmocrniassab 618 Usage: Plastic mold for mirror polishing requirements, ordinary plastic injection mold. Injection molds and extrusion molds for thermoplastics, blowing molds. Forming tool, compression, brake mold (flame hardening or nitrogen treatment can be applied as needed.)

718 mold steel, China's grade 3Cr2Nimo is a P20 improved steel grade developed on the basis of P20 (3Cr2Mo), and the quality has been greatly improved, so that it can fill the lack of P20 mold steel and meet the occasions when P20 mold steel does not meet the requirements. At present, in addition to the above-mentioned Chinese standard steel grades, there are also P20+NI steel grades in China's mold steel market. Sweden's 718,718H (ASSAB), PX5 PX4 (Japan Datong Special Steel), GS-711, GS-738, GS-312, GS-318 (Germany Thyssen), Austria's M238 EcoPlus (Bailu Company), CS718 (China Great Wall Special Steel), SWP20 (Shanghai Wugang Company), etc., so in addition to not being used for plastic mold parts with corrosion resistance requirements, It is currently the typical grade of the most widely used general-purpose plastic mold steel.

Often referred to as "high-grade" plastic mold steel, newly developed new steel grades often use it as a typical comparison.

718 mold steel can be carburized to further improve surface properties.

718 mold steel is used in the same way as P20 type mold steel, but due to better hardenability and superior performance, it can make large-size, high-grade plastic mold forming parts. With the development of plastic molds, there will be more better and newer improved mold steel numbers, and my B30H of Baosteel in China is an example.

718 mold steel chemical composition (mass fraction, %)

Element C SI MN MO CR NI standard.

Content (%), YB T127-1997

With the development of the petrochemical industry, plastics have become an important industrial raw material. Plastic products have been widely used in automobiles, home appliances, chemicals, instruments, telecommunications, building materials, military and other industries, and the world has entered a new era of replacing steel with plastic. At the same time, plastic mold steel has also been significantly developed, so what characteristics does it have that other mold steels do not have, let me introduce it to you.

1.Plastic mold steel has high strength, so when manufacturing plastic molds, it can cope well with local plastic deformation, resulting in damage such as dents, wrinkles, pittings and edge and corner collapse on the surface.

2.Plastic mold steel has strong wear resistance, and the effectiveness of the mold is often caused by surface wear. , because when purchasing die steel, you should choose a die steel with strong wear resistance to ensure the service life of the mold.

3.Plastic mold steel has good machinability, because the shape of injection molded parts is often more complex, so the mold needs to have good machinability, and the plastic mold is difficult to process after hardening, and sometimes even cannot be processed. In order to improve the hardness, heat treatment is necessary.

4.Plastic mold steel should have good corrosion resistance, because the mold working environment is harsh, often because the surface of the mold is corroded, resulting in the service life of the mold is reduced. Therefore, the mold needs to be highly resistant to corrosion.

5.Compared with other mold steels, the cost of plastic mold steel is lower. Because the production cost of plastic is much lower than that of steel, the application of plastic mold steel is more extensive.

Compared with the plastic mold, the steel mold has higher hardness, stronger quality, and is not easy to damage, but the quality of the steel mold is heavier, and the operation is more difficult for the construction personnel, and a certain labor cost is required.

If a large mold is used, the angle steel skeleton is used, then its durability and service life will be very high. When making larger templates, steel molds are used to make them because the plastic molds are easy to deform.

The market demand for plastic molds is very large, because plastic molds can be produced quickly in large quantities, with fast mold speed, good machinability and corrosion resistance, can be molded at one time, and the cost is low; Therefore, in terms of efficiency, it is more appropriate to choose plastic molds. However, the durability of plastic molds is worse than that of steel molds, and steelless molds have a long lifespan.

To sum up, if you are making a mold with a small size, it is recommended to use a plastic mold for the base wheel, because the product is easy to demold, simple to make, fast molding, and more convenient to use; If you want to make a large mold, it is recommended to use a steel mold, because it is not easy to be damaged while having high hardness, and improves the service life.

All in all, both have their own characteristics and disadvantages, we need to choose according to their own type of work, hidden training consulting related experts to use correctly, reasonable selection of steel molds and plastic molds, so as to minimize the cost.

X40CrMOV51 hot work steel, 40CrMnMo7 pre-hardened plastic mold steel, C45W medium carbon steel, etc. It has high hardness, strength, wear resistance, sufficient toughness, and high hardenability and hardenability.

1. X40CRMOV51 hot work steel, uniform material and good hardenability; Excellent machinability and polishing performance; High toughness and plasticity, good all-round properties; Good high and low temperature wear resistance; Good high temperature fatigue resistance, good heat resistance; The internal organizational structure is meticulous, which is better than that of conventional furnace steel.

2. X40CRMOV51 hot work steel, good toughness and ductility, excellent machinability and polishability, can resist temperature fusion and thermal stress fatigue, is stable in size after heat treatment, not easy to deform, and has excellent red hardness. 2344 steel is suitable for general metal die-casting, extrusion die, and casting die. PA, POM, PS, PE, EP plastic molds.

Hot work die steel is suitable for aluminum, zinc, alloy die casting molds.

3. 40crmnmo7 pre-hardened plastic mold steel is an abrasive alloy steel produced in Germany, which is used for camshafts and connecting rods.

Fourth, 40crmnmo7 pre-hardened plastic mold steel is produced by "ultra-pure" process and pre-hardened, showing a high degree of microscopic purity and excellent homogeneous structure, excellent polishability and photo-etching pattern. After heat treatment, the processing and polishing performance is good, nitriding treatment can be carried out, suitable for chrome plating and other surface treatment, the material hardness is uniform (to 400mm thick), good toughness, good machining performance. The gold structure is martensite and bainite structure.

5. C45W steel is a medium carbon steel, which is cheap and easy to process, and is suitable for surface hardening treatment such as high-frequency induction heating and quenching.

Commonly used die steel materials are as follows:

1. Punching die steel.

Punching die steel is mainly used for punching forming of various sheets, and its cutting edge is subjected to strong friction and impact during the working process, this die steel has high wear resistance, impact toughness and fatigue fracture resistance.

2. Extrusion die steel.

Extrusion die steel is mainly used for deformation molding, when working, the punch is subjected to huge pressure, and the die is subjected to huge tension; Due to the violent flow of metal in the cavity, the punch and the die working surface are subjected to strong friction, and the temperature of the die surface rises by 200-300, this die steel has high deformation resistance, wear resistance and fracture resistance, in addition to high tempering stability.

3. Drawing die steel.

Drawing die steel is mainly used for drawing forming with a certain plastic sheet, the working stress is not large, but the entrance of the die bears strong friction, has high hardness and wear resistance, and the roughness of the working surface is low.

4. Bending die steel.

Bending die steel is mainly used for bending and forming metal materials with certain plasticity, and the load acting on the mold is not very large, but there is a certain friction, and it has high wear resistance and fracture ability.

5. Plastic mold steel.

Plastic mold steel is divided into thermosetting plastic compression mold and thermoplastic injection mold

Thermosetting plastic compression mold is mainly used for bending and forming with certain plastic metal materials, and the load acting on the mold is not very large, but there is a certain friction, and it has high wear resistance and fracture ability.

Thermoplastic injection mold is not too serious under heat, pressure and friction, and some plastic products contain chlorine and fluorine, which release corrosive gases when pressed, eroding the surface of the cavity, and have high corrosion resistance and certain wear resistance and toughness.

Mold steel is a steel grade used to make molds such as cold stamping dies, hot forging dies, die casting molds, etc. Mold material is the material and technical basis of the mold manufacturing industry, in which the mold steel is the traditional mold material, and its variety, specification and quality play a decisive role in the performance, service life and manufacturing cycle of the mold.

Mold Steel Properties:

Die steel is a multi-purpose comprehensive cold work tool steel. It has good adhesion resistance, high wear resistance, high toughness and good chipping resistance. After high temperature tempering, a high hardness of 55-60HRC can be obtained.

2. Therefore, for cutting the mold with complex shape by wire cutting from a large section with high hardness (>HRC59), the risk of cracking can be reduced. In addition, high-strength substrates are particularly suitable for surface treatments such as nitriding or PVD.

3. Steel is a general term for iron-carbon alloys with a mass percentage of carbon content between to. The chemical composition of steel can vary greatly, and steel that contains only carbon elements is called carbon steel (carbon steel) or ordinary steel; In actual production, steel often contains different alloying elements according to different uses, such as: manganese, nickel, vanadium and so on.

4. The application and research history of steel by human beings is quite long, but until the invention of the Bayesian steelmaking method in the 19th century, the production of steel was a high-cost and low-efficiency rolling work.

5. Nowadays, steel has become one of the most widely used materials in the world with its cheap and reliable properties, and is an indispensable component of the construction industry, manufacturing industry and people's daily life. It can be said that steel is the material basis of modern society. <