The latest technology, industrial status and industrial development of die casting die


Die casting die is a tool for casting metal parts, a tool for completing the die casting process in a special die casting die forging machine. The basic process of die casting is: the liquid metal is filled into the cavity of the mold at low speed or high speed. The mold has an active cavity surface. It is forged under pressure with the cooling process of the liquid metal, which not only eliminates the shrinkage cavity and porosity defects of the blank, but also makes the internal organization of the blank reach the broken grain of the forged state. The comprehensive mechanical properties of blank are improved remarkably.

The latest technology

New surface treatment technologies of various die casting molds continue to emerge, but generally speaking, they can be divided into the following three categories:

(1) Improvement technology of traditional heat treatment process;

(2) Surface modification technology, including surface thermal diffusion treatment, surface phase transformation strengthening, electric discharge strengthening technology, etc.;

(3) coating technology, including electroless plating.

Die casting die is a major category of die. With the rapid development of automobile and motorcycle industry in China, the die casting industry has ushered in a new period of development, and higher requirements are required for comprehensive mechanical property and life of die casting mold. Luo Baihui, Secretary-General of the International Mold Association, believes that it is still difficult to meet the constantly improving performance needs only by relying on the application of new mold materials. It is necessary to apply various surface treatment technologies to the surface treatment of die casting mold to achieve the requirements of high efficiency, high accuracy and high life of die casting mold.

Among all kinds of molds, the working conditions of die casting molds are more demanding. Pressure casting is to make molten metal in high pressure, high speed full mold cavity and die casting molding, repeated contact with hot metal in the process of work, so the die casting mold is required to have high heat fatigue, thermal conductivity, wear resistance, corrosion resistance, impact toughness, red hardness, good demolstering, etc. Therefore, the surface treatment technology of die casting die has high requirements.

  1. Improvement technology of traditional heat treatment process

The traditional heat treatment process of die casting mold is quenching-tempering, and then the surface treatment technology has been developed. Because of the variety of materials that can be used as die casting molds, the same surface treatment technology and process applied on different materials will produce different effects. Shi Kefu proposed the pretreatment technology for the substrate and surface treatment technology of the mold.

On the basis of the traditional process, the suitable processing technology for different mold materials was put forward, so as to improve the performance of the mold and improve the life of the mold. Another development direction of heat treatment technology improvement is to combine traditional heat treatment technology with advanced surface treatment technology to improve the service life of die casting die.

Such as the chemical heat treatment method of carbonitriding, combined with conventional quenching and tempering process of NQN (namely the carbonitriding, quenching and carbonitriding composite reinforcement, not only get high surface hardness, and the effective depth of hardening layer increase, rational distribution of carbonitriding layer hardness gradient, tempering stability and corrosion resistance, so as to make the die casting mould in good heart department performance at the same time, Surface quality and performance are greatly improved.

2, surface modification technology

Surface thermal diffusing technology
This type includes carburizing, nitriding, boronizing and carburizing, sulfur carburizing and so on.
Carburizing and carburizing
The carburizing process can be used in cold, hot and surface strengthening of plastic die, which can improve the life of die. For example, the die casting die of 3Cr2W8V steel is carburized first, then quenched at 1140 ~ 1150℃ and tempered twice at 550℃. The surface hardness can reach HRC56 ~ 61, so that the die life of the die casting nonferrous metals and their alloys can be increased by 1.8 ~ 3.0 times.

Carburizing treatment, the main process methods are solid powder carburizing, gas carburizing, and vacuum carburizing, ion carburizing and carburizing atmosphere in the formation of carbon nitriding. Among them, vacuum carburizing and ion carburizing is the technology developed in the past 20 years, the technology has the characteristics of fast infiltration, uniform layer, carbon concentration gradient and small deformation of the workpiece, will play a more and more important role in the die surface, especially the precision die surface treatment.

Nitriding and related low temperature thermal diffusing technology

This type includes nitriding, ion nitriding, carbon nitriding, oxygen nitriding, sulfur nitriding and sulfur carbon nitriding, oxygen nitriding and sulfur ternary infiltration methods. These methods have simple processing technology, strong adaptability, low infiltration temperature, generally 480 ~ 600℃, small deformation of the workpiece, especially suitable for the surface strengthening of the precision mold, and the nitride layer has high hardness, good wear resistance, and good adhesion resistance.

3Cr2W8V steel die casting mold, after quenching and tempering, 520 ~ 540℃ nitriding, the service life of the mold is 2 ~ 3 times higher than that of the non-nitriding mold. Many die casting molds made of H13 steel in the United States need nitriding treatment and nitriding instead of a tempering. The surface hardness is as high as HRC65 ~ 70, and the core hardness of the mold is low and the toughness is good, so as to obtain excellent comprehensive mechanical properties. Nitriding process is a commonly used process for surface treatment of die casting mold. However, when thin and brittle white bright layer appears in the nitriding layer, it cannot resist the effect of alternating thermal stress, which is easy to produce micro cracks and reduce thermal fatigue resistance.

Therefore, in the nitriding process, the process should be strictly controlled to avoid the formation of brittle layer. The secondary and multiple nitriding processes are proposed in foreign countries. By USING THE METHOD OF repeated nitRIDING, THE white bright layer of nitride which is easy to produce microcracks in service process can be decomposed, the thickness of nitriding layer can be increased, and at the same time, there is a very thick residual stress layer on the surface of the die, so that the life of the die can be improved obviously. In addition, salt bath carburization and salt bath sulfur carburization are also used.

These processes are widely used in foreign countries, but rarely seen in China. For example, TFI+ABI process is impregnated in alkaline oxidizing salt bath after nitrocarburizing in salt bath. The surface of the workpiece is oxidized and black, and its wear resistance, corrosion resistance and heat resistance have been improved. The life of die casting die of aluminum alloy treated by this method is increased by hundreds of hours. Again, such as the oxynit process developed in France after the nitriding treatment of sulfur and nitrogen carburization, applied to non-ferrous metal die casting mold is more characteristic.

Industry status quo

Present situation of domestic die casting mould

China’s die-casting die industry develops rapidly, and the total production of die-casting die increases significantly. The domestic total production of die-casting die is second only to the United States, and has become a real country of die-casting die. To have such achievements mainly comes from China’s advantaged market and relatively cheap resources and labor advantages, it is already very obvious price performance has a great advantage in the international casting trade market, according to the situation, the future development prospects of Chinese casting industry is very broad.

Although China’s die casting mold has made significant breakthroughs during the “Eleventh Five-Year Plan” period. But its international reputation ranking is still low, the output is also rising but most die casting mold only for domestic demand. Due to technical constraints, the quality is difficult to break through. At the same time, some large domestic demand enterprises also frequently extend olive branches to foreign die casting enterprises. The serious trade deficit makes it difficult for domestic die casting enterprises

International die casting mold status

In the context of the increasingly fierce competition in the international die casting die market, the Japanese die casting die industry is also trying to reduce production costs. In terms of market size, the decline in both output and domestic demand has been most pronounced in Japan. Japanese DIE MANUFACTURERS PAY more attention TO polishing and grinding process in technology, while German die manufacturers start by improving the precision and efficiency of machining and discharge machining, so as to reduce the time of manual machining. Japanese die casting mold industry is gradually turning the mold with low technology content to the production of low labor cost areas, and only the production of products with high technology content in the country. The trend of Japan’s accelerated transfer to foreign countries makes the use of Japanese die casting mold reduce.

Analysis of the factors influencing the development of Chinese die casting industry

The main reasons restricting the development of die casting mould industry in our country are as following: First, there are still many shortcomings in the use of raw materials as die casting mould in our country. Secondly, the development of Chinese die casting mould industry has been greatly hindered by the backward technology. Thirdly, the supporting system of Chinese die casting industry is not perfect.

The industrial development

The products of the new alloy die casting mould are sold well in our country, but this phenomenon does not represent very good sales in the world. The requirements of foreign markets often have different with domestic. According to relevant experts, there are three main reasons restricting the export sales of die casting in China. First, there are still many shortcomings in the use of raw materials for die casting in domestic; Secondly, the backward technology is also one of the obstacles to the development of Chinese casting mould industry. Thirdly, the supporting system of Chinese die casting industry is not perfect. These are the bottlenecks that restrict the development of Chinese die-casting mould industry. Only by breaking through these bottlenecks can our die-casting mould industry increase its share in the international market.

Die casting and mould have distinction to have connection again already, the birth of the die-casting mould industry is both the most perfect combination, in other words, die casting, mold, die-casting mold is three different industries, its relations mainly exist in several ways: integration of die casting, mold, mould manufacturing, and rarely give other companies do mould; Professional die casting mold manufacturing, no die casting; Only die casting, no mold manufacturing capacity. With the intensification of industrial division of labor, the gradual blurring of industrial boundaries and the development of industrial cross-cutting, the three industries should strengthen contact, learn from each other, and integrate the three industries into one. In the form of “integration”, it is believed that our country’s die casting mold industry at the later period will usher in more and greater development opportunities and spac