Mold surface treatment technology

Mold surface treatment -Mold surface treatment technology:

Performance of a heat treatment is important to ensure the mold process. The mold as it has a direct impact on performance. Precision mold manufacturing: organizational change is uneven, incomplete and heat treatment to form the residual stress caused by mold in the heat treatment processing, assembly and use of the process of deformation of the mold, thereby reducing the accuracy of the mold, or even scrapped.

The strength of the mold: the development of improper heat treatment, heat treatment, heat treatment equipment operating status of non-standard or non-intact, causing the handle mold strength (hardness) meet the design requirements.

Mold of his working life: heat caused by the organizational structure is irrational, excessive grain size, etc., resulting in major performance, such as mold toughness, thermal fatigue performance, wear resistance and so on down, affecting the working life of the mold.

Manufacturing cost of the mold: the mold manufacturing process as intermediate or final process, heat treatment caused by cracking, distortion-tolerance and performance of ultra-poor, in most cases will die scrap, even if the repair can continue to use, will increase the working hours to extend the delivery time, improve mold manufacturing costs.

It is the quality of heat treatment technology and the mold has a very close relationship, making the two technologies in the process of modernization and promote each other and improve together. Since the 1980s, the international mold heat treatment technology developed rapidly in the field of vacuum heat treatment technology, the mold surface hardening technology and pre-hardened mold material technology.

Mold surface treatment technology
In addition to the work requirements of the mold substrate with a sufficiently high strength and toughness of rational co-ordination, the surface properties of the mold performance and service life is essential. These surface properties means: wear resistance, corrosion resistance, friction coefficient, fatigue properties. These performance improvements rely solely on the base material to improve and enhance the very limited, and it is not economical, and by surface treatment technology, can often have a multiplier effect, which is the rapid development of surface treatment technology reasons.
Die surface treatment technology, is the surface coating, surface modification or composite processing technology to change the mold surface morphology, chemical composition, structure and stress state in order to obtain the required surface properties of systems engineering. The way from the surface, can be divided into: chemical methods, physical methods, physical and chemical and mechanical methods. Although aimed at improving the performance of the new mold surface treatment technologies are emerging, but more in the mold manufacturing applications mainly nitriding, carburizing and hardening film deposition.
Nitriding gas nitriding process has, ion nitriding, liquid nitriding, etc., each nitriding method, there are several kinds of nitriding technology, steel can be adapted to different requirements of different workpieces. Because nitriding technology can form a good surface properties, and nitriding process and die steel quenching process are well coordinated, while the low temperature nitriding, after nitriding without intense cooled, small deformation of the mold, so mold nitriding surface hardening technology is used earlier, is the most widely used.
Mold carburizing main purpose is to enhance the overall strength and toughness of the mold, that mold the work surface with high strength and wear resistance, thus the introduction of the technical idea is to use lower-grade materials, namely, by carburizing and quenching to instead of higher-level material, thereby reducing manufacturing costs.
Hardened film deposition technology is more mature is CVD, PVD. In order to increase the bonding strength of the surface film, and now the development of a variety of enhanced CVD, PVD technology. Hardening of the earliest film deposition technology tools (cutting tools, cutting tools, measuring tools, etc.) on the application, with excellent results, a variety of tools has hardened coating film as a standard process. Mold since the 1980s began to use hardened coating film technology. The current technical conditions, the hardened film deposition technology (primarily equipment) costs higher, still only in the number of sophisticated, long-life die on the application, if the heat treatment used to establish the center, then it hardened coating film will greatly reduce the cost of More die if we adopt this technology can improve our overall level of mold manufacturing.
The pre-hardened mold material technology
Mold during the manufacturing process of heat treatment is in use most of the mold of a long process, since the 1970s began, the international community to put forward the idea of ​​pre-hardened, but the machine tool and cutting tool stiffness constraints, pre-hardened hardness using the hardness of the mold can not be achieved, so the pre-hardened technology R & D investment is not. As the machine tool and cutting tool performance improvement, pre-hardened mold material technology development has accelerated, to the 1980s, the international timber industry developed in the plastic mold using the ratio of pre-hardened module has reached 30% (currently above 60%). China in the late 1990s began to use the pre-hardened module (mainly with imported products).
The pre-hardened mold material technology manufacturers primarily in the mold material development and implementation. By adjusting the chemical composition of steel and equipped with the appropriate heat treatment equipment, stable quality can be mass-produced pre-hardened module. China in the pre-hardened mold material technology, the late start, is small and can not meet the domestic requirements of mold.
The use of pre-hardened mold material, mold manufacturing process can be simplified to shorten the manufacturing cycle of the mold to improve the manufacture of precision molds. Can be expected, with the advances in processing technology, pre-hardened mold materials will be used for more mold type.

Mold vacuum heat treatment technology

Vacuum heat treatment technology is developed in recent years a new type of heat treatment technology, it has the characteristics, it is urgently needed in the mold, such as not to prevent oxidation and decarburization heating, vacuum degassing or degassing to remove hydrogen embrittlement, thereby enhancing the material (parts) of the ductility, toughness, and fatigue. Vacuum heating is slow, small parts inside and outside temperature and other factors, determines the vacuum heat treatment of parts caused by small deformation.

The cooling medium by using different vacuum oil quenching can be divided into the cold vacuum quenching, vacuum gas quenching, vacuum and vacuum quenching water nitrate austempering. Mold vacuum heat treatment in the main application is the cold vacuum oil quenching, vacuum gas quenching and vacuum annealing. To maintain the workpiece (such as mold) the fine characteristics of vacuum heating, cooling agent and cooling process of selection and development is very important, die quenching process is mainly the use of oil-cooling and air cooling.

For machining after heat treatment no longer face the mold, vacuum annealing after quenching as far as possible, especially in vacuum hardening of the workpiece (mold), it can improve the surface quality associated with the mechanical properties, such as fatigue, surface brightness, and corrosive.

Heat treatment process of computer simulation techniques (including the organization of simulation and performance prediction techniques) the successful development and application of intelligent heat treatment makes it possible to mold. As the mold of small quantities (even one piece), and variety of features, and performance requirements of high heat and does not allow for waste characteristics, but also makes intelligent mold heat treatment is a must. Intelligent mold heat treatment include: a clear mold structure, timber, heat treatment process performance requirements of the mold heating temperature field, stress field distribution in the process of computer simulation of mold cooling temperature field, phase-change process and computer simulation of stress field distribution in the heating and cooling process the development of simulation quenching heat treatment equipment, automation and control technology. Foreign industrial countries like the United States, Japan, in a vacuum high-pressure gas quenching, have been carried out in this area of technology research and development, the main target is mold.