Vacuum Heat Treatment Technology for Dies and Moulds

Successful development and application of computer simulation technology for heat treatment process (including structure simulation and performance prediction technology) make it possible to intellectualize heat treatment of dies. Because of the characteristics of small batch (or even single piece) and multi-variety in mould production, as well as the high requirement of heat treatment performance and the characteristics of no waste products, it is necessary to intellectualize the processing of mould.

Intelligent heat treatment of dies includes:

Define the structure, material and heat treatment performance requirements of the die.

Computer simulation of temperature field and stress field distribution in die heating process;

Computer simulation of temperature field, phase transformation process and stress field distribution in die cooling process;

The simulation of heating and cooling process;

The formulation of quenching process;

Automatic control technology of heat treatment equipment;

In the field of vacuum high pressure gas quenching, developed countries, such as the United States and Japan, have carried out research and development in this field, aiming mainly at dies and moulds.

According to the different cooling medium used, vacuum quenching can be divided into vacuum oil quenching, vacuum air quenching, vacuum water quenching and vacuum nitrate isothermal quenching. Vacuum oil quenching, vacuum gas quenching and vacuum tempering are the main applications of vacuum heat treatment of dies. In order to maintain the excellent characteristics of vacuum heating of workpieces (such as dies), the selection and formulation of coolant and cooling technology are very important. Oil-cooled and air-cooled are mainly used in the quenching process of dies.

Vacuum heat treatment technology is a new type of heat treatment technology developed in recent years. Its characteristics are urgently needed in die manufacturing, such as preventing oxidation and decarbonization, vacuum degassing or degassing, eliminating hydrogen embrittlement, thereby improving the plasticity, toughness and fatigue strength of materials (parts). The factors such as slow vacuum heating and small temperature difference between inside and outside of parts determine the small deformation of parts caused by vacuum heat treatment process.

For the die working face which is no longer machined after heat treatment, vacuum tempering is adopted as far as possible after quenching, especially for the vacuum quenched workpiece (die), which can improve the mechanical properties related to surface quality. Such as fatigue performance, surface brightness, corrosion and so on.