Theory of vacuum hardening
Vacuum heat treatment
Vacuum heat-treatment is a basis of high-quality heat treatment for tooling industry (for example for car industry).
After carrying out of any process of heat treatment on a surface of a detail there is an oxidation when they was influenced by air. It leads to labour-consuming and expensive subsequent processing. Therefore, heat treatment is preferable to spend in an oxygen-free atmosphere. In addition to use high-clean protective gases, is used vacuum as the best protection against oxidation and which is the most effective atmosphere.
In the beginning of the development, vacuum technologies were applied only for special materials in the aviation industry, now vacuum technologies are widely applied for heat treatment of hot work tool steels, cold work tool steels, mould steels and high speed steels.
For carrying out of heat treatment the party of details is located in the vacuum furnace. The vacuum furnace represents the chamber working under pressure and equipped by thermal insulation and system of heating. After loading the chamber vacuumized so, that air leaves from the chamber, i.e. there is no risk of oxidation of details. Details heat up in vacuum. After corresponding endurance at the corresponding temperature of quenching, detail are cooled by nitrogen at the maximal pressure 12 bar. Increased quenching speed and uniform cooling. Flexible dynamic cooling system with alternating cooling gas flow, giving the furnace high flexibility. Can be adapted to a wide range of materials, geometries and loads.
Advantages of vacuum heat treatment:
- Considerable decrease of warping and dimensional changes;
- Getting of optimal hardness;
- Total absence of oxidation and decarburizing;
- Possibility of considerable decreasing of allowance on finishing operations (grinding, polishing);
- Good control and documentation of the processes;
- Possibility of application for wide range of materials, due to regulation of the speed of cooling;
- Assured getting of the stable results;
- Getting of the clean and bright details;
- Uniformity of properties on the section of the details;
- Quality, service life of the tool, working capacity and wear resistance raises;