Used hardening furnaces etc. for processing metal
Heat treatment of steel or cast iron workpieces is generally conducted in order to extract particular properties that are required for the application or for subsequent processing. Therefore, heat treatments can be subdivided into various metalworking processes. Generally, these are processes that bring about a structural transformation in the material or processes that treat the surface of a work piece.
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In order to achieve these things, there are various thermal and thermo-chemical processes that can be used. Annealing (particularly soft annealing) is used to increase the machinability of the materials. Stress-relief annealing also falls under this category. These thermal processes are used to reduce the stress in a workpiece, which has built up from previous processes e.g. from rollers. Two types of thermal processes are annealing and hardening. Hardening can either take place over the whole piece of the material or only on the surface, where it can reduce the risk of the tool steel breaking. This means, that a hard core is surrounded by a hard crust.
The thermo-chemical processes can be subdivided into carbonising, nitriding, borating and carbonisation. There is a variety of possibilities for tempering, like soft annealing, normal annealing, stress-relief annealing, homogenisation, coarse-grain annealing and recrystallisation annealing. These methods are based on production specific requirements. A thermal heat treatment like surface hardening, general hardening, annealing, and austempering is attributed to the application. Thermo-chemical processes (e.g. nitration, ferritic nitrocarburisation, carbonitriding and carbonisation) are used to, for example, increase the carbon content on specific areas of the workpiece.
The characteristics of treating iron with heat have been known for millennia. Modern technologies and the use of effective furnaces, annealing ovens, and annealing furnaces allow for the workpiece to be processed and reach its desired material characteristics. Programmable temperature and time control ease the work process.
High-quality tool steel is processed during the construction of tools. To allow for this production, the stress is relieved and then processed. These basically formed workpieces are (depending on their future use) hardened either completely or only on the surface. Afterwards, the workpiece will be further processed with a grinding machine. Therefore, it is important to ensure that the manufacturing process does not result a soft annealed surface again. This can be prevented through cooling or careful delivery. Hard metal is produced through sintering. This should not be processed using a cooling device, even if they do not continually cool down. Otherwise, hair line cracks could occur in the metal, as hard metals cannot tolerate rapid changes in temperature. A carefully undertaken heat treatment can enormously increase the technological characteristics of a material. For example, the cutting punch for punching machinery contains a tough core and a hardened surface that is several tenths of a millimetre thick.
Several companies have specialised in the manufacturing of machines used for heat treatment. Some of the most recommended suppliers include MLW, NABERTHERM, ELIOG.