In precision mechanics, among the machining performed on ferrous materials for the production of one of the thermal treatments of precision mechanical components, the heat treatment is used to change the molecular structure of metals.
In heat treatments, the effect of heat allows metals to enhance their characteristics depending on their use; within the different treatment cycles the heating and cooling phases can increase the hardness and the resistance of metals used in precision mechanics.
Heat treatments history
The first metals heat treatments in precision mechanics can be found 4,000 years ago when the tempering process was already used for the production of lances and knives.
Tempering is in fact the oldest heat treatment and consists in heating the metal component up to very high temperatures and then cooling it down by immersing it in a liquid, in ancient times it was water while now we use particular cooling oils.
The tempering gives the component a hardness that can be increased even a hundred times compared to the physical properties of the original metal.
The most common heat treatments
Among the most used heat treatments in precision mechanics we have:
Different stages of heat treatment
Every heat treatment follows three phases:
Heating: in this phase the mechanical part is heated evenly in order to avoid temperature differences with consequent expansion.
Permanence and temperature: once the regime temperature to which the metal is brought has been determined, heat treatment is carried out
Cooling phase: it’s fundamental as it allows to bring the piece to room temperature. The different cooling rates give the material a different structure and consequently a different response to the mechanical application.