and Production phases
and drawing machines
Cold drawing produces the deformation of the material thanks to the forces impressed by equipment and matrices, defined “chains”, characterised by shaped holes of increasingly reduced diameter.
The product is subjected to different “steps” of drawing, each of which coinciding with the traction in a different matrix of progressively smaller section, until the established dimensions are reached.
The advantages ensured by the cold drawing technique are numerous:
- The material is not removed but only deformed, minimising the waste of raw material
- The surface finishes obtained are excellent
- The products obtained guarantee precise dimensions and minimum tolerances
Through the cold drawing process it is possible to modify the density, structure, mechanical and technological properties of the material according to the required design specifications.
At the end of the hardening (due to cold drawing) the material is very hard, so annealing is carried out to improve the mechanical properties.
Our annealing process, in static bell and carriage furnaces with a controlled atmosphere, generally involves a prolonged stay at a temperature close to Ac1 with possible oscillations around that temperature, in order to cause the spheroidization of the precipitated carbides.
The spheroidizing process improves the mechanical properties as it reduces the fragility of the material; moreover, as a consequence, there is a clear increase in the elongation and a lowering of the mechanical tensile strength.
A further drawing phase can be carried out on the wires coming from the annealing; in fact, the material coming from this heat treatment, appropriately cooled to room temperature, is sent to the finisher where it undergoes the skinpassing operation.
The processing to the finisher is nothing more than a drawing that imparts low elongation values (0.2-3.5%) depending on the quality and use of the material; moreover, depending on the use of the drawn, the customer asks for different surface finishes.
With regard to the influence of the skinpassage on the mechanical characteristics, the skinpassage guarantees a lowering of the yield strength of the material that normally involves an improvement of the printability characteristics.