The *COOL PLUS* technique developed and patented by our sister company SCHMETZ is available optionally over the entire BMI range of tempering furnaces (range B5_R).
This "sub-zero" treatment process, particularly well suited to treatment of stainless steels, high-speed steels and tools, takes place between the quenching and tempering cycles and offers numerous advantages.
*COOL PLUS* reduces the rate of residual austenite while increasing the hardness and dimensional stability of treated parts, which additionally retain their exceptional brilliance.
Apart from the results obtained, the *COOL PLUS* technique enables, among other things, and thanks to an increase in the hardness at the end of quenching and "sub zero" treatment, reducing the tempering cycle time and therefore the costs, and thus gains competitiveness.
This technique is characterised by liquid nitrogen injection, which vaporises once injected within the heating zone producing mixed gaseous nitrogen just like in the case of a tempering furnace.
With regard to needs inherent to clients and to the different types of jobs that we come across, the temperatures required and observed on the surface generally vary between -40°C and -120°C.
This fully automated and controlled process (thermocouple) is perfectly reproducible.
As an example and thanks to *COOL PLUS*, a X20Cr13 steel quenched at 1035°C and brought to -100°C has a hardness of 690HV as against 640HV at the end of a tempering cycle at 150°C and without "sub-zero" treatment.