Vacuum Carburizing-One Step Ahead
By Janusz Kowalewski, SECO/WARWICK Corp., USA, jkowalew@secowarwick.com
This article describes the vacuum carburizing
process, benefits and results .
The
SECO/WARWICK Vacuum Carburizing process has been developed to
operate in cell manufacturing operations found in commercial
heat treating shops or JIT manufacturing plants.
The standard line of furnaces consists of both one and
two zone models. The
double zone model has one chamber for heating and the other for
high pressure gas quench up to 20 bar (N2 or N2/He2).
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Step One - SECO/WARWICK's Vacuum
Carburizing Furnace |
The
front heating chamber utilizes convection heating, and when this
chamber is backfilled up to 2 bar with nitrogen, the fan
circulated gas will reduce the heating cycle time by 20% to 40%.
This timesaving occurs from ambient to 1400 degrees F, which is
the most efficient temperature range for convection heating.
After 1400 degrees F the furnace curved graphite heating elements
heat more efficiently by radiation.
The
SECO/WARWICK Vacuum carburizing furnace is very easy to operate. The carburizing cycle is carried out automatically, according
to a pre-programmed recipe with carburizing gas dosing being
carried via programmable mass flow control valves with also
supportive hydrogen dosing and programmable pressure
oscillation.
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Step 2 - The Process Cycle |
The
carburizing process is performed in the 1 – 20 TORR partial
pressure and in the temperature range of 1790 degrees F to
1920 degrees F. The furnace is equipped with a built-in
control system with a software program that controls all typical
carburizing processes by the preloaded recipes.
The second cold zone is a separate high-pressure inner gas cooling
chamber for gas quenching.
The load can be quenched for straight hardening, or
quenching from equalizing temperature after carburizing. The
single zone models runs the heating and cooling in the same
chamber. Parts
after carburizing and quenching are as clean and bright as they
would be after a typical vacuum heat treatment.
There is no need for washing after heat treatment.
The process advantage includes:
- Elimination of
the inner oxidation
- Lack of
cementite
- Full automation
of the process
- Very low
consumption of carburizing factor (ethylene or acetylene)
- Lower
distortion
- Clean and
environmental friendly process.
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Step 3 - Finished Parts |
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