What is induction hardening?
Induction hardening is a process where steel is
hardened by means of induction heating
and subsequent quenching in water.
Basic of Principles
Induction hardening works by placing the
part to be hardened inside an "applicator" coil
of one or more turns, through which
alternating current is passed. The coil, which
in the case of gears and sprockets is round,
is usually made of copper tubing which has
water passing through it to prevent the coil
from overheating. The piece to be hardened is
rotated within the applicator coil. At JP
Engineering multiple pieces are hardened at
the same time by placing the sprockets or
gears onto a rod and then rotating the rod,
heating the parts and then feeding the rod
downward into the quench water.
The Depth of Penetration
For T = 20°C
FFoorr TT == 880000°° CC
Power supply Frequency
0,5 - 10 1,5 15
100 - 500 0,2 1,5
Change Of Materials
d t t = 0,2
Where d = The Depth of
t = time
Major uses of induction heat
• Melting ferrous and non - ferrous metals with
temperatures up to 1800 0c.
• Heating for forging up to 1250 0c.
• Stress relieving and normalizing steels after cold
forming between 750 0c and 950 0c.
• Surface hardening of steel or cast iron workpieces
at 850 0c to 950 0c.
• Soft soldering and brazing up to 1100 0c.
• Tube and Pipe Welding.
Advantage of Induction Hardening
• Localised hardening of tooth surfaces where
hardness is needed
• Hardened teeth are pre-work hardened.
• Speed of hardening
• Depth of hardness is easily controlled
• Selected parts of the workpiece can be
• Heating time and temperature can be
• There is no smoke or soot pollution;
• Heating operation can be integrated
in semi - automatic production
• Induction equipment can usually be
operated by unskilled personal
• Very fast partial hardening;
• High production rates;
• Significant reduction in pollution,
distortion, forging scale, energy and
• High degree of reproduction and