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Steel Making

A Satisfactory Luting Mixture
A mixture of fireclay and sand will be found very satisfactor...

The Quenching Tank
The quenching tank is an important feature of apparatus in c...

Temperature Recording And Regulation
Each furnace is equipped with pyrometers, but the reading an...

The Thermo-couple
With the application of the thermo-couple, the measurement of...

SULPHUR is another element (symbol S) which is always found i...

Protective Screens For Furnaces
Workmen needlessly exposed to the flames, heat and glare from...

Preventing Decarbonization Of Tool Steel
It is especially important to prevent decarbonization in such...

Making Steel Balls
Steel balls are made from rods or coils according to size, st...

Carbon Tool Steel
Heat to a bright red, about 1,500 to 1,550 deg.F. Do not ham...

Carburizing Material
The simplest carburizing substance is charcoal. It is also th...

Annealing Alloy Steel
The term alloy steel, from the steel maker's point of view, r...

Tempering Round Dies
A number of circular dies of carbon tool steel for use in too...

Heating Of Manganese Steel
Another form of heat-treating furnace is that which is used ...

Heat Treatment Of Milling Cutters Drills Reamers Etc
THE FIRE.--Gas and electric furnaces designed for high heats ...

Instructions For Working High-speed Steel
Owing to the wide variations in the composition of high-speed...

PHOSPHORUS is an element (symbol P) which enters the metal fr...

Heat-treating Department
The heat-treating department occupies an L-shaped building. ...

A Chromium-cobalt Steel
The Latrobe Steel Company make a high-speed steel without tun...

Tempering Colors On Carbon Steels
Opinions differ as to the temperature which is indicated by t...

Affinity Of Nickel Steel For Carbon
The carbon- and nickel-steel gears are carburized separately...

Hardening Operation


Hardening a gear is accomplished as follows:
The gear is taken from the furnace by the furnaceman and placed in
the lower die, surrounding the centering jaws, as shown at H in
Fig. 62 and C in Fig. 63. Air is then turned into the cylinder
D, and the piston rod E, the die carrier B, the top die F
and the expander G descend. The pilot H enters a hole in the
center of the lower die, and the expander G enters the centering
jaws I, causing them to expand and center the gear C in the
lower die. On further advance of the piston rod E, the expander
G is forced upward against the pressure of the springs J and
the upper die F comes in contact with the upper surface of the
gear. Further downward movement of the dies, which now clamp the
work securely, overcomes the resistance of the pressure weight
K (which normally keeps up the plunger A), and the gear is
submerged in the oil. The quenching oil is circulated through a
cooling system outside the building and enters the tempering machine
through the inlet pipe L. When the machine is in the position
shown, the oil passes out through the ports M in the lower plunger
to the outer reservoir N, passing to the cooling system by way of
the overflow O. When the lower plunger A is forced downward,
the ports M are automatically closed and the cool quenching oil
from the inlet pipe L, having no other means of escape, passes
through the holes in the lower die and the grooves in the upper,
circulating in contact with the surfaces of the gear and passes to
the overflow. When the air pressure is released, the counterweights
return the parts to the positions shown in Fig. 63, and the operator
removes the gear.

The gear comes out uniformly hard all over and of the same degree of
hardness as when tempered in an open tank. The output of the machine
depends on the amount of metal to be cooled, but will average from
8 to 16 per hour. Each machine is served by one man, two furnaces
being required to heat the work. A slight excess of oil is used
in the firing of the furnaces to give a reducing atmosphere and
to avoid scale.

Next: Carburizing Low-carbon Sleeves

Previous: Temperature Recording And Regulation

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