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Placing The Thermo-couples
The following illustrations from the Taylor Instrument Compan...

Standard Analysis
The selection of a standard analysis by the manufacturer is t...

Preventing Cracks In Hardening
The blacksmith in the small shop, where equipment is usually ...

Non-shrinking Oil-hardening Steels
Certain steels have a very low rate of expansion and contract...

Tensile Properties
Strength of a metal is usually expressed in the number of pou...

Cutting-off Steel From Bar
To cut a piece from an annealed bar, cut off with a hack saw,...

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

Crankshaft
The crankshaft was the most highly stressed part of the entir...

Heat-treating Equipment And Methods For Mass Production
The heat-treating department of the Brown-Lipe-Chapin Company...

Rate Of Absorption
According to Guillet, the absorption of carbon is favored by ...

Carburizing Low-carbon Sleeves
Low-carbon sleeves are carburized and pushed on malleable-ir...

Hardness Testing
The word hardness is used to express various properties of me...

Annealing Work
With the exception of several of the higher types of alloy s...

Heat Treatment Of Lathe Planer And Similar Tools
FIRE.--For these tools a good fire is one made of hard foundr...

Effect Of Different Carburizing Material
[Illustrations: FIGS. 33 to 37.] Each of these different p...

Case-hardening Treatments For Various Steels
Plain water, salt water and linseed oil are the three most co...

The Effect
The heating at 1,600 deg.F. gives the first heat treatment w...

The Influence Of Size
The size of the piece influences the physical properties obta...

Temperature For Annealing
Theoretically, annealing should be accomplished at a tempera...

Annealing
There is no mystery or secret about the proper annealing of d...



For Milling Cutters And Formed Tools






Category: HIGH-SPEED STEEL

FORGING.--Forge as before.--ANNEALING.--Place the steel in a pipe,
box or muffle. Arrange the steel so as to allow at least 1 in.
of packing, consisting of dry powder ashes, powdered charcoal,
mica, etc., between the pieces and the walls of the box or pipe.
If using a pipe close the ends. Heat slowly and uniformly to a
cherry red, 1,375 to 1,450 deg.F. according to size. Hold the steel at
this temperature until the heat has thoroughly saturated through
the metal, then allow the muffle box and tools to cool very slowly
in a dying furnace or remove the muffle with its charge and bury
in hot ashes or lime. The slower the cooling the softer the steel.

The heating requires from 2 to 10 hr. depending upon the size of
the piece.

HARDENING AND TEMPERING.--It is preferable to use two furnaces
when hardening milling cutters and special shape tools. One furnace
should be maintained at a uniform temperature from 1,375 to 1,450 deg.F.
while the other should be maintained at about 2,250 deg.F. Keep the
tool to be hardened in the low temperature furnace until the tool
has attained the full heat of this furnace. A short time should be
allowed so as to be assured that the center of the tool is as hot
as the outside. Then quickly remove the tool from this preheating
furnace to the full heat furnace. Keep the tool in this furnace only
as long as is necessary for the tool to attain the full temperature
of this furnace. Then quickly remove and quench in oil or in a
dry air blast. Remove before the tool is entirely cold and draw
the temper in an oil bath by raising the temperature of the oil
to from 500 to 750 deg.F. and allow this tool to remain, at this
temperature, in the bath for at least 30 min., insuring uniformity
of temper; then cool in the bath, atmosphere or oil.

If higher drawing temperatures are desired than those possible
with oil, a salt bath can be used. A very excellent bath is made
by mixing two parts by weight of crude potassium nitrate and three
parts crude sodium nitrate. These will melt at about 450 deg.F. and
can be used up to 1,000 deg.F. Before heating the steel in the salt
bath, slowly preheat, preferably in oil. Reheating the hardened
high-speed steel to 1,000 deg.F. will materially increase the life
of lathe tools, but milling and form cutters, taps, dies, etc.,
should not be reheated higher than 500 to 650 deg.F., unless extreme
hardness is required, when 1,100 to 1,000 deg.F., will give the hardest
edge.





Next: Instructions For Working High-speed Steel

Previous: Lathe And Planer Tools



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