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   Home - Steel Making - Categories - Manufacturing and the Economy of Machinery

Steel Making

Rate Of Cooling
At the option of the manufacturer, the above treatment of gea...

High Speed Steel
For centuries the secret art of making tool steel was handed ...

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

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

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

High-carbon Machinery Steel
The carbon content of this steel is above 30 points and is ha...

Quenching The Work
In some operations case-hardened work is quenched from the bo...

Leeds And Northrup Optical Pyrometer
The principles of this very popular method of measuring tempe...

Take Time For Hardening
Uneven heating and poor quenching has caused loss of many ve...

Forging High-speed Steel
Heat very slowly and carefully to from 1,800 to 2,000 deg.F....

Effect Of A Small Amount Of Copper In Medium-carbon Steel
This shows the result of tests by C. R. Hayward and A. B. Joh...

Heat Treatment Of Steel
Heat treatment consists in heating and cooling metal at defin...

Properties Of Steel
Steels are known by certain tests. Early tests were more or l...

Introduction Of Carbon
The matter to which these notes are primarily directed is the...

Detrimental Elements
Sulphur and phosphorus are two elements known to be detrimen...

Carbon-steel Forgings
Low-stressed, carbon-steel forgings include such parts as car...

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

Protectors For Thermo-couples
Thermo-couples must be protected from the danger of mechanica...

Annealing Method
Forgings which are too hard to machine are put in pots with ...

High-chromium Or Rust-proof Steel
High-chromium, or what is called stainless steel containing f...



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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