Informational Site NetworkInformational Site Network
   Home - Steel Making - Categories - Manufacturing and the Economy of Machinery

Steel Making

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

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

Although it is possible to work steels cold, to an extent de...

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

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

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

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

Hardening High-speed Steel
In forging use coke for fuel in the forge. Heat steel slowly ...

Carburizing By Gas
The process of carburizing by gas, briefly mentioned on page ...

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

Cyanide Bath For Tool Steels
All high-carbon tool steels are heated in a cyanide bath. Wi...

For Milling Cutters And Formed Tools
FORGING.--Forge as before.--ANNEALING.--Place the steel in a ...

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

Double Annealing
Water annealing consists in heating the piece, allowing it to...

Properties Of Alloy Steels
The following table shows the percentages of carbon, manganes...

It is considered good practice to quench alloy steels from th...

The Effect Of Tempering On Water-quenched Gages
The following information has been supplied by Automatic and ...

Critical Points
One of the most important means of investigating the properti...

Flange Shields For Furnaces
Such portable flame shields as the one illustrated in Fig. 1...

An Automatic Temperature Control Pyrometer
Automatic temperature control instruments are similar to the ...

Rate Of Cooling


At the option of the manufacturer, the above treatment of gear
forgings could be substituted by normalizing the forgings at a
temperature of from 1,550 to 1,600 deg.F. The most important criterion
for proper normalizing, consisted in allowing the forgings to cool
through the critical temperature of the steel, at a rate not to exceed
50 deg.F. per hour. For the two standard steels used, this consisted in
cooling from the normalizing temperature down to a temperature
of 1,100 deg.F., at the rate indicated. Forgings normalized in this
manner will show a Brinell hardness of from 177 to 217. The question
has been repeatedly asked as to which treatment will produce the
higher quality finished part. In answer to this I will state that
on simple forgings of comparatively small section, the normalizing
treatment will produce a finished part which is of equal quality to
that of the quenched and annealed forgings. However, in the case of
complex forgings, or those of large section, more uniform physical
properties of the finished part will be obtained by quenching and
annealing the forgings in the place of normalizing.

The heat treatment of the finished gears consisted of quenching
in oil from a temperature of from 1,420 to 1,440 deg.F. for the No.
X-3,340 steel, or from a temperature of from 1,500 to 1,540 deg.F.
for No. 6,140 steel, followed by tempering in saltpeter or in an
electric furnace at a temperature of from 650 to 700 deg.F.

The question has been asked by many engineers, why is the comparatively
low scleroscope hardness specified for gears? The reason for this is
that at best the life of an aviation engine is short, as compared with
that of an automobile, truck or tractor, and that shock resistance
is of vital importance. A sclerescope hardness of from 55 to 65
will give sufficient resistance to wear to prevent replacements
during the life of an aviation engine, while at the same time this
hardness produces approximately 50 per cent greater shock-resisting
properties to the gear. In the case of the automobile, truck or
tractor, resistance to wear is the main criterion and for that
reason the higher hardness is specified.

Great care should be taken in the design of an aviation engine
gear to eliminate sharp corners at the bottom of teeth as well
as in keyways. Any change of section in any stressed part of an
aviation engine must have a radius of at least 1/32 in. to give
proper shock and fatigue resistance. This fact has been demonstrated
many times during the Liberty engine program.

Next: Connecting Rods

Previous: Gears

Add to Add to Reddit Add to Digg Add to Add to Google Add to Twitter Add to Stumble Upon
Add to Informational Site Network

Viewed 3469