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Steel Making

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

Hardening Operation
Hardening a gear is accomplished as follows: The gear is tak...

Bessemer Process
The bessemer process consists of charging molten pig iron int...

Preventing Carburizing By Copper-plating
Copper-plating has been found effective and must have a thick...

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

Annealing In Bone
Steel and cast iron may both be annealed in granulated bone. ...

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

Alloying Elements
Commercial steels of even the simplest types are therefore p...

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

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

Gas Consumption For Carburizing
Although the advantages offered by the gas-fired furnace for ...

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

Knowing What Takes Place
How are we to know if we have given a piece of steel the ver...

The Packing Department
In Fig. 56 is shown the packing pots where the work is packe...

The forgings can be hardened by cooling in still air or quen...

Piston Pin
The piston pin on an aviation engine must possess maximum res...

Refining The Grain
This is remedied by reheating the piece to a temperature slig...

Manganese adds considerably to the tensile strength of steel,...

The Care Of Carburizing Compounds
Of all the opportunities for practicing economy in the heat-t...

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

Leeds And Northrup Optical Pyrometer


The principles of this very popular method of measuring temperature
are sketched in Fig. 123.

The instrument is light and portable, and can be sighted as easily
as an opera glass. The telescope, which is held in the hand, weighs
only 25 oz.; and the case containing the battery, rheostat and
milliammeter, which is slung from the shoulder, only 10 lb.

A large surface to sight at is not required. So long as the image
formed by the objective is broader than the lamp filament, the
temperature can be measured accurately.


Distance does not matter, as the brightness of the image formed
by the lens is practically constant, regardless of the distance
of the instrument from the hot object.

The manipulation is simple and rapid, consisting merely in the turning
of a knurled knob. The setting is made with great precision, due to
the rapid change in light intensity with change in temperature and
to the sensitiveness of the eye to differences of light intensity.
In the region of temperatures used for hardening steel, for example,
different observers using the instrument will agree within 3 deg.C.

Only brightness, not color, of light is matched, as light of only
one color reaches the eye. Color blindness, therefore, is no hindrance
to the use of this method. The use of the instrument is shown in
Fig. 127.

Next: Optical System And Electrical Circuit Of The Leeds & Northrup Optical Pyrometer

Previous: Placing The Thermo-couples

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