030070010 Celal Selçuk Tiftik 10th week

Semi-dry Pressing

Semi-dry Pressing In semi-dry pressing, the proportion of water in the starting clay is
typically 10% to 15%. This results in low plasticity, precluding the use of plastic forming
methods that require very plastic clay. Semi-dry pressing uses high pressure to overcome
the material’s low plasticity and force it to flow into a die cavity.
Flash is often formed from excess clay being squeezed between the die sections.

(Mikell P. Groover Fundamentals of Modern Manufacturing Materials, Processes, and Systems, Fourth Edition    2010 p .374)

*There is no old definition
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Slush casting

Slush casting generally involves the procesing of low-temperature-melting alloys.
     The principle involves pouring the molten metal into a permanent mold.After the skin has frozen, the mold is turned upsidedown or slung to remove the metal still liquid.
     A thin-walled casting results, the thickness depending on the chilling effct from the mould and the time of operation.
    -The process is suitable for small production runs and is generally used for making ornamental and decorative objects and toys from low-melting point metals,such as zinc,tin and lead alloys.

A Textbook of Manufacturing Technology: (manufacturing Processes R. K. Rajput 

p.100)

*There is no old definition


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Atomic Hydrogen Arc welding

 In this method an alternating current arc is maintained between two tungsten electrodes,and at the same time, a stream of hydrogen gas is passed thru the arc and around the electrodes.
the atomic is referring to the change from an molecular state to an atomic state releasing a considerable amount of energy. I believe this was along the lines of a plasma type arc welding system that is no longer used since the advent of TIG.
As it had a monster of an hand piece but was considered extremely mobile at the time. Because of the fact that the arc is independent of the work so the work doesn't have to be grounded.
It has a complete chapter on eye protection and what happens and why you need it.
It is a good asset for the gas welding info, on sheet, SS, copper and other materials as gas welding was the most used system at the time after forge/fire welding due to costs of the equipment.

(The Science and Practice of Welding  Arthur Cyril Davies p.479)

*There is no old definition




Air arc gouging (AAG)





            The gouging process is the removal of metal at the underside of butt welds. Gouging
techniques are also used for the removal of defective material or welds.The various
forms of gouging are flame gouging, air-arc gouging, oxygen-arc gouging and metalarc
gouging.

              Air-arc gouging uses the same equipment as manual metal arc welding. The
process differs in that the electrode is made of a bonded mixture of carbon and
graphite encased in a layer of copper, and jets of compressed air are emitted from
the specially designed electrode holder. These air jets blow away the parent metal
from beneath the arc.


(The Steel Construction Institute Steel Designers Manual  2005 p.961)

*There is no old definition

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Resistance Brazing

Resistance brazing is most applicable to relatively

simple joints in metals that have high

electrical conductivity. For resistance brazing,

the workpiece, with filler metal preplaced, is

part of an electric circuit. Brazing heat comes

from either placing carbon electrodes in contact

with the brazement to conduct heat into the

work or by relying on resistance of the brazement

to generate heat.

Electrode resistance brazing is best suited to

joining of high-conductivity materials, such as

copper-base alloys. Applied to steels, which are

poor conductors, electrodes can cause local

overheating. Using this process, often only one

part of an assembly is heated by the electrode,

the other by conduction. This procedure is most

effective when brazing dissimilar materials.

During direct resistance heating of the work,

current flows for such a short time and heatingis so localized that the temperature of the workpieces does not change except in the local joint area.
Advantages of resistance brazing are that it
localizes heat and is flameless, non-contaminating,
fast, and easily controlled. Disadvantages
are that at least one workpiece, preferably all,
must conduct electricity; large work, anything
weighing over 2.3 kg (5 lb) or cross sections
larger than 33 cm2 (5 in.2) may require so much
current as to make the process too slow to be
practical; and the process does not easily heat
joints of nonuniform cross section.
In the usual application of resistance brazing,
the heating current, which is normally alternating
current, is passed through the joint itself.
Equipment is the same as that used for resistance
welding, and the pressure needed for
establishing electrical contact across the joint is
ordinarily applied through the electrodes. The
electrode pressure also is the usual means for
providing the tight fit needed for capillary behavior
in the joint. The component parts are generally
held between copper or carbon-graphite
electrodes. The heat for resistance brazing can
be generated mainly in the workpieces themselves,
in the electrodes, or in both, depending on
the electrical resistivity and dimensions.
The flux used must be conductive. Normally,
fluxes are insulators when cool and dry, but they
may become conductive from the heat of brazing.
The process is generally used for low-volume
production in joining electrical contacts
and related electrical elements.
Resistance brazing requires a transformer,
electrodes, and fixtures. Standard resistancewelding
transformers suffice for brazing, with
the required capacity depending on joint size,
heating capacity of the base material, and
desired brazing time. In high-volume production
applications, spot-welding equipment may
suffice to resistance braze, using a transformer,
upper and lower electrodes, and process controls.
For manual brazing, operators wield handheld
tongs that clamp the workpiece and hold
the electrodes. Transformer power is typically
rated at 10 to 25 kVA.Electrodes are of standard resistance-welding-
grade copper alloys or of carbon. Most
common are Resistance Welding Manufacturers
Association (RWMA) class 2, chromium
copper, and class 14, refractory (molybdenum)
metal electrodes.
With higher electrical resistivity, they generate
more heat than do RWMA electrodes andperform well for brazing highly conductive
materials. Electrodes of high electrical conductivity
braze low-conductivity materials, such as
steels.
Filler metals used for resistance brazing need
to melt at relatively low temperatures to avoid
oxidation. Most common are BAg-1, 1A, 2, 7, 8,
and 18 and BCuP-1, 2, and 5. Preplace a strip or
shim on large flat joints, a ring on cylindrical
joints, paste or powder on irregular surfaces, and
a rod for feeding additional filler to supplement
preplaced filler in large joint gaps (Table 3.6).
In resistance brazing, more so than in other
brazing processes, attention is given to selecting
from the metallurgically compatible filler metals
the one having the lowest brazing temperature,
because in resistance brazing, it is necessary
to keep the maximum local temperature
reached by the work as low as possible while
providing uniform heating of the abutting joint
surfaces and the filler metal. Fluidity of the filler
metal is not critical in most resistance brazing,
because the filler metal is usually preplaced, and
the bond area is relatively large.


(Mel M. Schwartz ,Brazing    2003, p.42)


*There is no old definition