1–10 of about 625 matches for molding materials processes
PRECISION IN THE FOUNDRY (3210)
Transactions of the American Foundrymen's Society V 69 P 409-421, 1961 (13 p)
Steel castings offer a definite advantage to the designer
of aerospace vehicles in the form of high strength
and attendant weight and volume savings. The author's
company's designers have utilized these advantages in
the design of a supersonic trainer. Steel castings used
on the trainer have been a problem from the standpoint
of mechanical properties, and the causes of these
problems appear to originate in the foundry. Controls
in the foundry are required and will be more important
as the alloys become more complex and the casting requirements
more stringent. Foundrymen need to reevaluate
their position and up-grade their product in
order to get their fair share of business from the aerospace
CASTING FINISH AS AFFECTED BY SAND ADDITIVES (2532)
Transactions of the American Foundrymen's Society V 63 P 306-312, 1955 (7 p)
Casting finish is becoming in
creasingly important. New processes
such as shell molding, D process,
and investment casting have been
developed with one of their features
being good finish.
Over the years, various means
have been used to improve the surface finish of green sand castings.
Today a variety of additives is being
used in molding sands in an attempt
to minimize cleaning costs, eliminate or reduce machining operations, or improve appearance. The
trend in sand seems to be toward
finer sands with a specified number
Several years ago, a series of test
castings was made using sands from
the various molding units in the
plant. Some production sands produced expansion defects on the test
casting though they could produce
a satisfactory finish on the size and
weight of jobs on the molding units
in which they were used. A test pattern 12 in. square and varying from
5/8 to 2 in. thick was used. The pat
tern was made of plywood and the
thickness was increased by adding
more pieces of wood. Castings were
made to compare the molding sand
mixes, pouring times, and iron temperatures.
FORMATION OF SLAGS IN CAST IRON AND EFFECT ON CASTING (3333)
Transactions of the American Foundrymen's Society V 70 P 612-621, 1962 (10 p)
Reactions between materials in close contact with metals
and alloys occur easier when the latter are in the liquid.
rather than in the crystalline slate. The possibilities for
such reactions to take place are many, e.g., reactions between
metal on the one hand and ceramics, molding
materials or the atmosphere on the other hand.
This paper deals with the reactions between liquid
metals and oxygen. Investigations of reactions between
liquid nonferrous metals and atmospheric oxygen, have
alreadv been carried out on frequent occasions. Reactions
between oxygen and metals, such as lead and zinc, have
been studied with respect to the products formed and
also the times taken for these reactions. It has been found
that the latter are functions of the temperature and the
composition of the allow and when plotted give either a
linear or a parabolic graph.
In contrast, reactions between liquid cast iron and
oxygen of the air. have hardly been investigated. This may
have stemmed from the belief that the slags encountered
in castings were, in many cases, products of the reaction
between melt and ceramic materials (in the widest sense).
In the course of this investigation it was found that
the observations published in the literature agreed with
the authors' findings. These confirm that the slags appearing
in spongy areas of castings arc developed bv the interaction
of liquid iron and the air: this occurring in the
ladle, in Ihe pouring stream or even in the mold.
This preliminary contribution to the clarification of
the problem of the kinetics of slag formation confirms
the fact, known from the literature, that such reactions
depend on the composition of the cast iron and especially
on the silicon, managanese and sulfur contents. The
author shows thai a close relationship exists between the composition of a cast iron, the temperature at which the
oxide films are formed and the composition of the slags
and their properties. In melts of cast iron that are rich
in sulfur a sulfide slag is the first to develop, followed by
a silicate slag. The temperature interval between the beginning
of oxide film formation and the complete covering
of the bath surface with slag is considerably smaller for
melts low in manganese than for melts high in manganese.
The possible cause of this may be a difference in wettability
of metal and slag respectively.
Summarizing, it is concluded that the formation of
spongy areas in an iron casting is determined by the
silicon, managanese and sulfur contents of the cast iron,
by the pouting temperature and by the time during which
the molten metal is exposed to the air.
RESINS AND SANDS FOR SHELL MOLDING (2347)
Transactions of the American Foundrymen's Society V 61 P 367-377, 1953 (11 p)
The proper choice of a sand and the resin binder for shell
molding determine to a large extent whether the process will be
successful and economic. Most resins perform differently in degree and their utility depends upon their physical properties
and the mechanism of the thermosetting reaction. Some are far
superior to others. A cheap sand with the desired fineness is not
always an economic shell molding sand. The performance of a
sand on the automatic machine is dependent greatly upon the
particle size distribution and grain shape, but of extreme importance is the condition of the surface of the sand.
The choice of molding materials may be guided by proper
screening methods and once production has started, control
methods must be inaugurated to insure smooth and economic
STUDY OF HIGH TEMPERATURE PROPERTIES OF SHELL MOLDS (2951)
Transactions of the American Foundrymen's Society V 66 P 484-494, 1958 (11 p)
A large percentage of the shell-mold casting scrap
is due to shell cracking and shell expansion defects.
This report covers work performed in cooperation with
the AFS Shell Molding Materials Testing Committee
(8-N) in order to determine the causes of such casting
defects when various sand and resin mixes were used.
Hot expansion and tensile strength tests of the shell
mixes were performed in the laboratory in an attempt
to correlate these tests with the expansion defects
found in test pattern castings.
MOLDING SANDS, MOLDING METHODS AND CASTING DIMENSIONS (2749)
Transactions of the American Foundrymen's Society V 64 P 398-405, 1956 (8 p)
New molding processes have received a great deal
of attention in the past few years. Shell molding,
D-process, pressure molding, C02 -process, and diaphragm molding, to name a few, have been widely
heralded as providing a new era of progress in mold
ing. Amid the claims and accomplishments of the
new methods, it is worthwhile to take a new and
critical look at an old process, green sand molding.
What are the true capabilities of the process? How
well is it now being used relative to its ultimate possibilities? What can be done to get the best results from
it? Complete answers to these questions cannot be
given for lack of certain fundamental information.
However, the general direction of improvements can
To get the best green-sand casting, the best mold
possible must be produced from a combination of
molding sand and molding equipment. This mold
should have uniform sand density, high hardness, high
strength and thermal stability. Inevitably certain
characteristics of the sand mixture will affect the
ability of the process to obtain such a mold. There
fore, consider first the molding sand.
STATUS OF THE TECHNOLOGY FOR CASTING TITANIUM (2862)
Transactions of the American Foundrymen's Society V 65 P 499-512, 1957 (14 p)
The first serious interest in titanium was started
in about 1946. Metallurgists reasoned that the high
melting point of titanium, 3140 F, might make it applicable for service at elevated temperatures. In addition, the low density of titanium, approximately
40 per cent that of stainless steel, added to the
interest in this metal.
The potentiality that titanium might possess a
high strength-to-weight ratio for use at elevated temperatures made it appear particularly attractive for
military aircraft, especially the jet planes designed
for supersonic speeds.
OPTIMUM CARBON DIOXIDE MOLDING - CRITICAL FORMULATIONS OF SODIUM SILICATE AND SAND (3040)
Transactions of the American Foundrymen's Society V 67 P 553-576, 1959 (24 p)
The difficulty of poor collapsibility, predominate
as a limitation in the sodium silicate-C02 method of
sand bonding, is obviated by establishing simple laboratory test methods to determine an optimum quantity
of sodium silicate binder. This is designated as the
minimum critical percentage for each sand considered.
Additives such as sugar, coarse grain silica flour and
iron oxide, properly used, contribute to the flowability,
ramming qualities and green strength and enhance collapsibility as well as provide hot strength and cushion
ing during thermal changes.
The binder requirements should be developed on the
hypothesis of adhesive bonding rather than on the
basis of a mortar composition, which fills voids between
the grains. Adhesive binders are most effective in thin
films and with the greatest number of sand grain to
grain adhesive contacts uniformly distributed in the
sand structure. The viscosity and penetrating qualities
of the binder composition determine the degree of correlation that binder requirements have to B.E.T.
specific area measurements.
The B.E.T. data can be used to designate those sands
which will need more or less binder than their AFS
fineness number indicates. A straight line correlation
between minimum critical percentage and a dimension
al parameter calculated from AFS fineness data, shape
factors, ratio multipliers and specific volume ratios
raised to the fourth power is given.
The limitations due to high relative humidity and the
use of clay additives are discussed. Experimental data,
as well as numerous references, are used to support
COST SAVINGS WITH FLEXIBLE COREBOXES AND PATTERNS (19750821)
AFS Transactions 1975 p. 437-440 Available as Preprint No. 75-33 @ $3.00
A presentation of the flexible mold process, a new concept in coreboxes and patterns utilizing elastomeric materials is given. The patented process combines nobake technology with flexible one-piece coreboxes and patterns, eliminating costly core assemblies and loose pieces, while producing higher quality castings with lower casting and pattern costs. The flexible mold, when properly applied, also provides further savings to the casting customer in reduction of machining and the removal of normal foundry restrictions in casting design and engineering.
THE FOUNDRY INDUSTRY--AN URGENT NEED TO CAST A NEW IMAGE (19690994)
AFS Canadian Regional Conference, Oct. 1969, Canadian Metalworking/Machine Production--June, 1969, p. 11-18
This extensive paper, to use a modern cliche, tells it like it is by investigating numerous phases of the metal casting industry. For example, it shows how metal casting is feeling the pinch of competitive materials and processes. It points out how metal casters have left themselves vulnerable to competitive processes by not paying the attention to product quality and reliability required to meet the demands of today's markets. It further points out in detail that although the technology to upgrade standard areas of foundry operation has become available in recent years, it is still begging for application. It shows examples of how many jobbing metal casters could use some of the techniques used in the captive operations. It points out examples of how a general overhaul of processes is needed along with a program to educate industrial designers to the advantages and limitations inherent in castings could do much to promote their use. It further discusses a variety of new processes suitable for use in the large and small company. These processes discussed range from melting through molding, coremaking, pouring, shakeout and cleaning. Production control as to metals and sand are discussed in detail and it is pointed out that the size of the company does not have to be a limiting factor in its use.
1–10 of about 625 matches for molding materials processes
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