CA1300789C - Mold material for forming sandmold without requiring mold wash - Google Patents
Mold material for forming sandmold without requiring mold washInfo
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- CA1300789C CA1300789C CA 535453 CA535453A CA1300789C CA 1300789 C CA1300789 C CA 1300789C CA 535453 CA535453 CA 535453 CA 535453 A CA535453 A CA 535453A CA 1300789 C CA1300789 C CA 1300789C
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Abstract
ABSTRACT OF THE DISCLOSURE
A mold material for forming sandmolds for manufacturing metal castings, consisting essentially of an organic binder: 0.4 - 3.0 percent, a catalyst for curing the organic binder: 0.2 - 2.0 percent of, a ceramic binder: 0.05 - 2.0 percent in terms of SiO2, a catalyst for curing the ceramic binder: 0.05 - 2.0 percent, and foundry sand: the balance. The mold material can be formed into a sandmold which is excellent in both strength after exposure under a room temperature atmosphere and strength after pouring molten metal thereinto and requires no mold wash or a very small amount of mold wash as obtained by spraying or the like. The mold material may preferably further includes, if required, anti-infiltration fire-proof powder: 0.1 - 3.0 percent, a high-temperature reinforcing material: 0.1 - 3.0 percent, a viscosity adjuster: 0.1 - 2.0 percent, and/or a grannular carbon stabilizer: 0.03 - 0.5 percent.
A mold material for forming sandmolds for manufacturing metal castings, consisting essentially of an organic binder: 0.4 - 3.0 percent, a catalyst for curing the organic binder: 0.2 - 2.0 percent of, a ceramic binder: 0.05 - 2.0 percent in terms of SiO2, a catalyst for curing the ceramic binder: 0.05 - 2.0 percent, and foundry sand: the balance. The mold material can be formed into a sandmold which is excellent in both strength after exposure under a room temperature atmosphere and strength after pouring molten metal thereinto and requires no mold wash or a very small amount of mold wash as obtained by spraying or the like. The mold material may preferably further includes, if required, anti-infiltration fire-proof powder: 0.1 - 3.0 percent, a high-temperature reinforcing material: 0.1 - 3.0 percent, a viscosity adjuster: 0.1 - 2.0 percent, and/or a grannular carbon stabilizer: 0.03 - 0.5 percent.
Description
78~
TITLE OF THE INVENTION
MOLD MATERIAL FOR FORMING SANDMOLD
WITHOUT REQUIRING MOLD WASH
BACKGROUND OF THE INVENTION
This invention relates to a mold material for use in the manufacture of sandmolds for manufacturing metal castings, and more particularly to a mold material of this kind which can be formed into a sandmold which is excellent in strength after exposure under a room temperature atmosphere as well as strength after pouring molten metal into the sandmold and requires no mold wash or a very small amount of mold wash as obtained by spraying or the like.
Sandmolds used or manufacturing metal castings ~hereinafter merely called "sandmolds") are generally manuEactured by ~wo major methods, i.e. one using an organic binder or setting foundry sand having a coarse grain size of 325 mesh or less, such as silica sand, zircon sand and chromite sand (hereinafter merely called "sand"), and the other using an inorga~ic binder for setting the sand.
The method using organic binder includes a method in which phenol resin or furane resin is mixed as a binder into sand and is cured by a high-acidity curing agent such as sulfuric acid, phosphoric acid, p-toluenesulfonic acid, and xylenesulfonic acid to cause the sand to ~ set, a method in which phenol resin, polyisocyanate, and a basic catalyst are mixed into the sand, whereby the basic catalyst reacts with the phenol resin and the polyisocyanate to form 13~0~
TITLE OF THE INVENTION
MOLD MATERIAL FOR FORMING SANDMOLD
WITHOUT REQUIRING MOLD WASH
BACKGROUND OF THE INVENTION
This invention relates to a mold material for use in the manufacture of sandmolds for manufacturing metal castings, and more particularly to a mold material of this kind which can be formed into a sandmold which is excellent in strength after exposure under a room temperature atmosphere as well as strength after pouring molten metal into the sandmold and requires no mold wash or a very small amount of mold wash as obtained by spraying or the like.
Sandmolds used or manufacturing metal castings ~hereinafter merely called "sandmolds") are generally manuEactured by ~wo major methods, i.e. one using an organic binder or setting foundry sand having a coarse grain size of 325 mesh or less, such as silica sand, zircon sand and chromite sand (hereinafter merely called "sand"), and the other using an inorga~ic binder for setting the sand.
The method using organic binder includes a method in which phenol resin or furane resin is mixed as a binder into sand and is cured by a high-acidity curing agent such as sulfuric acid, phosphoric acid, p-toluenesulfonic acid, and xylenesulfonic acid to cause the sand to ~ set, a method in which phenol resin, polyisocyanate, and a basic catalyst are mixed into the sand, whereby the basic catalyst reacts with the phenol resin and the polyisocyanate to form 13~0~
-2- 70668-1~
urethane whereby the sand is set by the urethanic chemical re-action, and a method in which oil-denatured alkyd resin, metallic salt naphthenate, and polyisocyanate are mixed into sand so that they react with each other to form urethane whereby the sand is set by the urethanic chemical reaction. On the other hand, the method using inorganic binder for setting the sand includes a method in which cement is mixed into the sand to set same into a sandmold (OJ Process), and a method in which C02 gas is blown into the sand impregnated with sodium silicate to set the sand.
However, a sandmold manufactured by any of the above-mentioned conventional methods using organic binder generally does not exhibit satisfactory strength of the sandmold after pouring molten metal thereinto (hereinafter called "casting strength").
Further, when molten metal is poured into the sandmold, the organ-ic binder burns to cause unbinding oE sand particles, o~ten resulting in that part of the molten metal infiltrates into inner walls of the sandmold. 'rO prevent this infiltration of molten metal, inner walls o~ the sandmold to be in contact with molten metal have to be subjected to mold washing, i.e. coating, by painting or spraying, with a mold wash material mainly composed of carbon graphite, mica powder, charcoal powder, or talcum powder.
On the other hand, a sandmold ohtained by any of the above-mentioned methods using inorganic binder is free of molten metal infiltration as mentioned above, but the sandmold is generally inferior in strength after being exposed under a room temperature atmosphere for some time period (hereinafter called "shelf strength") and often suffers from seizure, i.e. metal is stuck to . ~ .. ~.
~3(~
urethane whereby the sand is set by the urethanic chemical re-action, and a method in which oil-denatured alkyd resin, metallic salt naphthenate, and polyisocyanate are mixed into sand so that they react with each other to form urethane whereby the sand is set by the urethanic chemical reaction. On the other hand, the method using inorganic binder for setting the sand includes a method in which cement is mixed into the sand to set same into a sandmold (OJ Process), and a method in which C02 gas is blown into the sand impregnated with sodium silicate to set the sand.
However, a sandmold manufactured by any of the above-mentioned conventional methods using organic binder generally does not exhibit satisfactory strength of the sandmold after pouring molten metal thereinto (hereinafter called "casting strength").
Further, when molten metal is poured into the sandmold, the organ-ic binder burns to cause unbinding oE sand particles, o~ten resulting in that part of the molten metal infiltrates into inner walls of the sandmold. 'rO prevent this infiltration of molten metal, inner walls o~ the sandmold to be in contact with molten metal have to be subjected to mold washing, i.e. coating, by painting or spraying, with a mold wash material mainly composed of carbon graphite, mica powder, charcoal powder, or talcum powder.
On the other hand, a sandmold ohtained by any of the above-mentioned methods using inorganic binder is free of molten metal infiltration as mentioned above, but the sandmold is generally inferior in strength after being exposed under a room temperature atmosphere for some time period (hereinafter called "shelf strength") and often suffers from seizure, i.e. metal is stuck to . ~ .. ~.
~3(~
inner walls of the sandmold. To prevent such seizure, it is necessary to add charcoal powder, coke powder, etc. into the sand, and then subject the inner walls of the resulting sandmold to mold washing. Th~ls, both of the two maJor methods require mold washing, of which the operation generally incurs about 30 - 50 percent of the total cost for manufacturing a sandmold, constituting a major factor for an increase in the manufacturing cost of sandmolds.
SUMMARY OF T~E IN~ENTION
It is therefore the object of the invention to provide a mold materlal for metal castings, which can be formed into a sandmold which is excellent in shelf strength and casting strength, and does not require mold washing at all or requires same only to a small extent.
To achieve the ob~ect, the present invention provides a mold material for formlng sandmolds, consistln~ essentially of:
(a) an orcJanic binder formed of a synthetic resin, 0.4 - 3.0 percent;
(b) a catalyst for curing the synthetic xesin, 0.2 - 2.0 percent;
(c) a ceramic binder formed of at least one material selected from the group consisting of silicate esters, hydrolyzed silicate esters, alcohol-dispersed silica sol, and water-dispersed silica sol: 0.05 - 2.0 percent in terms of SiO2;
(d) a catalyst for curing the ceramic binder:
0.05 - 2.0 pexcent; and foundry sand: the balance.
A mold material according to the invention may ~3~V~
~ 4 - 70668-14 further include, if required, at least one of the following materials:
anti-infiltration fire-proof powder, preferably having a grain size from 10 to 30 microns: 0.1 - 3.0 percent;
a high-temperature reinforcing material: 0.1 - 3.0 percent;
a ~iscosity adjuster: 0.1 - 2.0 percent; and a granular carbon stabilizer: 0.03 - 0.5 percent.
The present invention also provides a method of forming a sandmold for manufacturing metal castings, which comprises:
~i] mixing the mold material ingredients, [ii] charging the resulting mixture into a 1ask and setting the mixture at room temperature, and ~iii] removing the set molding from the ~lask.
q'he present invention ~urther provides a method for manufacturin~ a metal castincJ, which comprises:
pouring molten cast iron into the sandmold formed by the above method, and quenching the cast iron, thus forming the casting.
DETAILED DESCRIPTION
We have made man~ studies in order to obtain a mold material which can be formed into a sandmold which has excellent shelf strength and casting strength, and does not require mold wash at all or does require a very small amount of mold wash.
~7 ~3~
- 4a - 70668-14 As a result, we have reached the following findings:
(1) If a sandmold, which has been set up by the use of a binder, has high shelf strength, i.e. high strength after being exposed to the atmosphere over a certain period of time, it cannot easily crumble during casting, -thus improving the productivity as well as facilitating handling of the sandmold. Therefore, there has been a demand for a sandmold having high shelf strength. To meet such demand, if a ceramic binder formed of at least one material selected from the group consisting of silicate es-ters such as ethyl silicate, hydrolyzed silicate es-ters, silica sol of alcohol dispersed type, and silica sol of water dispersed type, and a catalyst such as isocyanate for curing the binder are added to the sand to be moLded into a sandmold, together with a conven-tional organic binder such as urane resin, the `~
~n~
resulting sandmold has shelf strength l.5 to 3 times as high as that of a sandmold set up by an organic binder alone.
(2) It ls generally accepted that a sandmold set up by organic binder alone has its casting strength dropped to one third time as high as the shelf strength thereof during casting. However, a ceramic binder as specified by the present invention, and, if required, a high-temperature reinforcing material which melts at high temperature, such as common salt, borax, and boric acid are added to the sand, then silica supplied rom the ceramic binder and the high-temperature reinforcing material such as borax are melted when heated to a high temperature, to become stuck to the sand to firmly combine sand particles together. ~s a result, the casting strength of the ~esulting sandmold drops only to about half as high as the shelE strength thereo, and further the shelf strength per se is increased, which means that the casting stxeng~h is much higher than ~hat of a conventional sandmold set up by organic binder alone.
~ 3) In the manufacture of a conventional sandmold set up by inorganic binder alone, charcoal powder, coke powder, or the like is added to the sand and the resulting sandmold is then subjected to mold washing in order to prevent molten metal from being stuck to the sand, i.e. seizure, during casting. However, if an organic binder is added together with a ceramic binder as specified by the invention, such seizure can never take place, that is, the resulting sandmold has excellent anti-seizure property.
SUMMARY OF T~E IN~ENTION
It is therefore the object of the invention to provide a mold materlal for metal castings, which can be formed into a sandmold which is excellent in shelf strength and casting strength, and does not require mold washing at all or requires same only to a small extent.
To achieve the ob~ect, the present invention provides a mold material for formlng sandmolds, consistln~ essentially of:
(a) an orcJanic binder formed of a synthetic resin, 0.4 - 3.0 percent;
(b) a catalyst for curing the synthetic xesin, 0.2 - 2.0 percent;
(c) a ceramic binder formed of at least one material selected from the group consisting of silicate esters, hydrolyzed silicate esters, alcohol-dispersed silica sol, and water-dispersed silica sol: 0.05 - 2.0 percent in terms of SiO2;
(d) a catalyst for curing the ceramic binder:
0.05 - 2.0 pexcent; and foundry sand: the balance.
A mold material according to the invention may ~3~V~
~ 4 - 70668-14 further include, if required, at least one of the following materials:
anti-infiltration fire-proof powder, preferably having a grain size from 10 to 30 microns: 0.1 - 3.0 percent;
a high-temperature reinforcing material: 0.1 - 3.0 percent;
a ~iscosity adjuster: 0.1 - 2.0 percent; and a granular carbon stabilizer: 0.03 - 0.5 percent.
The present invention also provides a method of forming a sandmold for manufacturing metal castings, which comprises:
~i] mixing the mold material ingredients, [ii] charging the resulting mixture into a 1ask and setting the mixture at room temperature, and ~iii] removing the set molding from the ~lask.
q'he present invention ~urther provides a method for manufacturin~ a metal castincJ, which comprises:
pouring molten cast iron into the sandmold formed by the above method, and quenching the cast iron, thus forming the casting.
DETAILED DESCRIPTION
We have made man~ studies in order to obtain a mold material which can be formed into a sandmold which has excellent shelf strength and casting strength, and does not require mold wash at all or does require a very small amount of mold wash.
~7 ~3~
- 4a - 70668-14 As a result, we have reached the following findings:
(1) If a sandmold, which has been set up by the use of a binder, has high shelf strength, i.e. high strength after being exposed to the atmosphere over a certain period of time, it cannot easily crumble during casting, -thus improving the productivity as well as facilitating handling of the sandmold. Therefore, there has been a demand for a sandmold having high shelf strength. To meet such demand, if a ceramic binder formed of at least one material selected from the group consisting of silicate es-ters such as ethyl silicate, hydrolyzed silicate es-ters, silica sol of alcohol dispersed type, and silica sol of water dispersed type, and a catalyst such as isocyanate for curing the binder are added to the sand to be moLded into a sandmold, together with a conven-tional organic binder such as urane resin, the `~
~n~
resulting sandmold has shelf strength l.5 to 3 times as high as that of a sandmold set up by an organic binder alone.
(2) It ls generally accepted that a sandmold set up by organic binder alone has its casting strength dropped to one third time as high as the shelf strength thereof during casting. However, a ceramic binder as specified by the present invention, and, if required, a high-temperature reinforcing material which melts at high temperature, such as common salt, borax, and boric acid are added to the sand, then silica supplied rom the ceramic binder and the high-temperature reinforcing material such as borax are melted when heated to a high temperature, to become stuck to the sand to firmly combine sand particles together. ~s a result, the casting strength of the ~esulting sandmold drops only to about half as high as the shelE strength thereo, and further the shelf strength per se is increased, which means that the casting stxeng~h is much higher than ~hat of a conventional sandmold set up by organic binder alone.
~ 3) In the manufacture of a conventional sandmold set up by inorganic binder alone, charcoal powder, coke powder, or the like is added to the sand and the resulting sandmold is then subjected to mold washing in order to prevent molten metal from being stuck to the sand, i.e. seizure, during casting. However, if an organic binder is added together with a ceramic binder as specified by the invention, such seizure can never take place, that is, the resulting sandmold has excellent anti-seizure property.
(4) In a sandmold set up by not only organic binder but also ceramic binder as specified by the invention, if fire-proof inorganic fine powder such as ` 13~078g silica, alumina, and zirconia is added beforehand to the sand as an anti-infiltration material together with the organic binder and the ceramic binder, particles of the inorganic fine powder block voids s between sand particles, and the fine powder particles and the sand particles become fused to be united together by the action of the ceramic binder when heated during casting, thereby further improving the anti-infiltration property of the resulting sandmold 10 such that infiltration of molten metal into the sand is fully prevented.
(5) A sandmold used for forming cast steel, special steel or the like requires to have particularly high casting strength and needs the use 15 of large amounts oE the above-mentioned anti-infiltration material such as sil.ica and high-temperature reineorcing material such as boric acid. However, as the amounts oE these additives are - increased, the moldability o the sand is degraded, 20 thus re~uiring a larger amount of binder. However, the use of an increased amount of binder leads to an increase in the production cost as well as a decrease in the breakableness or disintegrableness of the sandmold. However, iE a viscosity adjuster such as 25 saccharildçs and dextrin is added to the sand, the ~ mo~a,b,',~, ~y A me~Rb~ q~of the sand is enhanced without lncreasing the amount of binder, while maintaining sufficient breakableness of the sandmold.
(6) In the manufacture of ductile cast iron, if 30 sulfuric compounds are present in the molten metal, spheroidization of graphitic carbon present in the cast iron is undesirably hindered by the sulfuric compounds. To be specific, in the case of manufacturing a sandmold by the use of an organic 3Q(~7~9 binder, sulfur components supplied from sulfuric acid and/or organic sulfonic acid, which are used for f~ran e curing self-setting phenol resin, urea-denatured-~e resin, etc. react with magnesium added to the molten metal for spheroidizing the graphitic carbon, to consume the magnesium and thus hinder the spheroidization of the graphitic carbon. To prevent this, a mold wash is conventionally applied to the inner walls of the sandmold. However, if a stabilizer of granular carbon such as ferrous oxide and magnesium oxide is added to the sand, the stabilizer reacts with the sulfuric compounds, thereby ensuring spheroidization of the graphitic carbon.
The present invention is based upon the above findings. The mold material for forming a sandmold according to the invention has the aforementioned chemical composition. Throughout the present specification percentages of the components are weight percentages.
The contents of the individual componen-ts of the mold material oE the present invention are limited as previously stated, for the following reasons:
(a) Organic Bi.nder:
Organic binders which can be used in the mold material of the present invention include resins such as furfuryl alcohol, phenol xesin, polyester resin, and also include resins obtained by denaturation or reaction of the above resins, e.g. urea-furane resin, phenol-furane resin, polyester-furane resin, phenol-isocyanate resin, and polyester-isocyanate resin. These synthetic resins are also conventionally employed in the manufacture of sandmolds as organic binders. These synthetic resins, if added to the sand and then cured, act to enhance the shelf strength of 131~0789 the resulting sandmold to thereby prevent seizure of the sand.
However, if the organic binder content is less than 0.4 percent, the above action to enhance the shelf strength cannot be performed to a satisfactory extent, and on the other hand, if it exceeds 3.0 percent, it will result in degraded breakableness of the sandmold as well as in increased manufacturing cost due to increased organ-ic binder content. Therefore, the organic binder content has been limited to a range from 0.4 to 3.0 percent. The preferable range is from 0.4 to 2Ø
(b) Catalyst for Curing Organic Binder:
As the catalyst for curing organic binder can be employ-ed conventional catalysts, such as sulfuric acid, phosphoric acid, benzenesulfonlc acid, toluenesulfonic acid, xylenesulfonic acid, and isocyanate, preferably, diphenylmethane-4,4' diisocyanate (MDI), hexamethylelle diisocyanate (HDI), 2,4 toluene diisocyanate (2,4 TD~), 2,6 toluene diisocyanAte (2,6 TDI), and a mixture thereo. Besides these catalysts, all suitable materials conven-tionally used as the catalyst for curing organic binder may be employed as the catalyst for curing the organic binder in the present invention.
Generally, if the catalyst content is less than 0.2 percent, the organic binder in the sandmold is not cured or hard-ened to a sufficient extent, whereas if the catalyst content is larger than 2.0 percent, the curing speed is too high for the molding operation to be smoothly performed. Therefore, the ~3~
- 8a - 70668-14 catalyst content has been limited to a range from 0.2 to 2.0 percent. Best results can be obtained if the catalyst content is from 0.3 to 1.5.
(c) Ceramic Binder:
' '`;`
' :~ ' -`" '`'`'`'~' ;, "`
. ' ~
~ 3L3~
Ceramic binders which can be used in the mold material of the invention include silicate esters, hydrolyzed sili~ate esters, silica sol of alcohol dispersed type, and silica sol of water dispersed type. Preferred, silicate esters include ethyl silicate, methyl silicate, propyl silicate, butyl silicate, ~am~r thereof, llexamer thereof, and a mixture thereof. The ~ilicate esters can be easily hydrolyzed in an aqueous solution or in an acid-aqueous solution. A product formed by hydrolyzation of ester silicate in a sulfuric acid-aqueous solution containing alcohol may be used together with or in place of ester silicate.
~s the silica sol of water dispersed type or alcohol dispersed type may be used silica sol formed by silica in the form of fine powder having a grain size of 20 miarons or less and dispersed i.n an aqueous sol~ltion or alcohol such a ethano]. or an alcohol-aqueous æo:Lution. Such silica sol is sold on the market under reyistered trademar]c "A~ROSOL" from Nippon Aerosil Co., Ltd.
Further may also be used slliaa sol prepared from hlyhly dispersed amorphous silica haviny a mean yrain size of the order of 12 microns.
Fine granular silica supplled from these ceramic binders have such a property that they act to sinter the sand wherein sand particles are combined together, at temperatures from 800 to 850C, and they are melted at temperatures from 1000 to 1200C to firmly unike sand particles together. Thus, these silicas act very excellently at hlgh temperatures to grea~ly improve the casting strength of the sandmold and also prevent infiltration of molten metal into the sand in cooperation with anti-infiltration material, hereinafter referred to, thereby enabling omission of -` 3L3V`~
the mold washin~ operation or slmplifying the same operation. If the silica content in the ceramic binder~s) is less than 0.05 percent, the above action cannot be performed with satisfactory results, and on the other hand, if the silica content exceeds 2.0 percent, it can cause a degradation in the breakableness of the sandmold. Therefore, the ceramic binder content has been limited to a range from 0.1 to 2.0 percent in terms of the silica content.
Best results can be obtained if the ceramic content in terms of the silica content is from 0.1 to 1Ø
td) Catalyst for Curing Ceramic Binder:
Alcohol componen~, alcohol and water, and water or alcohol, which are contained, respectively, in the silicate ester, hydroly~ed silicate ester, and the silica sol, used as the ceramic billder in the invention, act to decrease the curin~ speed of the organic binder and also reduce the shelf strength of the sandmold.
Therefore, a~cordln~ to the invention isocyanate is added in order to remove suah alcohol and water contained in the ceramic binder so as to increase the curin~ speed of the organlc binder and the shelf stren~th of the sandmold. As the isocyanate, any kind of isocyanate can be used insofar as it can react with various kinds of alcohol or water to perform the above-mentioned action:
preferably, diisocyanate, and particularly diphenylmethane-4, ~'diisocyanate (MDI), hexamethylene diisocyanate (HD~), 2,4 toluene diisocyanate (2,4 TDI), 2,6 toluene diisocyanate (2,6 ~; TDI), and a mixture thereof may be advantageously used.
If the isocyanate content is less than 0.05 percent, the above action cannot be performed to a sufficient extent, whereas even if it exceeds 20 A ~ ~
`:~1~ `
7a i~
percent r no better results is obtained, even causing an increase in the production cost. Therefore, the catalyst content has been limited to a range from 0.05 to 2.0 percent.
The preferable range is from 0.1 to 1.5.
Foundry sand:
The foundry sand preferably has a grain size of 325 mesh or less.
(e) Anti-infliltration Material:
The fire-proof powder used in the invention is an additive effective to block voids between sand particles, thereby serving to further prevent the molten metal from infiltratin~ into the ~andmold in cooperation with the ceramic binder Oe the invention, as stated before. The fire-proof powder pre~erably includes silica, alumina, and zirconia, all having a grain size oE the order of 10-30 microns. If added in less than 0.1 percent, sufficient anti-infiltration results cannot be obtained, whereas in excess of 3.0 percent, it will result in degraded shelf strength of the sandmold. This is why the content of the fire-proof powder has been limited to a range from 0.1 to 3.0 percent. Best results can be obtained if the content is from 0.5 to 2Ø
(f) High-temperature Reinforcing ~aterial:
Particularly hlgh casting strength is required of a sandmold for casting metal of which the molten metal temperature is relatively high, such as cast steel and special steel. To satisfy this requirement, the sandmold should he reinforced by a material which melts at the temperature of t~ .
`~ ~3~
: - lla - 70668-14 molten metal being poured into the sandmold, to cause sand particles, binders and other add.itives to be firmly united together. Such material, i.e. high-temperature reinforcing material may be added according to necessity, and preferably common salt, boric acid, and borax may be used as the reinforc-ing material. If added in less :
. ~
13~C~7~39 than 0.1 percent, the above-mentioned results cannot be satisfactorily achieved, whereas in excess of 3.0 percent, the breakableness of the sandmold will be degraded. Therefore, the reinforcing material content has been limited to a range from 0.1 to 3.0 percent, and preferably, from 0.3 to 2Ø
tg) Viscosity Adjuster:
A sandmold for casting cast steel, special steel or the like has to have specially high high-temperature strength. However, if the binder contentis increased so as to enhance the moldability of the sandmold, it will degrade the breakableness of the sandmold. On the contrary, if the additive amount of the high-temperature reinforcing material as mentioned IS above is increased so as to increase the casting strength of the sandmold, it will degrade the moldability ~f the sandmold. Irherefore, if it is desired to enhance the moldability of the sandmold without degrading the breakableness and the casting streng~.ht a viscosity adjuster such as saccharides, e.g. molasses, and dextrin may be added. However, if the adjuster content is less than 0.1 percent, the adjuster cannot fully exhibit its proper function of enhancing the moldability, whereas in excess of 2.0 percent, it will result in degraded shelf strength of the sandmold. This is why the adjuster content has been limited to a range from 0.1 to 2.0 percent, and preferably from 0.3 to 1.5.
(h) Granular Carbon Stabilizer:
Ferrous oxide and magnesium oxide react with sulfuric compounds supplied from the catalyst for curing organic binder, etc. to combine with the sulfuric compounds. Therefore, if fine powders of ferrous oxide and/or magnesium oxide are added to the ~ ~3~
sand, they will act to prevent the sulfuric compounds from being mixed into the casting product, thus ensuring spheroidization of graphitic carbon in ductile cast iron to be produced. Therefore, according to the invention, in manufacturing a sandmold for casting ductile cast steel, for instance, a granular carbon stabilizer constituted by an inorganic material in the form of fine powder, preferably, one or both of ferrous oxide powder and magnesium oxide, is added according to necessity. If the s-tabilizer content is less than 0.03 percent, the stabilizer cannot perform its stabilizing action to a full extent, whereas a stabilizer content in excess of 0.5 percent will not contribute to further enhancing the above action, but will rather result in increased production cost. Thus, the stabilizer content has been limited to a range from 0.03 to 0.5 percent, and pre~erably, rom 0.1 to 0.4.
E~AMPLE
An example oE the invention will now be described in comparison with comparative examples.
First prepared were the following materials in order to obtain sandmolds Nos. 1 - 13 and 1" ~ 13"
formed by mold materials according to the present invention, as well as comparative sandmolds Nos. 1 and 2 formed by conventional mold materials. In Tables I
and II given below, the components constituting the mold materials are indicated by respective alphabetical symbols with numerals which are parenthesized hereinbelow, the numerals representing kinds of the component:
(a)~ rganic Binder (R) A I ~ alcohol (R-l), phenol resin (R-2), ~ 4 70668-1 urea-furane resîn (R-3), polyester-furane resin (R-4), phenol-furane resin (R-5), alkyd resin (R-6), phenol (urethane type) resin (R-7), and polyester resin (R-8).
(b) Catalyst for Organic Rinder (RC) P-toluenesulfonic. acid (RC-l), xylenesulfonic acid (RC-2), benzenesulfonic acid (RC-3), diphenylmethane-4,4' diisocyanate (RC-4), 2,4 toluene diisocyanate (RC-5), 2,6 toluene diisocyanate (RC-6), and hexamethylene diisocyanate (RC-7).
(c) Ceramic Blnder (CB) Hydrolyzed methyl silicate (C~-l), hydrolyzed ethyl silicata (CB-2), hydrolyzed propyl silicate (CB-3), hydrolyzed butyl silicate (CB-4), silica sol of alcohol dispersed type (CB-5), and silica ~ol of water di~persed type (CB-6).
~d) Catalyst for Ceramic Binder (CC) Diphenyl methane-~4' diisoayanate (CC-l), 2,4 toluene diisocyanate (CC-2), 2,6 toluene diisocyanate (CC-3), and hexamethylene diisocyanate (CC-4).
(e) Flre-Proof Powder (F) Silica having an average grain size oi 15 microns (F-l), alumina having an average grain size of 20 microns (F-2), and zircon having an average graln size o~ 25 microns (F-3).
: (f) Granular Carbon Stabilizer (CS) Magnesium oxide having an averaga grain size of 10 microns (CS-l), and ferrous oxide having an average grain size of 20 microns (CS-2).
(g) High-temperature Reinforcing Material ~H) .3Q0789 14a 70668-14 Boric acid having an average grain size of 10 microns (H-l), and borax having an average grain size of 20 microns (H-2).
(h) Viscosity Adjuster (V) Molasses (V-l), and dextrin (V-2).
(i) Foundry sand (S), having a grain size ranging from 28 to 280 mesh, wherein the sand of 150 mesh and more is contained in an amount from 12.5 to 13.5%, of which the grain finess number (AFS) is 61.2.
Silica sand (S-l), zircon sand (S-2), and chromite sand (S-3)-After preparing the above materials, the silica sand kept at a temperature of 25C was charged into a batch mixer.
During rotation of the mixer, the p-toluenesulEonic acid (RC-l) was added in an amount of 1.9% to the silica sand as a catalyst for the organic binder, and then the sand and the catalyst were agitated ~or 20 seconds. The urEuryl alcohol (R-l) was then added in an amount of 2.9% to the sand as an organic binder, fol-lowed by agitation for 20 seconds. The silica (F-l) was then added in an amount Oe 2.9% to the sand as a fire-proof powder, ~ollowed by agitation for 20 seconds. The hydrolyzed methyl sili-cate (CB-l) was added in an amount of 1.9~, as a ceramic binder and the mixture was agi-tated Eor 20 seconds, followed by further addition of the diphenyl methane-4,4' diisocyanate (CC-l) in an amount 1.9% as a catalyst for the ceramic binder and subsequent agitation Eor 30 seconds. Immediately after the mixer was stop-; ped, the mold material thus kneaded was charged in an amount of 20kg into a space within a metallic flasX placed on a surface : `
"~
~00789 - 15a - 70668-14 plate, which space is defined between inner walls of the flask and a model disposed in the flask. The flask has an inside dimension of 210mm width, 290mm length, and 120mm height. After the lapse of a retention time of 1 hour, the resulting sandmold firmly set was : L3~
removed from the flask to obtain a sandmold No. 1 formed b~ a mold material according to the present inventiont which has a box-like configuration in the form of a truncated pyramid, having a recess of 5 truncated pyramid formed therein with a bottom surface size of 90mm X 150mm, a top surface size of 110mm X
160mm, and a height of 80mm.
Also, sandmolds Nos. 2 to 13, and 1" to 13"
formed by the inventive mold material were further 10 prepared in manners similar to the manner of preparing the sandmold No. 1 described above, by mixing the afore-specified materials in ratios as shown in Tables I and II. Incidentally, in sandmolds using dextrin and/or ferrous oxide as the viscosity adjuster and the 15 granular carbon stabiliæer, these components were added at the time of addition of the anti-infiltration material.
On the other hand, in order to obtain the comparative ~andmolds Nos. 1 and 2 Eormed by 20 conventional mold materials, the above-mentioned silica sand kept at a temperature oE 25C was charged into a high-speed sand mixer. During rotation of the mixer, p-toluenesulfonic acid was added in an amount o 0.5% to the sand, and the sand and acid were 25 agitated for 20 seconds, followed by addition of furane resin in an amount of 1.0% and further agitation for 30 seconds. ~fter stoppage of the A mixer, the mold material thus~k~eaded was charged in an amount of 20kg into the ~t~skh~ flask to obtain the 30 comparative sandmold No. 1 set up by the organic binder alone, which is of the same shape and dimensions as the sandmolds formed by the mold materials of the present invention.
Further, to obtain the comparative sandmold No. 2 l;~Q~7~39 set up by the ceramic bindar à~lone, the above-mentioned silica sand kept at 25C was charged into the high-speed sand mixer and agitated together with the sand. During rotation of the mixer, sodium silicate powder was added in an amount of 6% to the sand to be agitated together for 30 seconds. After stoppage of the the mixer, the mold material thus kneaded was charged in an amount of 20kg into the metallic flask and then cured by injecting C02 gas produced by a C02 gas producer, into the mold material. Then, the comparative sandmold No. 2 set up by the ceramic binder alone was obtained, which is of the same shape and dimensions as the sandmolds formed by the mold materials of the present invention.
Then, the sandmold Nos. l to 13 and l" to 13"
formed by the mold materials o the present invention as well as the comparative sandmolds Nos. l and 2 were tested in respect oE the ollowing properties:
Th~ sandmolds were tested in respect of shelf strength, i.e. r strength aEter being exposed to the atmosphere at room temperature for 2~ hours after formation thereoE, by the use of a penetration tester made by George Fischer Co., and the test results are shown in Tables I and II.
Further, in order to evaluate the anti-seizure property and anti-infiltration property, molten common-type cast iron having a temperature from 1250 to 1300C was poured into each of the sandmolds, without applying mold washing, to obtain castings each having a weight of 8.8kg. After being quenched, the castings thus obtained were subjected to shot blasting for removal of sand stuck on the surfaces. Then, the surfaces of the castings and the surfaces of the sandmolds were checked for seizure and inEiltration of the molten metal. The results are shown in Tables I
and II, in which sandmolds marked with ~ showed excellent anti-seizure pxoperty or anti-infriltration property, O good, and X poor, respectively.
I 5 In addition, in order to examine degree of spheroidization of ~ carbon in graphitic iron castings manufactured by sandmolds Nos. 2", 4"t and 8"
- 13", these sandmolds were additionally manufactured in the same manner as stated above~ After preparation of the sandmolds Nos. 2", 4", and 8" - 13", molten metal of common-type graphitic carbon cast iron was poured into the 5andmolds Nos. 2", ~" and 8" ~ 13" to obtain metal castings each having a weight of 8.8kg.
After being q~enched, the castings thus obtained were each broken, and the broken surfaces were checked to examine degree o spheroidization o graphitic carbon ln the castings.
Further, in order to evaluate the casting strength, cylindrical sandsmolds each having an outer diameter o lOOmm and a height of 150mm were also prepared, which correspond in material composition, respectively, to the above-mentioned sandmolds Nos. 1 to 13, and Nos. 1" to 13" and comparative sandmolds No. 1 and 2, in the same manners as described above.
The sandmolds thus prepared were exposed to the atmosphere kept at a temperature of 1000C in an electric furnace for 5 minutes. After being cooled, the cylindrical sandsmolds were each measured in respect of casting strength by the use of the above-mentioned penetration tester, the test results of which are also shown in Tables I and II.
As is apparent from Tables I and II, the sandmolds formed by the mold mat~rials of the present invention all showed superior values in both the shelf 13[)V~
strength and the casting stren~gth to the comparative sandmolds set up by furane resin alone. On the other hand, the comparative sandmold No. 2 set up by sodium silicate showed excellent anti-infiltration property but inferior shelf strength to the other sandmolds.
Further, it is noted from Tables that both the comparative sandmolds Nos. 1 and 2 require mold washing, since the former has degraded anti-infiltration property while the latter has degraded anti-seizure property. On the other hand, the sandmolds formed by the mold materials of the present invention are excellent in both anti-sei2ure property and anti-infiltration property, thereby providing excellent sandmolds which can exhibit satisfactory performance in actual use even without mold washing.
As for granular carbon stability, the sandmolds ormed ~y the mold materials of the present invention, to which the granular carbon stabilizer has been added, each provlded a metal casting which is excellent, i.e., marked with ~ , or good, i.e., marked with O , in granular carbon stability, as shown in Table I~.
The present invention is based upon the above findings. The mold material for forming a sandmold according to the invention has the aforementioned chemical composition. Throughout the present specification percentages of the components are weight percentages.
The contents of the individual componen-ts of the mold material oE the present invention are limited as previously stated, for the following reasons:
(a) Organic Bi.nder:
Organic binders which can be used in the mold material of the present invention include resins such as furfuryl alcohol, phenol xesin, polyester resin, and also include resins obtained by denaturation or reaction of the above resins, e.g. urea-furane resin, phenol-furane resin, polyester-furane resin, phenol-isocyanate resin, and polyester-isocyanate resin. These synthetic resins are also conventionally employed in the manufacture of sandmolds as organic binders. These synthetic resins, if added to the sand and then cured, act to enhance the shelf strength of 131~0789 the resulting sandmold to thereby prevent seizure of the sand.
However, if the organic binder content is less than 0.4 percent, the above action to enhance the shelf strength cannot be performed to a satisfactory extent, and on the other hand, if it exceeds 3.0 percent, it will result in degraded breakableness of the sandmold as well as in increased manufacturing cost due to increased organ-ic binder content. Therefore, the organic binder content has been limited to a range from 0.4 to 3.0 percent. The preferable range is from 0.4 to 2Ø
(b) Catalyst for Curing Organic Binder:
As the catalyst for curing organic binder can be employ-ed conventional catalysts, such as sulfuric acid, phosphoric acid, benzenesulfonlc acid, toluenesulfonic acid, xylenesulfonic acid, and isocyanate, preferably, diphenylmethane-4,4' diisocyanate (MDI), hexamethylelle diisocyanate (HDI), 2,4 toluene diisocyanate (2,4 TD~), 2,6 toluene diisocyanAte (2,6 TDI), and a mixture thereo. Besides these catalysts, all suitable materials conven-tionally used as the catalyst for curing organic binder may be employed as the catalyst for curing the organic binder in the present invention.
Generally, if the catalyst content is less than 0.2 percent, the organic binder in the sandmold is not cured or hard-ened to a sufficient extent, whereas if the catalyst content is larger than 2.0 percent, the curing speed is too high for the molding operation to be smoothly performed. Therefore, the ~3~
- 8a - 70668-14 catalyst content has been limited to a range from 0.2 to 2.0 percent. Best results can be obtained if the catalyst content is from 0.3 to 1.5.
(c) Ceramic Binder:
' '`;`
' :~ ' -`" '`'`'`'~' ;, "`
. ' ~
~ 3L3~
Ceramic binders which can be used in the mold material of the invention include silicate esters, hydrolyzed sili~ate esters, silica sol of alcohol dispersed type, and silica sol of water dispersed type. Preferred, silicate esters include ethyl silicate, methyl silicate, propyl silicate, butyl silicate, ~am~r thereof, llexamer thereof, and a mixture thereof. The ~ilicate esters can be easily hydrolyzed in an aqueous solution or in an acid-aqueous solution. A product formed by hydrolyzation of ester silicate in a sulfuric acid-aqueous solution containing alcohol may be used together with or in place of ester silicate.
~s the silica sol of water dispersed type or alcohol dispersed type may be used silica sol formed by silica in the form of fine powder having a grain size of 20 miarons or less and dispersed i.n an aqueous sol~ltion or alcohol such a ethano]. or an alcohol-aqueous æo:Lution. Such silica sol is sold on the market under reyistered trademar]c "A~ROSOL" from Nippon Aerosil Co., Ltd.
Further may also be used slliaa sol prepared from hlyhly dispersed amorphous silica haviny a mean yrain size of the order of 12 microns.
Fine granular silica supplled from these ceramic binders have such a property that they act to sinter the sand wherein sand particles are combined together, at temperatures from 800 to 850C, and they are melted at temperatures from 1000 to 1200C to firmly unike sand particles together. Thus, these silicas act very excellently at hlgh temperatures to grea~ly improve the casting strength of the sandmold and also prevent infiltration of molten metal into the sand in cooperation with anti-infiltration material, hereinafter referred to, thereby enabling omission of -` 3L3V`~
the mold washin~ operation or slmplifying the same operation. If the silica content in the ceramic binder~s) is less than 0.05 percent, the above action cannot be performed with satisfactory results, and on the other hand, if the silica content exceeds 2.0 percent, it can cause a degradation in the breakableness of the sandmold. Therefore, the ceramic binder content has been limited to a range from 0.1 to 2.0 percent in terms of the silica content.
Best results can be obtained if the ceramic content in terms of the silica content is from 0.1 to 1Ø
td) Catalyst for Curing Ceramic Binder:
Alcohol componen~, alcohol and water, and water or alcohol, which are contained, respectively, in the silicate ester, hydroly~ed silicate ester, and the silica sol, used as the ceramic billder in the invention, act to decrease the curin~ speed of the organic binder and also reduce the shelf strength of the sandmold.
Therefore, a~cordln~ to the invention isocyanate is added in order to remove suah alcohol and water contained in the ceramic binder so as to increase the curin~ speed of the organlc binder and the shelf stren~th of the sandmold. As the isocyanate, any kind of isocyanate can be used insofar as it can react with various kinds of alcohol or water to perform the above-mentioned action:
preferably, diisocyanate, and particularly diphenylmethane-4, ~'diisocyanate (MDI), hexamethylene diisocyanate (HD~), 2,4 toluene diisocyanate (2,4 TDI), 2,6 toluene diisocyanate (2,6 ~; TDI), and a mixture thereof may be advantageously used.
If the isocyanate content is less than 0.05 percent, the above action cannot be performed to a sufficient extent, whereas even if it exceeds 20 A ~ ~
`:~1~ `
7a i~
percent r no better results is obtained, even causing an increase in the production cost. Therefore, the catalyst content has been limited to a range from 0.05 to 2.0 percent.
The preferable range is from 0.1 to 1.5.
Foundry sand:
The foundry sand preferably has a grain size of 325 mesh or less.
(e) Anti-infliltration Material:
The fire-proof powder used in the invention is an additive effective to block voids between sand particles, thereby serving to further prevent the molten metal from infiltratin~ into the ~andmold in cooperation with the ceramic binder Oe the invention, as stated before. The fire-proof powder pre~erably includes silica, alumina, and zirconia, all having a grain size oE the order of 10-30 microns. If added in less than 0.1 percent, sufficient anti-infiltration results cannot be obtained, whereas in excess of 3.0 percent, it will result in degraded shelf strength of the sandmold. This is why the content of the fire-proof powder has been limited to a range from 0.1 to 3.0 percent. Best results can be obtained if the content is from 0.5 to 2Ø
(f) High-temperature Reinforcing ~aterial:
Particularly hlgh casting strength is required of a sandmold for casting metal of which the molten metal temperature is relatively high, such as cast steel and special steel. To satisfy this requirement, the sandmold should he reinforced by a material which melts at the temperature of t~ .
`~ ~3~
: - lla - 70668-14 molten metal being poured into the sandmold, to cause sand particles, binders and other add.itives to be firmly united together. Such material, i.e. high-temperature reinforcing material may be added according to necessity, and preferably common salt, boric acid, and borax may be used as the reinforc-ing material. If added in less :
. ~
13~C~7~39 than 0.1 percent, the above-mentioned results cannot be satisfactorily achieved, whereas in excess of 3.0 percent, the breakableness of the sandmold will be degraded. Therefore, the reinforcing material content has been limited to a range from 0.1 to 3.0 percent, and preferably, from 0.3 to 2Ø
tg) Viscosity Adjuster:
A sandmold for casting cast steel, special steel or the like has to have specially high high-temperature strength. However, if the binder contentis increased so as to enhance the moldability of the sandmold, it will degrade the breakableness of the sandmold. On the contrary, if the additive amount of the high-temperature reinforcing material as mentioned IS above is increased so as to increase the casting strength of the sandmold, it will degrade the moldability ~f the sandmold. Irherefore, if it is desired to enhance the moldability of the sandmold without degrading the breakableness and the casting streng~.ht a viscosity adjuster such as saccharides, e.g. molasses, and dextrin may be added. However, if the adjuster content is less than 0.1 percent, the adjuster cannot fully exhibit its proper function of enhancing the moldability, whereas in excess of 2.0 percent, it will result in degraded shelf strength of the sandmold. This is why the adjuster content has been limited to a range from 0.1 to 2.0 percent, and preferably from 0.3 to 1.5.
(h) Granular Carbon Stabilizer:
Ferrous oxide and magnesium oxide react with sulfuric compounds supplied from the catalyst for curing organic binder, etc. to combine with the sulfuric compounds. Therefore, if fine powders of ferrous oxide and/or magnesium oxide are added to the ~ ~3~
sand, they will act to prevent the sulfuric compounds from being mixed into the casting product, thus ensuring spheroidization of graphitic carbon in ductile cast iron to be produced. Therefore, according to the invention, in manufacturing a sandmold for casting ductile cast steel, for instance, a granular carbon stabilizer constituted by an inorganic material in the form of fine powder, preferably, one or both of ferrous oxide powder and magnesium oxide, is added according to necessity. If the s-tabilizer content is less than 0.03 percent, the stabilizer cannot perform its stabilizing action to a full extent, whereas a stabilizer content in excess of 0.5 percent will not contribute to further enhancing the above action, but will rather result in increased production cost. Thus, the stabilizer content has been limited to a range from 0.03 to 0.5 percent, and pre~erably, rom 0.1 to 0.4.
E~AMPLE
An example oE the invention will now be described in comparison with comparative examples.
First prepared were the following materials in order to obtain sandmolds Nos. 1 - 13 and 1" ~ 13"
formed by mold materials according to the present invention, as well as comparative sandmolds Nos. 1 and 2 formed by conventional mold materials. In Tables I
and II given below, the components constituting the mold materials are indicated by respective alphabetical symbols with numerals which are parenthesized hereinbelow, the numerals representing kinds of the component:
(a)~ rganic Binder (R) A I ~ alcohol (R-l), phenol resin (R-2), ~ 4 70668-1 urea-furane resîn (R-3), polyester-furane resin (R-4), phenol-furane resin (R-5), alkyd resin (R-6), phenol (urethane type) resin (R-7), and polyester resin (R-8).
(b) Catalyst for Organic Rinder (RC) P-toluenesulfonic. acid (RC-l), xylenesulfonic acid (RC-2), benzenesulfonic acid (RC-3), diphenylmethane-4,4' diisocyanate (RC-4), 2,4 toluene diisocyanate (RC-5), 2,6 toluene diisocyanate (RC-6), and hexamethylene diisocyanate (RC-7).
(c) Ceramic Blnder (CB) Hydrolyzed methyl silicate (C~-l), hydrolyzed ethyl silicata (CB-2), hydrolyzed propyl silicate (CB-3), hydrolyzed butyl silicate (CB-4), silica sol of alcohol dispersed type (CB-5), and silica ~ol of water di~persed type (CB-6).
~d) Catalyst for Ceramic Binder (CC) Diphenyl methane-~4' diisoayanate (CC-l), 2,4 toluene diisocyanate (CC-2), 2,6 toluene diisocyanate (CC-3), and hexamethylene diisocyanate (CC-4).
(e) Flre-Proof Powder (F) Silica having an average grain size oi 15 microns (F-l), alumina having an average grain size of 20 microns (F-2), and zircon having an average graln size o~ 25 microns (F-3).
: (f) Granular Carbon Stabilizer (CS) Magnesium oxide having an averaga grain size of 10 microns (CS-l), and ferrous oxide having an average grain size of 20 microns (CS-2).
(g) High-temperature Reinforcing Material ~H) .3Q0789 14a 70668-14 Boric acid having an average grain size of 10 microns (H-l), and borax having an average grain size of 20 microns (H-2).
(h) Viscosity Adjuster (V) Molasses (V-l), and dextrin (V-2).
(i) Foundry sand (S), having a grain size ranging from 28 to 280 mesh, wherein the sand of 150 mesh and more is contained in an amount from 12.5 to 13.5%, of which the grain finess number (AFS) is 61.2.
Silica sand (S-l), zircon sand (S-2), and chromite sand (S-3)-After preparing the above materials, the silica sand kept at a temperature of 25C was charged into a batch mixer.
During rotation of the mixer, the p-toluenesulEonic acid (RC-l) was added in an amount of 1.9% to the silica sand as a catalyst for the organic binder, and then the sand and the catalyst were agitated ~or 20 seconds. The urEuryl alcohol (R-l) was then added in an amount of 2.9% to the sand as an organic binder, fol-lowed by agitation for 20 seconds. The silica (F-l) was then added in an amount Oe 2.9% to the sand as a fire-proof powder, ~ollowed by agitation for 20 seconds. The hydrolyzed methyl sili-cate (CB-l) was added in an amount of 1.9~, as a ceramic binder and the mixture was agi-tated Eor 20 seconds, followed by further addition of the diphenyl methane-4,4' diisocyanate (CC-l) in an amount 1.9% as a catalyst for the ceramic binder and subsequent agitation Eor 30 seconds. Immediately after the mixer was stop-; ped, the mold material thus kneaded was charged in an amount of 20kg into a space within a metallic flasX placed on a surface : `
"~
~00789 - 15a - 70668-14 plate, which space is defined between inner walls of the flask and a model disposed in the flask. The flask has an inside dimension of 210mm width, 290mm length, and 120mm height. After the lapse of a retention time of 1 hour, the resulting sandmold firmly set was : L3~
removed from the flask to obtain a sandmold No. 1 formed b~ a mold material according to the present inventiont which has a box-like configuration in the form of a truncated pyramid, having a recess of 5 truncated pyramid formed therein with a bottom surface size of 90mm X 150mm, a top surface size of 110mm X
160mm, and a height of 80mm.
Also, sandmolds Nos. 2 to 13, and 1" to 13"
formed by the inventive mold material were further 10 prepared in manners similar to the manner of preparing the sandmold No. 1 described above, by mixing the afore-specified materials in ratios as shown in Tables I and II. Incidentally, in sandmolds using dextrin and/or ferrous oxide as the viscosity adjuster and the 15 granular carbon stabiliæer, these components were added at the time of addition of the anti-infiltration material.
On the other hand, in order to obtain the comparative ~andmolds Nos. 1 and 2 Eormed by 20 conventional mold materials, the above-mentioned silica sand kept at a temperature oE 25C was charged into a high-speed sand mixer. During rotation of the mixer, p-toluenesulfonic acid was added in an amount o 0.5% to the sand, and the sand and acid were 25 agitated for 20 seconds, followed by addition of furane resin in an amount of 1.0% and further agitation for 30 seconds. ~fter stoppage of the A mixer, the mold material thus~k~eaded was charged in an amount of 20kg into the ~t~skh~ flask to obtain the 30 comparative sandmold No. 1 set up by the organic binder alone, which is of the same shape and dimensions as the sandmolds formed by the mold materials of the present invention.
Further, to obtain the comparative sandmold No. 2 l;~Q~7~39 set up by the ceramic bindar à~lone, the above-mentioned silica sand kept at 25C was charged into the high-speed sand mixer and agitated together with the sand. During rotation of the mixer, sodium silicate powder was added in an amount of 6% to the sand to be agitated together for 30 seconds. After stoppage of the the mixer, the mold material thus kneaded was charged in an amount of 20kg into the metallic flask and then cured by injecting C02 gas produced by a C02 gas producer, into the mold material. Then, the comparative sandmold No. 2 set up by the ceramic binder alone was obtained, which is of the same shape and dimensions as the sandmolds formed by the mold materials of the present invention.
Then, the sandmold Nos. l to 13 and l" to 13"
formed by the mold materials o the present invention as well as the comparative sandmolds Nos. l and 2 were tested in respect oE the ollowing properties:
Th~ sandmolds were tested in respect of shelf strength, i.e. r strength aEter being exposed to the atmosphere at room temperature for 2~ hours after formation thereoE, by the use of a penetration tester made by George Fischer Co., and the test results are shown in Tables I and II.
Further, in order to evaluate the anti-seizure property and anti-infiltration property, molten common-type cast iron having a temperature from 1250 to 1300C was poured into each of the sandmolds, without applying mold washing, to obtain castings each having a weight of 8.8kg. After being quenched, the castings thus obtained were subjected to shot blasting for removal of sand stuck on the surfaces. Then, the surfaces of the castings and the surfaces of the sandmolds were checked for seizure and inEiltration of the molten metal. The results are shown in Tables I
and II, in which sandmolds marked with ~ showed excellent anti-seizure pxoperty or anti-infriltration property, O good, and X poor, respectively.
I 5 In addition, in order to examine degree of spheroidization of ~ carbon in graphitic iron castings manufactured by sandmolds Nos. 2", 4"t and 8"
- 13", these sandmolds were additionally manufactured in the same manner as stated above~ After preparation of the sandmolds Nos. 2", 4", and 8" - 13", molten metal of common-type graphitic carbon cast iron was poured into the 5andmolds Nos. 2", ~" and 8" ~ 13" to obtain metal castings each having a weight of 8.8kg.
After being q~enched, the castings thus obtained were each broken, and the broken surfaces were checked to examine degree o spheroidization o graphitic carbon ln the castings.
Further, in order to evaluate the casting strength, cylindrical sandsmolds each having an outer diameter o lOOmm and a height of 150mm were also prepared, which correspond in material composition, respectively, to the above-mentioned sandmolds Nos. 1 to 13, and Nos. 1" to 13" and comparative sandmolds No. 1 and 2, in the same manners as described above.
The sandmolds thus prepared were exposed to the atmosphere kept at a temperature of 1000C in an electric furnace for 5 minutes. After being cooled, the cylindrical sandsmolds were each measured in respect of casting strength by the use of the above-mentioned penetration tester, the test results of which are also shown in Tables I and II.
As is apparent from Tables I and II, the sandmolds formed by the mold mat~rials of the present invention all showed superior values in both the shelf 13[)V~
strength and the casting stren~gth to the comparative sandmolds set up by furane resin alone. On the other hand, the comparative sandmold No. 2 set up by sodium silicate showed excellent anti-infiltration property but inferior shelf strength to the other sandmolds.
Further, it is noted from Tables that both the comparative sandmolds Nos. 1 and 2 require mold washing, since the former has degraded anti-infiltration property while the latter has degraded anti-seizure property. On the other hand, the sandmolds formed by the mold materials of the present invention are excellent in both anti-sei2ure property and anti-infiltration property, thereby providing excellent sandmolds which can exhibit satisfactory performance in actual use even without mold washing.
As for granular carbon stability, the sandmolds ormed ~y the mold materials of the present invention, to which the granular carbon stabilizer has been added, each provlded a metal casting which is excellent, i.e., marked with ~ , or good, i.e., marked with O , in granular carbon stability, as shown in Table I~.
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Claims (24)
1. A mold material for forming sandmolds, consisting essen-tially of:
(a) an organic binder formed of a synthetic resin in an amount of 0.4 - 3.0 percent;
(b) a catalyst for curing the synthetic resin in an amount of 0.2 - 2.0 percent;
(c) a ceramic binder formed of at least one material selected from the group consisting of silicate esters, hydrolyzed silicate esters, silica sol dispersed in alcohol, and silica sol dispersed in water in an amount of 0.05 - 2.0 percent in terms of SiO2;
(d) a catalyst for curing the ceramic binder in an amount of 0.05 - 2.0 percent; and foundry sand being the balance.
(a) an organic binder formed of a synthetic resin in an amount of 0.4 - 3.0 percent;
(b) a catalyst for curing the synthetic resin in an amount of 0.2 - 2.0 percent;
(c) a ceramic binder formed of at least one material selected from the group consisting of silicate esters, hydrolyzed silicate esters, silica sol dispersed in alcohol, and silica sol dispersed in water in an amount of 0.05 - 2.0 percent in terms of SiO2;
(d) a catalyst for curing the ceramic binder in an amount of 0.05 - 2.0 percent; and foundry sand being the balance.
2. A mold material as claimed in claim 1, further including anti-infiltration fire-proof powder in an amount of 0.1 - 3.0 percent.
3. A mold material as claimed in claim 1, further including a high-temperature reinforcing material selected from the group consisting of common salt, borax, and boric acid in an amount of 0.1 - 3.0 percent.
4. A mold material as claimed in claim 1, further including a viscosity adjuster selected from the group consisting of saccha-rides and dextrin in an amount of 0.1 - 2.0 percent.
5. A mold material as claimed in claim 1, further including a granular carbon stabilizer formed of at least one material selected from the group consisting of ferrous oxide and magnesium oxide in an amount of 0.03 - 0.5 percent.
6. A mold material as claimed in claim 1, wherein the organic binder is selected from the group consisting of furfuryl alcohol, phenol resin, polyester resin, urea-furane resin, phenol-furane resin, polyester-furane resin, phenol-isocyanate resin, and polyester-isocyanate resin.
7. A mold material as claimed in claim 1, wherein the catalyst for curing the organic binder is formed of at least one material selected from the group consisting of sulfuric acid, phosphoric acid, benzenesulfonic acid, toluenesulfonic acid, xylenesulfonic acid, and isocyanate, diphenylmethane-4,4' diisocyanate (MDI), hexamethylene diisocyanate (HDI), 2,4 toluene diisocyanate (2,4 TDI) r and 2,6 toluene diisocyanate (2,6 TDI).
8. A mold material as claimed in claim 1, wherein the ceramic binder is selected from the group consisting of ethyl silicate, methyl silicate, propyl silicate, butyl silicate, and polymers produced by hydrolysis thereof.
9. A mold material as claimed in any one of claim 1 to 6, wherein the catalyst for curing the ceramic binder is formed of an isocyanate.
10. A mold material as claimed in claim 9, wherein the isocyanate is formed of at least one material selected from the group consisting of diphenylmethane-4,4' diisocyanate (MDI), hexamethylene diisocyanate (HDI), 2,4 toluene diisocyanate (2,4 TDI), and 2,6 toluene diisocyanate (2,6 TDI).
11. A mold material as claimed in claim 2, wherein the anti-infiltration fire-proof powder is formed of at least one material selected from the group consisting of silica, alumina, and zirconia.
12. A mold material as claimed in claim 1, wherein the foundry sand has a grain size of 325 mesh or less.
13. A mold material as claimed in claim 2, wherein the anti-infiltration fire-proof powder has a grain size from 10 to 30 microns.
14. A mold material as claimed in claim 6, wherein the catalyst for curing the organic binder is formed of at least one material selected from the group consisting of sulfuric acid, phosphoric acid, benzenesulfonic acid, toluenesulfonic acid, xylenesulfonic acid, and isocyanate, diphenylmethane-4,4' diisocyanate (MDI), hexamethylene diisocyanate (HDI), 2,4 toluene diisocyanate (2,4 TDI), and 2,6 toluene diisocyanate (2,6 TDI).
15. A mold material as claimed in claim 6 or 7, wherein the ceramic binder is selected from the group consisting of ethyl silicate, methyl silicate, propyl silicate, butyl silicate, and polymers produced by hydrolysis thereof.
16. A mold material as claimed in claim 6, 7 or 8, wherein the catalyst for curing the ceramic binder is formed of an isocyanate.
17. A method thereby forming a sandmold for manufacturing metal castings which comprises:
[i] mixing (a) an organic binder formed of a synthetic resin in an amount of 0.4 - 3.0 percent;
(b) a catalyst for curing the synthetic resin in an amount of 0.2 - 2.0 percent;
(c) a ceramic binder formed of at least one material selected from the group consisting of silicate esters, hydrolyzed silicate esters, silica sol dispersed in alcohol, and silica sol dispersed in water in an amount of 0.05 - 2.0 percent in terms of SiO2;
(d) a catalyst for curing the ceramic binder in an amount of 0.05 -2.0 percent; and foundry sand being the balance, [ii] charging the resulting mixture into a flask and setting the mixture at room temperature, and [iii] removing the set molding from the flask, thereby, forming a sandmold for manufacturing metal castings.
[i] mixing (a) an organic binder formed of a synthetic resin in an amount of 0.4 - 3.0 percent;
(b) a catalyst for curing the synthetic resin in an amount of 0.2 - 2.0 percent;
(c) a ceramic binder formed of at least one material selected from the group consisting of silicate esters, hydrolyzed silicate esters, silica sol dispersed in alcohol, and silica sol dispersed in water in an amount of 0.05 - 2.0 percent in terms of SiO2;
(d) a catalyst for curing the ceramic binder in an amount of 0.05 -2.0 percent; and foundry sand being the balance, [ii] charging the resulting mixture into a flask and setting the mixture at room temperature, and [iii] removing the set molding from the flask, thereby, forming a sandmold for manufacturing metal castings.
18. A method according to claim 17, which comprises:
pouring molten cast iron into the sandmold formed by the method of claim 17, and quenching the cast iron, thereby forming a metal casting.
pouring molten cast iron into the sandmold formed by the method of claim 17, and quenching the cast iron, thereby forming a metal casting.
19. A method as claimed in claim 18, wherein the molten cast iron is poured into the sandmold without washing with a mold wash material.
20. A method as claimed in claim 19, wherein the ceramic binder is selected from the group consisting of ethyl silicate, methyl silicate, propyl silicate, butyl silicate, and polymers produced by hydrolysis thereof.
21. A mold material as claimed in claim 7, wherein the organic binder is selected from the group consisting of furfuryl alcohol, phenol resin, polyester resin, urea-furane resin, phenol-furane resin, polyester-furane resin, phenol-isocyanate resin, and polyester-isocyanate resin, the ceramic binder is a member selected from the group consisting of ethyl silicate, methyl silicate, propyl silicate, butyl silicate, and polymers produced by hydrolysis thereof; and the catalyst for curing the ceramic binder is an isocyanate.
22. A mold material as claimed in claim 21, wherein the organic binder is in an amount from 0.4 to 2.0 percent;
the catalyst for curing the synthetic resin is in an amount of from 0.3 to 1.5 percent;
the ceramic binder is in an amount of from 0.1 to 1.0 percent in terms SiO2; and the catalyst for curing the ceramic binder is in an amount of from 0.1 to 1.5 percent.
the catalyst for curing the synthetic resin is in an amount of from 0.3 to 1.5 percent;
the ceramic binder is in an amount of from 0.1 to 1.0 percent in terms SiO2; and the catalyst for curing the ceramic binder is in an amount of from 0.1 to 1.5 percent.
23. A mold material as claimed in claim 22 which further comprises:
an anti-infiltration fire-proof powder selected from the group consisting of silica, alumina and zirconia having a grain size of from 10 to 20 microns in an amount of from 0.5 to 2.0 percent;
a high temperature reinforcing material selected from the group consisting of common salt, borax and boric acid in an amount of from 0.3 to 2.0 percent; and a viscosity adjuster selected from the group consisting of saccharides and dextrin in an amount of from 0.3 to 1.5 percent; and wherein the foundry sand has a grain size of 325 mesh or less.
an anti-infiltration fire-proof powder selected from the group consisting of silica, alumina and zirconia having a grain size of from 10 to 20 microns in an amount of from 0.5 to 2.0 percent;
a high temperature reinforcing material selected from the group consisting of common salt, borax and boric acid in an amount of from 0.3 to 2.0 percent; and a viscosity adjuster selected from the group consisting of saccharides and dextrin in an amount of from 0.3 to 1.5 percent; and wherein the foundry sand has a grain size of 325 mesh or less.
24. A mold material as claimed in claim 23 which also contains a granular carbon stabilizer selected from the group consisting of ferrous oxide and magnesium oxide in amount of from 0.1 to 0.4 percent.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 535453 CA1300789C (en) | 1987-04-24 | 1987-04-24 | Mold material for forming sandmold without requiring mold wash |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 535453 CA1300789C (en) | 1987-04-24 | 1987-04-24 | Mold material for forming sandmold without requiring mold wash |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1300789C true CA1300789C (en) | 1992-05-12 |
Family
ID=4135489
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 535453 Expired CA1300789C (en) | 1987-04-24 | 1987-04-24 | Mold material for forming sandmold without requiring mold wash |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1300789C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114653892A (en) * | 2022-03-08 | 2022-06-24 | 内蒙古华泽装备制造有限公司 | Preparation method of ceramic/cast iron composite ingot mold and ceramic/cast iron composite ingot mold |
-
1987
- 1987-04-24 CA CA 535453 patent/CA1300789C/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114653892A (en) * | 2022-03-08 | 2022-06-24 | 内蒙古华泽装备制造有限公司 | Preparation method of ceramic/cast iron composite ingot mold and ceramic/cast iron composite ingot mold |
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