M - Foundry Additives Glossary
Is a refractory mineral called magnesium carbonate (MgCO3). It has some contaminants present, such as iron carbonate (FeCO3) and ferric oxide (Fe2O3) present. Its specific gravity is 3.1 and it is fused at 3929°F. (2165° C.). For foundry preparation and use it is a very valuable refractory aggregate particularly where basic refractories are required. Magnesite, when finely ground, is added to chrome sand mixtures as (MgO). MgO is also used as a foundry sand in certain mixtures. Where basic lined furnaces are in operation, dead burned magnesite is used. It is a hard, dense, granular material obtained by calcining magnesite rock at a temperature high enough to form a product inert to atmospheric moisture and carbon dioxide. It is chiefly magnesia (MgO) and is a basic refractory. In the casting of manganese steel, olivine sand or chromite Hevi-Sand containing 10% to 15% MgO addition is an excellent core sand base.
An oxidizing agent, MnO2, can be made synthetically or may be found as an ore, known as "bog manganese" or "wad." It has many uses in the foundry, one use being in core sand mixtures for oxidizing purposes. Small amounts are used, such as 0.25 percent.
MENHADEN OIL (See: CORE OIL-OILS)
An oil obtained by steaming or boiling fish caught along the U.S.A. Atlantic coast line. It is also called, "Porgy Oil," "Whitefish Oil," and in the South it is called, "Fatback" and "Moss Bunker." The oil contains 27% oleic acid, stearic acid and a few fats, so that it polymerizes as easily as vegetable oil used in core oils.
METALLIC SALTS (See: AMMONIUM NITRATE-DRIERS, CORE)
Are used as core oil driers (dryers). Some of the metallic salts added are those, such as: cobalt salt and iron salt, which function similarly to ammonium nitrate in core oil mixtures. If 100% of linseed oil is used, driers are not required. Metallic salts are only needed if polymers are in the core oil formula.
METHENAMINE (C6H12N4) (See: HEXA-HEXAMETHYLENE TETRAMINE)
METHOCEL (See: Methyl Cellulose)
Also known as "Methocel." It is prepared from cellulose fibers by treatment with an alkali and methyl chloride. It is used as either a white powder or as a granular form. It is soluble in cold water but insoluble in hot water. It is soluble in benzene, toluene, ethyl alcohol, and carbon tetrachloride. Methyl cellulose is used in the foundry industry as a thickening agent and film former in core or mold washes, sprays or coatings.
MICA (See: PARTING COMPOUND)
This is a group of minerals with monoclinic crystals which break off easily. Muscovite and biotite are the common varieties of mica used in certain foundry compounds, partings and coatings. Mica is called "a mineral facing" in the foundry. Mica is also called a "potash silicate" or a "potash mica" having the chemical composition [H2KA13(SiO,)J]. In the past, foundry people have known mica as "Isinglass." When used as a dry parting and dusted on the mold, it is often blended with graphite. It is an insulating mineral and is used as a covering for hot liquid metals to hold and maintain temperature. It is used as insulation in coating materials. The specific gravity of mica is 2.7 to 3.1. It has a Moh's hardness of 2 to 3. One (1) percent to two (2) percent addition has been used in non-ferrous molding sands for insulating purposes.
MINERAL FACING (See: DRY PARTING-MICA-PARTING COMPOUND)
Finely ground minerals, which pass the U.S. Standard Sieve No. 100 are called "flours." The mineral flours used in the foundry are those ground from silica, olivine, zircon, chromite, ceramic grog, graphite, silicates and others of minor importance.
MINERALIZER (See: IRON ORE OXIDE-IRON OXIDE-KLEAN SURF)
MINERAL OIL (See: CORE OIL-OILS)
MINERAL PARTING (See: MINERAL FLOUR-PARTINGS)
MODIFIED PHENOL-FORMALDEHYDE RESIN CATALYZED (See: RESINS)
Modified phenol-formaldehyde resin is synonymous with "modified phenolic resin." It is the product of the condensation reaction between phenol and formaldehyde which contains other co-reactants or resinous diluents in minor amounts. Usually it is modified with furfural or furfuryl alcohol. It is usually used as a hot-box resin binder, using an acid salt as the catalyst. Phosphoric acid or sulfuric acid are used as catalysts. Phenol resins used for shell molding, even though catalyzed with Hexa, do not cure until heat is supplied. This allows outside, commercially prepared sands to be coated and sold to the foundry industry.
MODIFIED PHENOLIC RESIN AND CATALYZED (See: RESINS)
Same as "modified phenol-formaldehyde, catalyzed." Phenol formaldehyde is unlike urea formadebyde as it is insoluble in water. Two catalysts are generally used with phenolic resins-phosphoric acid (H3P04) and paratoluene sulphonic acid (CH3C6H4SO3H). It is difficult to form copolymers between phenol formaldehyde and furfural. Reactions are slow under atmospheric conditions and reduced pressures employed in preparing modified resins.
MODIFIED RESINS (See: HOT BOX RESINS-RESINS)
Same as Hot Box resins, having various combinations of urea, phenol, furfuryl alcohol and other ingredients added to the base resin. Some urea resins are modified by furfuryl alcohol or furfural (for use as hot-box resins). Complex copolymers are formed, which when used as a binder with an acid catalyst grow in three dimensions to form infusible substances. With strong catalysts, like phosphoric acid, complete curing can be obtained in the cold state.
MODIFIED UREA RESINS (See: MODIFIED RESINS)
MOISTURE CONTENT (See: TEMPER WATER-WATER)
Water which is driven off by heating sand mixtures at 220°F. to 230°F. ( 105°C. to 10°C.).
MOLASSES (See: BINDERS-BONDS-CORE BINDERS)
The original standard quality for foundry use was called, "Blackstrap molasses." It has high solid content and was used in many core sand mixtures with water acting as a diluent. It is diluted about 10: 1 with water and used in blackings, core washes and mold sprays. It works well as an auxiliary binder in clay bonded sand mixtures for use as cores or molds.
MOLDING PLASTER (See: PLASTER OF PARIS)
MOLDING SAND (See: FOUNDRY SANDS)
Is that molding sand which is used as molds for the making of castings in the foundry. There is a variety of molding sands. They may be naturally bonded, unbonded, blended, compounded or formulated with clay bonds and additives. Most are "synthetic" (blended or formulated) molding sands. They vary throughout the country but almost every state possesses suitable molding sands for economical use in that given area. The finer the sands, the smoother the casting surface and each foundry specifies the type best suited for their operation. Molding sands may be termed "green," "dry," or "baked." They are referred to by other names such as backing, facing, system, floor, unit, side floor, etc. (Also see: FOUNDRY SANDS-NATURALLY BONDED SANDS-SANDS.)
MOLDING SAND-SYNTHETIC (See: MOLDING SAND-SAND, SYNTHETIC MOLDING)
MOLOCHITE (See: BRICK, CRUSHED-CALCINED CERAMIC GROG-CHAMOTTE-GROG)
This is an alumina-silica refractory. It has a high alumina content and the average chemical analysis used in the foundry is 50% to 55% silica (SiO2 ); 40% to 45% alumina (Al2O3); with 1.5% or less of the minor elements such as: titanium dioxide (TiO2 ); lime (CaO); soda (Na2O); and potash (K2O). Finely ground molochite is used in special shell or green sand molding mixtures. It is used as the refractory base in investment molding, as well as a base for some "precision casting" methods.
MOSS BUNKER (See: MENHADEN OIL)
This is a mineral rarely found in nature but widely created by artificially heating. It is a highly refractory material used for many purposes. Mullite is sometimes referred to as "Sillimanite" and "Andalusite," as they have the same composition. Artificial mullite has a composition of 3Al2O3 • 2SiO2• It is made by fusing a mixture of silica sand and bauxite in an electric furnace. Sillimanite and andalusite are found naturally but are also created by fusing a combination of ground alumina and silica at high temperatures. The Moh's hardness of these minerals is 6 to 7. Sillimanite is decomposed to mullite and silica when heated above 2826° F. ( 1555° C.).
MUSCOVITE (See: MICA)
MX VOLCLAY (See: VOLCLAY)
A granular, sized, practically dust-free, western (sodium) bentonite grade.
Review of "Glossary of Foundry Additives" by Clyde A. Sanders, American Colloid Company
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