US2056048A - Liquid parting product and method of applying same - Google Patents

Description

Patented Sept. 29, 1936 PATENT orFics aosao'st moum ra a'rma raonuc'r AND ammonor APPLYING SAME Andrew is. Gregory, White Plains, N. r" and -Eldrldige a. lay, Fair-field, Conn.

No wins. Application August 2t, 1934, s No, 241,994

molds for casting metals and which compositions,

are adapted to effect the clean separation at the 5 parting line of the surfaces of the respective cope and drag portions of the mold, as well as the clean separation of the sand from the surfaces of the wood, metal, composition or other patterns to which such parting is applied.

We are aware that in the preparation of sand molds for the casting of metals, dry powders having a silicious base, such as diatomaceous earth, tripoli or the like previously impregnated with an organic waterproofing substance such as tallow,

l5 stearic acid or rosin, have been commonly employed for dusting a pattern prior to the rlddling of the sand thereover in the formation of the desired mold. Also that it has been proposed, as set forth in Patent No. 1,866,278, to employ in the manufacture of such parting powdersa finely precipitated calcium carbonate base in lieu of the aforesaid silicious bases. The aforesaid parting powders containing a silicious base are objectionable because it is considered by many familiar with foundry practice that when inhaled into the lungs, they either render the-operative so inhaling the same susceptible to silicosis or they even constitute the direct cause thereof. Parting powders having a calcium carbonate base are objectionable, on the other hand, because the lime ingredient thereof appears to exert a fluxing action upon the silicious grains of the sand and effects the incipient fusion thereof, which action tends to cause occlusion of such fused sand particles in the surface of the casting and produces a so-called burn-on condition besides other surface defects v in the casting.

Our investigations have led to the discovery that it is possible to eliminate the objectionable features of such prior silicious or calcareous parting powders by the employment of what we term a liquid parting compound, which enables us to eliminate the health hazard when employing a silicious dust or the spoilage or loss of castings due to surface defects caused by the aforesaid ts, \rrv Et -163.5)

par, Japan or candelilla waxes or the like may be employed, provided the substance used and the amount thereof is not such as to leave a sticky residuum upon the evaporation of .the sol vent when the parting liquid is spread, or other- '5 wise applied, as a thin coating on the pattern or on the engaging sand surfaces of the cope and drag portions of the mold. Furthermore, in lieu of 5% of waterproofing substance, one may employ as low as 54 or as high as 20% thereof by 10 weight of the mixture, but where the percentage employed is very low, the time consumed in the application of the liquid to the pattern of the mold isv proportionately increased as a larger quantity thereof must be employed in such appliis cation thereof. For most purposes a percentage of such water-proofing composition between 2% and 10% by weight of the mixture is accordingly quite satisfactory and to be preferred.

Our improved composition is spread onto a m pattern and the mold then prepared by riddling the sand onto the pattern, then tamping the same and reversing the mold box and lifting the pattern. It will be found that a remarkably clean separation between the pattern and the sand surfaces of the resultant mold is obtained and furthermore, and in this respect our improved liquid parting differs materially from the dry parting powders heretofore employed, the liquid parting which is applied to such pattern will serve as a 30 residual waterproof film thereon upon the evaporation of the solvent, which enables such pattern to be used repeatedly, without a fresh sip-- plication of liquid parting thereto, for the prep aration of to 200 separate molds'of said pat- 35 tern. Ordinarily, as is well known, it isnecessary to dust the pattern with a dry parting powder each time the same is employed for the preparation of a mold.

Another advantage or our parting liquid, as 40 distinguished from a dry parting powder, resides in the fact that it is capable of being spread onto a pattern having uneven surfaces, such as small recesses, grooves or ribs thereon in such. a manner as to leave a substantially even film over the 45 I entire surface of the pattern and thereby the formation of undesirable fillets on the portions of the resultant casting produced in such mold corresponding to such small recesses, ribs or grooves can be entirely prevented, with the con- 50 sequence, that a remarkable faithful casting, in every way corresponding to the original pattern, can be expeditiously produced through the. employment of such a liquid parting in the preparation of a sand mold.

It is essential moreover, owing to the fire hazards in foundry operations, that the liquid vehicle or our improved parting should. comprise essentially a non-inflammable member of the group comprising dichlormethane, trichlorethylene, carbon tetrachloride, tetrachlorethane,

pentachlorethane, perchlorethylene and dichlor composition or in drying rate upon evaporation.

Where petroleum naphthas are employed as a diluent, it is desirable that the amount oi carbon tetrachloride should not exceed about 25% by weight of the liquid vehicle, but since these petroleum naphthas have a much slower evaporation rate than does carbon tetrachloride, they are not entirely satisfactory where there is a serious fire hazard since the degree of flammability of the mixed vehicle increases as the evaporation proceeds, it being non-inflammable at the moment of application of the liquid parting to the sand, which sand is frequently hot in ordinary practice, and the mixed vapors evolved being somewhat flammable toward the finish, after a few minutes have elapsed, owing to the substantially higher exaporation rate or the carbon tetrachloride content thereof.

It is imperative that the liquid vehicle have a high evaporation rate, so that the coating will dry on the pattern and on the sand surfaces of the cope and drag which engage each other, if applied to the latter surfaces, within a period not exceeding about five minutes, as otherwise the resultant delay in carrying out the usual operations performed in metal casting foundries is so serious as to render the liquid parting unacceptable. Qrdinary kerosene is not satisfactory for this purpose, not only because of its slow evaporation rate, but also it is not sufilciently noninflammable for use in the event the sand, to which it is applied, is hot and at a temperature in excess of the flash point of such kerosene, as is commonly the case in metal casting operations in foundries.

While our improved liquid parting may be ap- Filed as a thin coating, by means of a brush, to a pattern, it is preferable that the 'same be applied both to the pattern and to the meeting sand surfaces of the cope and drag of the mold by means of a spray gun or atomizer, as thereby a remarkably even and extremely thin coating can be applied to all portions of such pattern and mold as it is desired to coat without the possibility of any metal fillets being formed on the casting at undesirable points thereof.

After the coating has beenapplied to the pattern or to the sand surfaces of the cope or drag of the mold that are intended to engage each other, such coating is allowed to dry completely so as to form a relatively hard, as distinguished from sticky, coating on such pattern or on the individual particles of such sand surfaces to which it is applied and then the mold is formed in the usual manner, for example by riddling the sand onto the pattern as aforesaid. 7

Another advantage of our improved parting is that one or more patterns may be coated while isolated from the mold box and this feature permits of the group application of the liquid parting to such patterns by a single operative, a feature which is impossible when employing a dry parting powder. plied by coating 2. pattern with our improved liquid parting will remain on vertical or curved surfaces without shifting such as occurs where it is attempted to apply, a dry parting powder to such surfaces, and thus also the tendency for re metal fillets to be produced in undesirable locations on the casting is eliminated.

It is important-that the major portion of the wax or grease or resin employed be in solution in the mixture and not in a state ofsuspenslon as 15 in the case of the paint and varnish removers, containing volatile wax solvents, waxy compounds and a wax precipitant such as acetone or alcohol, as otherwise the evaporation of the liq-- uid from the applied coating will be excessively 29 retarded by a superficial him and the product will be rendered valueless for parting operations.

Our liquid parting is several times more efiicient than any dry parting powders when employed in metal casting operations, for example, 25

about 75 parts by weight of such liquid parting are capable of replacing 408 parts of dry parting powders. As a consequence, the shipping costs and storage space required. when employing the liquid product is considerably less than in the case of 39 such dry parting powders. Furthermore, owing to the fact that the liquid product is free from any decomposable carbonates and particularly magnesium carbonate, which frequently occurs as an impurity in the calcium carbonate base of parting 35 powders, such as herein referred to, there is no pitting of the casting producedwhen employing such liquid parting powder and such as frequently occurs, due to the generation of carbonic acid (CO2) from any decomposable carbonate con- 49 tained in such dry parting powders.

The term waxy as used in the specification and claims is generic in its significance and relates to substances resembling wax including hard greases, hard fatty acids, resins and waxes.

Various modifications within the scope of the appended claims may be made without departing from the spirit of our invention.

Having thus described our invention, what we claim and desire to obtain by United States Letters 50 Patent is 2-- v 1. A liquid parting for use in metal casting operations, comprising a substantially non-inflammable liquid vehicle consisting of a hydrocarbon derivative having a high evaporation rate and 55 containing [1 to 20%, by weight of a non-sticky, waxy waterproofing substance which is soluble in said vehicle.

2. A liquid parting for use in metal casting operations, comprising a substantially non-inflam- 60 mable liquid vehicle containing at least one member of a groupof liquids consisting of dichlormethane, trichlorethylene, carbon tetrachloride, tetrachlorethane, pentachlorethane, perchlorethylene and dichlorethylene and containing a 65 small percentage, between and 20%, of a.

non-sticky, a waxy waterproofing substance insolution therein.

3. The method of making a sand mold for metal casting purposes, which comprises coating a pattom, corresponding to the metal casting desired, with a. solution containing from to 20%, of a, relatively hard, waxy waterproofing substance in a. volatile, substantially non-inflammable liquid vehicle consisting of a hydrocarbon derivative Furthermore, the parting layer ap- 5 25 tioned in a mold box, riddling molding sand on the sired mold.

4. The method of making a sand mold for metal casting purposes, which comprises spraying a pattern, corresponding to the metal casting desired, with a solution containing from to 20%. of a relatively hard, waxy waterproofing substance in a volatile, substantially non-inflammable liquid vehicle consisting of a hydrocarbon derivative having a high evaporation rate, and then, following the drying of said coating and while said pattern is positioned in a mold box, riddling sand on the pattern and tamping the same inform the desired mold.

5. The method or making a sand mold, which comprises spraying a pattern conforming to the metal casting desired with a dilute solution in a volatile, substantially non-inflammable organic solvent of a non-sticky, waxy waterproofing substance to form a thin coating thereon, then after drying the coating and while said pattern is posipattern and tamping such sand to form one o! the halves of the desired sand'mold.

6. A liquid parting compound, comprising a substantially non-inflammable liquid vehicle, comprising-at'least one member of a group composed of non-inflammable dichlormethane, trichlorethylene, carbon tetrachloride, tetrachlorethane, pentachlorethane. perchlorethylene and dichlorethylene and containing a few percent, and between and 20%, by weight of a nonsticky, waxy waterproofing substance.

I. A liquid parting for use in metal casting operations, comprising a liquid containing a noninflammable halogen derivative of a hydrocarbon,

which has a high evaporation rate and having from 4% to 20% of a non-sticky, waxy waterproofing substance which is soluble in said liquid solution of carbon tetrachloride containing from 2% to 10% oi stearin dissolved therein.

ANDREW Y. GREGORY.

ELDRIDGE E. BEELEY. I 26