US404238A - Molding material - Google Patents

Description

UNITED STATES PATENT OFFICE.

CHARLES H. \VILDER, OF N ATICK, MASSACHUSETTS.

MOLDING MATERIAL.

SPECIFICATION forming part of Letters Patent No. 404,238, dated May 28, 1889. Application filed March 1, 1889. Serial No, 801,697. (No specimens.)

To all whom it may concern.-

Be it known that I, CHARLES H. WILDER, of Natick, in the county of Middlesex and State of Massachusetts, a citizen of the United States, have invented a certain new and Improved Molding Material, of which the following is a specification.

My invention relates to an improvement in the material or substance to be used for the formation of a mold from which to cast articles of metal. I

The object of my invention is to producea composition or material for this purpose such that it will not be fused or fluxed by contact with the molten metal, but will at all times have and-preserve a smooth and indestructible molding-face, so that more perfect castings can be obtained from it than has heretofore been possible by the use of the molding-sand or other materials commonly employed for the purpose.

My improved mold material consists of a mixture of pulverized coke and pulverized graphite, or, as it is commercially known, plumbago.

In preparing this mixture I grind each of the substances to as fine a powder as is readily practicable, the graphite, as is well known, being capable of a considerably finer reduction than the coke. After the two substances have been thus ground I unite or incorporate them with a suitable cokable binder, such as pitch. This binder I make plastic by heat, and then mix it and the pulverized coke and graphite together. The mass thus formed I then inclose within a suitable case and heat it in a furnace to a sufficient temperature and for a suflicient time to coke the binder. When this has been done and the mass has cooled, I pulverize it to the required degree of fineness, substantially that of molding-sand. The powder or sand thus obtained can be used like ordinary molding-sand, but with greatly-improved results. The function of the coke in the mixture thus formed is that which comes from its refractory and infusible character. The function of the graphite is also that which comes from its refractory character and, as is well known, through its capacity, by reason of its relatively'greater fineness of grain, to fill up and permeate the interstices that occur among the grains of coke. The function of the binder is to bring about the union in a homogeneous compound of equally refractory and infusible nature throughout of the coke and graphite, which without the use of such a binder could not be practically united.

My improved mixture possesses a more compact texture or grain, and consequently a greater capacity for exactly preserving and reproducing the form of the article to be cast, than would be possible if powdered coke alone were employed. Inasmuch, however, as the graphite is more costly than the coke, no more of it should in practice be introduced into the mixture than is necessary to give to it the improved qualities above set forth.

I have found in practice that good results are obtained by using graphite in the proportion of about one-fourth or one-fifth of the Whole mass of the mixture; but the proportion will be found to vary according to the class of Work for the production of which the molding material is to be used.

Enough of the binding material should be employed to thoroughly unite the mass. I have found in practice that it is desirable to employ the binder in such proportion as to giveto the whole mass before coking substantially the consistency of mortar for bricklaying.

The mixture of coke, graphite, and binder above described may be used in the same manner as common molding-sand is now employed, and is intended to serve as a substitute therefor.

I claim As an improved molding material, a composition of matter comprising coke, graphite, and a coked binder in a loose granular form, as set forth.

In testimony whereof I have hereunto subscribed my name this 25th day of February, A. D. 1889.

CHARLES H. WILDER.

\Vitnesses:

JOHN H. TAYLOR, WILLIAM B. Ron.