US1953844A - Cast type - Google Patents

Description

April 1934- w. s. YERGER m- 1,953,844

CAST TYPE Filed July 15, 1932 r'ceral ge Patented Apr. 3, 1934 UNITED STATES PATENT OFFICE CAST TYPE Pennsylvania Application July 15, 1932, Serial No. 622,734

7 Claims.

more particularly it relates to .cast type made of novel type metal alloys having marked improvements in both casting and printing qualities.

7 One object of our invention is to provide type cast in type casting machines, such as the monotype,1inotype, stereo-type or other machines employed in the printing industries, which type is characterized by properties making it especially 10 desirable and applicable for such use.

Another object of our invention is to provide cast type in which predetermined physical properties, both as to casting ability and wearing quality may be obtained as desired, and in which these factors may be so chosen in relation to. each other as to satisfy the demands of the work for which the type is intended.

A further object of our invention is to provide a cast type in which the casting ability of the molten type metal at the casting temperature is increased whereby more perfect casts are assured with clear reproduction of the details of the mold or mat without undue injury to the casting parts or mold. I

A further object of our invention is to provide a satisfactory cast type which may be obtained at a lower casting temperature, resulting in more rapid freezing, less oxide or dross and the lessening of the corrosive effect of high temperatures on the casting parts of the machine, as well as in the reduction of cost of fuel or electricity required in the melting and. casting of the alloy.

A further object of our invention is to provide a satisfactory cast type made from a type metal by which a marked increase of good and usable casts may be produced in any given period of time, thus materially lowering thecost of production.

Still another object of our invention is to provide a cast type, which may be employed in printing, and appreciably harder and will have a longer life, making more impressions without re-casting than has previously been obtained, and which has a better printing face with clear and more perfect characters and is of greater solidity than the types now employed.

A still further object of our-invention is to provide a method of making cast type of predetermined physical properties-which is characterized by the addition to the usual components of the type of another element in predetermined amounts, depending upon the physical properties desired.

Other objects will be apparent from a consideration of the specification and claims.

()ur invention relates to novel cast type and In the attached drawing, curves showing the properties of two type metal alloys from which cast type falling within the scope of the present invention may be produced are submitted. The curves show the supereutectic and eutectic freezing points and the hardness plotted against the percentage of cadmium'added to an alloy containing 15.7% antimony, 5.4% tin, balance lead (Figure 1), and to an alloy containing 13.5% antimony, 8.0% tin, balance lead (Figure 2).

Cast type contain lead, tin, and antimony alloyed in such amounts as to produce satisfactory type faces when used in commercial type casting equipment. The percentages of these three elements employed in cast type vary widely; for example, the antimony may be present from 10.0% to 28% and the tin from 2.00% to 16%. In all cases, lead makes up the balance with small percentages of other elements, such as arsenic, bismuth, iron, and copper as impurities. The percentage of tin, antimony, and lead in a particular type is determined by'the use for which the type is designed, and type containing given portions of the three elements have become more or less recognized in the trade as suitable for particular purposes.

Since, in the use of type metals in casting equipment, the casts after use are re-melted and re-cast time after time, it is necessary that the type be characterized by satisfactory casting ability with the formation of a minimum amount of oxide or dross while molten in the type casting equipment, since the oxide or dross not only represents a waste of usable metal but also tends to foul the machine and to interfere with the casting. In addition to these qualities, the cast product must be hard enough to withstand the wear of printing. In the manufacture of type, these factors must be taken into consideration and a type metal provided which satisfies these requirements as determined by the particular work for which the cast type is intended. For example, cast type must be suflieiently hard for printing purposes and must be s'umciently fluid at temperatures under 800 F. to fill the mold with out undue injury to the casting parts or mold so that a sharp and clear reproduction of the details of the mold or mat is presented without imperfections. Both the wearing quality and the casting ability of type are made up of various factors.

The cast type is composed of mixed crystals of an antimony and tin component molten at the casting temperature embedded in an eutectic composition of lead, antimony, and tin. Except 110 in the case of a true eutectic mixture, the type metals have two main freezing pointsfirst, the freezing point of the supereutectic structure of the components of the alloy, and second, the freezing point of eutectic ground mass. These freezing points are commonly studied by cooling curves, and the two main breaks show these two points.

The cast type of the present invention is characterized by the presence therein of cadmium in percentages of from .05% to 7.0%. The cast type containing cadmium may be any alloy of tin, antimony, and lead which has the necessary casting and printing qualities, such as the alloys containing the minimum or the maximum limits of antimony and tin hereinabove given. Obviously, the addition of the cadmium will alter the percentage of antimony, tin, and lead employed, but throughout the percentages of these three elements, unless otherwise specified, will be given independently of the impurities and independ ently of the amount of cadmium employed. In addition to the tin, antimony, lead, and cadmium, the type metal will also contain the usual impurities, such as arsenic, bismuth, copper, and iron, and there may also be present small percentages of other elements since it has been determined that their presence does not interfere with the action of the cadmium as described herein.

The presence of the cadmium within the limits of .05% and 7% in the various cast type favorably affects the properties of the type. Even the presence of as low a percentage of cadmium as .05% increases the hardness of the type and improves the casting ability thereof. It also lowers the freezing point of both the eutectic and supereutectic structure. The physical properties obtained in the types containing cadmium vary with the amount of cadmium in the type, as well as with the amounts of tin, antimony, and lead employed. It has been determined that in the case of cast type, two peaks of hardness are obtained' as the percentage of cadmium present in the alloy increases. One of these peaks occurs when the amount of cadmium added is between .25% and .8%, while the second point of maximum hardness occurs when larger proportions of cadmium are added, and is at a definite and specific percentage of cadmium for a specific type. This peak of hardness generally varies between 2% and 7% of added cadmium and is dependent on the richness or amount in per cent. of tin and/or antimony in the specific type. The hardness of the type 'at the second point of maximum hardness is always greater than the hardness of the same type at the first peak. The cadmium, being soluble in the lead base or eutectic, forms solid solutions therewith and hardens the softer ground mass or eutectic component and, therefore, increases the resistance to wear of the type in press runs and increases the resistance to pressure where impressions are taken for stereotype mats. It also advantageously hardens the crystals of tin and antimony compounds embedded in the eutectic ground mass.

The freezing point of the supereutectic structure decreases to a minimum as the cadmium present is increased until the percentage of cadmium reaches a figure which is between the two peaks of hardness. Thereafter, the freezing point of the supereutectic structure increases with increasing cadmium content, becoming in all instances higher than the freezing point of the supereutectic structure of the corresponding alloy to which no cadmium has been added. The freezing point of the eutectic ground mass is also decreased by the addition of cadmium.

In the accompanying curves, the changes of hardness and the changes in the freezing point of the supereutectic and eutectic structure brought about by the addition of varying proportions of cadmium are shown for two typical types. Figure 1 shows these changes in physical properties of a type containing 15.7% antimony, 5.4% tin, balance lead; while Figure 2 shows the changes in a type containing 13.5% antimony, 8% tin, balance lead. In Figure 1, it will be noted that the first peak of hardness occurs when the percentage of cadmium present is approximately .4%; While the second point of maximum hardness occurs when the percentage of cadmium is in the neighborhood of 2.75%. The lowest freezing point of the supereutectic structure of this type is found when the percentage of cadmium present in the type is from 1.5% to 2.25%. In Figure 2, the first peak of maximum hardness is obtained when the percentage of cadmium added is approximately .5%; while the second point of maximum hardness occurs when the percentage of cadmium is approximately 3.25%. The lowest freezing point the supereutectic structure of this type occurs when the cadmium content is in the neighborhood of 2%. The addition of cadmium to other type metals gives corresponding curves, the first point of maximum hardness being found when the percentage of cadmium is present in the neighborhood of 25% to .8%. The second point of maximum hardness, as well as the minimum freezing point of the supereutectic structure, depends upon the type metal employed. It has been determined that as the sum of the amounts of tin and antimony which are employed increases, the more cadmium will be required to give the second point of maximum hardness. Obviously, the specific figures for hardness and for the freezing point of the supereutectic structure will depend upon the particular type metal to which the cadmium is added. The hardness figures given on the curves represent results obtained by the use of the scleroscope It will thus be seen that the percentage of cadmium employed in any given case will depend upon the physical properties desired in the type, although the casting ability of the type is increased by the addition of cadmium within the limits given. The present invention makes it possible to employ the cadmium in predetermined amounts, depending upon the demands of the work for which the type is intended. It is possible to select the hardness and casting ability desired in the type and to obtain the desired properties in the finished product bythe addition of predetermined amounts of cadmium thereto. In some instances, it will be desirable to employ the cadmium in amounts sufiicient to produce the maximum hardness of the cast type even though the freezing point of the supereutectic structure is not materially below that of the freezing point of the supereutectic structure of the type containing no cadmium. In other instances, it will be desirable to balance these factors and to sacrifice a certain amount of hardness in order that a type may be produced in which the freezing point of the supereutectic structure thereof is materially reduced. Furthermore, in all cases the freezing point of the supereutectic structure is lowered at the first point of maximum hardness, that is, when the cadmium content is in the neighborhood of 25% to .8%. In these cases,

no balancing between the amount of hardness desired and the lowering of the freezing point of the supereutectic structure is necessary.

Since the first peak of hardness occurs in all cast type when the proportion of cadmium of from 25% to .8% is added, no further examples are necessary as to this peak. It is to be understood, however, that the peak varies with the type to which the cadmium is added, but due to the difficulties encountered in the determination of these small percentages of cadmium, it is sufficient merely to give the limits. Referring to the second point of maximum hardness, the following table will give the amount of cadmium to be added to obtain the maximum hardness, in certain additional types, although it will be understood that these are only a few of the types to which the invention is applicable. The table also shows the freezing point of the supereutectic structure and the solidification temperature (freezing point of the eutectic ground mass) obtained with the types at the point of maximum hardness. In order that a comparison may be made, figures are included showing the hardness and freezing points of the corresponding types to which no cadmium has been added.

Solidifi Tin Anti- Oad Bardm s cation mouy mium ness mm 2 temperature ture Degrees F. Degrees F. 14 13 467 460 14 1 2. 00 16% 464 448 13% 13 488 45s 13% 3. 00 17% 493 449 the casting ability of the type when molten. The

casts obtained are sharp and free from defects including cold shots. This increase in casting ability results in clear reproduction of the details of the mold or mat, with a great reduction in the number of imperfections, and the metal completely fills the mold without undue injury to the casting parts or mold. The casts resulting from the present invention are more perfect and are of greater solidity, that is to say, are of less porosity than the cast type in which cadmium is not employed. The presence of the cadmium also lowers the casting temperature required for successful operation, which is of marked advantage since the corrosive effect of high temperatures on the casting parts of the machine are reduced to a minimum and the cost of the fuel or electrical heat required for operation is decreased. The lowering of the casting temperature required for successful operation also reduces the amount of oxide or dross formed during use of the type of this composition when molten.

The addition of cadmium to the type in addition to increasing the casting ability also causes more rapid freezing of the casts. This property increases the speed of operation of the casting machine, thereby lowering the cost of production since there is a markw increase in the number of good andusable casts produced in any given period of time. For example, in a mono-type machine, if the best operating speed for a specific size and type of v character is eighty casts per minute with a given type, the speed may be increased to one hundred twenty casts per minute by the addition of cadmium as disclosed herein.

The cast types of the present inventionalso have improved wearing qualities. The casts present a better printing face, with clear and more perfect characters and have a longer life, making more impressions without recasting than the corresponding types in which the cadmium is omit-- ted. For example, a cast containing 13.5% antimony, 8.0% tin, balance lead, with traces of the usual impurities of commercial metals, is capable of printing without undue wear approximately 40,000 impressions with favorable press conditions. type increases the wearing quality of the cast, so that the number of impressions is increased to approximately 60,000; while the addition of 3% of cadmium increases the number of impressions that are possible to more than 100,000.

In making the cast type of the present invention, the cadmium may be incorporated in any suitable manner. For practical purposes, it has been found satisfactory to prepare a molten type containing the desired amounts of antimony, tin, and lead, and thereafter to add cadmium thereto in the desired predetermined percentage. The temperature required depends to some extent upon the percentages of the various elements present, but in general varies from 650 F. to 750 F.

, Considerable modification is possible in the percentages of antimony, tin, and lead employed in the type with the cadmium, as well as in the specific amount of cadmium used within the limits given, without departing from the essential features of the present invention.

We claim:

1. A cast type of improved properites comprising mixed crystals of an antimony and tin component molten at the casting temperature, embedded in an eutectic composition of lead, tin and antimony, the antimony being between 10% and 28%, the tin being between 2% and 16%, the balance being substantially all lead, containing cadmium added thereto in percentages from 05% to 7%.

2. A cast type of improved properties comprising mixed crystals of an antimony and tin component molten at the casting temperature, embedded in an eutectic composition of lead, tin and antimony, the antimony being between 10% and 28%, the tin being between 2% and 16%, the balance being substantially all lead, containing cadmium added thereto in percentages from 05% to 1.5%. p

3. A cast type of improved properties comprising mixed crystals of an antimony and. tin com ponent molten at the casting temperature, embedded in an eutectic composition of lead, tin and antimony, the antimony being between 10% and 28%, the tin being between 2% and 16%, the balance being substantially all lead, containing cadmium added thereto in percentages from 2% to 7%.

4. A cast type of improved casting qualities, lowered casting temperature, and increased hardness, comprising mixed crystals of an antimony and tin component, molten at the casting temperature, embedded in an eutectic composition of lead, antimony and tin, the antimony being be- The addition of .4% cadmium to this tween 10% and 28%, the tin being between 2% and 16%, the balance being substantially all lead, containing cadmium added thereto in predetermined percentages from .05% to 7%, the improvement in said physical properties being controlled by the percentage of cadmium added.

5. A cast type of improved casting qualities, lowered casting temperature, and increased hardness, comprising mixed crystals of an antimony and tin component, molten at the casting temperature, embedded in an eutectic composition of lead, tin and antimony, the antimony being between 10% and 28%, the tin being between 2% and 16%, the balance being substantially all lead, containing cadmium added thereto in predetermined percentages from .05% to 1.5%, the improvement in said physical properties being controlled by the percentage of cadmium added.

6. A cast type of improved casting qualities, lowered casting temperature, and increased hardness, comprising mixed crystals of an antimony and tin component, molten at the casting temperature, embedded in an eutectic composition of lead, tin and antimony, the antimony being between 10% and 28%, the tin being between 2% and 16%, the balance being substantially all lead, containing cadmium added thereto in percentages from 2% to 7%, the improvement in said physical properties being controlled by the percentage of cadmium added.

"I. A cast type of improved casting qualities, lowered casting temperature, and increased hardness, comprising mixed crystals of an antimony DQSOLAEMER 1,953,844.Wils0n S. Y erger and Lewis S. Somers, Philadelphia, Pa.

Patent dated April 3, 1934.

CAST TYPE. Disclaimer filed November 29, 1937, by the assignee, Imperial Type Metal Company.

Here[bby enters this disclaimer to claims 1, 2, 4, 5, and 7 in said patent. fiicwl Gazette December 28, 1.937.]

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