General Electric Co. v. Willey's Carbide Tool Co.

• Decision Date: 19 July 1940
• Docket Number: Civil No. 432.,Equity No. 7392
• Citation: 33 F. Supp. 969
• Parties: GENERAL ELECTRIC CO. et al. v. WILLEY'S CARBIDE TOOL CO. et al.
• Court: U.S. District Court — Western District of Michigan

33 F. Supp. 969

GENERAL ELECTRIC CO. et al. v. WILLEY'S CARBIDE TOOL CO. et al.

Equity No. 7392; Civil No. 432.

District Court, E. D. Michigan, S. D.

July 11, 1940.

Supplemental Opinion July 19, 1940.

Bulkley, Ledyard, Dickinson & Wright, of Detroit, Mich. (by Glenn D. Curtis, of Detroit, Mich.,) and Watson, Bristol, Johnson & Leavenworth, of New York City (by Lawrence Bristol and Charles P. Bauer, both of New York City), for plaintiffs.

Barnes, Kisselle, Laughlin & Raisch, of Detroit, Mich. (by Arthur Raisch, of Detroit, Mich.), for defendants.

TUTTLE, District Judge.

This is a suit for patent infringement. The patents claimed to be infringed, arranged in order of filing dates, are as follows:

Karl Schroter, Reissue No. 17,624, reissued March 18, 1930, original No. 1,549,615, issued August 11, 1925, application October 31, 1923;

Karl Schroter, No. 1,721,416, issued July 16, 1929, application April 26, 1926;

Samuel L. Hoyt, No. 1,843,768, issued February 2, 1932, application April 6, 1927;

Benno Strauss, No. 1,812,811, issued June 30, 1931, application April 14, 1927;

Emery G. Gilson, No. 1,756,857, issued April 29, 1930, application April 28, 1927; George F. Taylor, No. 1,996,598, issued April 2, 1935, application April 23, 1929.

The first five of these patents relate to the same alloy and/or methods of manufacturing it, which alloy is used principally for wire drawing dies and as a tip for metal cutting tools. Of the patents in suit, the alleged invention covered by the Schroter reissue patent No. 17,624 was first in time. Schroter proposed to mix pulverized tungstic carbide containing from 3 to 10% carbon with not more than 10% of a finely divided metal from the iron group (iron, cobalt and nickel), press these mixed powders while cold into a body, and then heat the pressed body to sinter the same. Schroter suggested suitable sintering temperatures between 1500 and 1600° C. These sintering temperatures are above the melting point of the iron group metal and below the melting point of the tungstic carbide. Thus, the iron group metal melts, takes some of the tungstic carbide into solution and consolidates, binds, or cements the tungstic carbide particles together. This Schroter reissue patent does not disclose that this alloy is suitable for cutting tools or for wire drawing dies. As to the usefulness of the alloy claimed in the Schroter reissue, nothing is stated except that the "alloy is suitable for making working implements of various sorts and which is particularly suitable for making hones".

Having limited himself in this Schroter reissue patent to an alloy or sintered composition containing 10% or less of iron group metal, Schroter's second patent, No. 1,721,416, covers exactly the same alloy as the Schroter reissue except that the iron group metal content covers the field left open by the Schroter reissue, namely, the entire range above 10% of the composition.

The Hoyt patent No. 1,843,768 came next in point of time. Hoyt has claims for both product and process. It covers the composition of both the Schroter patents, but instead of cold pressing the powders into a body and then sintering the body, Hoyt presses the mixture of tungsten carbide and iron group metal powders and simultaneously heats the mixture to its sintering temperature.

Strauss No. 1,812,811 covers the same method for making the alloys of both the Schroter patents, but adds the step of mixing the tungsten carbide and iron group metal powders by ball milling for fifty hours or more.

Gilson No. 1,756,857 is for a process, and differs from Hoyt in but one respect, namely: Gilson mixes powdered tungsten, powdered carbon, and a powdered metal from the iron group, and then simultaneously presses and heats the three powders to sintering temperature, whereas Hoyt uses the two powder method, namely; a mixture of powdered tungsten carbide and a powdered iron group metal which are simultaneously pressed and heated to sintering temperature. Gilson's product or alloy is exactly the same as that of Hoyt and the two Schroter patents.

Taylor No. 1,996,598 is for a product and process. It relates to a diamond impregnated abrading tool. Taylor takes the composition of the two Schroter patents, namely; tungsten carbide powder and an iron group metal powder, mixes these with diamond powder and then simultaneously presses and heats the mixture to its sintering temperature according to the Hoyt process. The resulting product consists of a legion of fine tungsten carbide particles and diamond particles which are bound or cemented together by the iron group metal.

For certain purposes, cemented tungsten carbide is the best cutting material known today. Tungsten carbide is a chemical combination which exists in two forms: WC, wherein one atom of tungsten has chemically reacted with one atom of carbon to form a molecule, and W2C, wherein two atoms of tungsten have chemically reacted with one atom of carbon to form a molecule. Both WC and W2C are known as tungsten carbide. In the chemical compound WC the carbon forms 6.12% by weight of the tungsten carbide, whereas in W2C the carbon forms 3.15% by weight of the tungsten carbide. One of the common and successful ways of making tungsten carbide is by heating tungsten powder and carbon powder in a furnace having a hydrogen atmosphere at a temperature of about 1550° C. If more than 6.12% of carbon is added to the mixture of tungsten and carbon powder, then the carburized tungsten will contain WC plus free carbon. If the mixture of tungsten powder and carbon powder contains less than 3.15% of carbon, then the final product will contain W2C plus some free tungsten. Schroter's preferred carburized tungsten contains 7% carbon, that is, WC plus .88% free carbon. Schroter suggests a carbon range in his carburized tungsten of from 3 to 10%. Thus, at the upper end of the carbon range one would obtain tungsten carbide plus approximately 4% free carbon. At the lower end of the range one would obtain W2C plus a small amount of free tungsten.

The best cutting and abrading material for a cemented Tungsten carbide tool is WC, that is, tungsten carbide having a carbon content of 6.12%. W2C is not as desirable as WC because it is not as hard as WC. To obtain optimum results neither free carbon nor free tungsten is desirable. The sintered composition of tungsten carbide and iron group metal is commonly referred to as "cemented tungsten carbide", that is, the iron group metal cements or binds together the tungsten carbide particles. The plaintiffs use cobalt (one of the iron group) as their binder metal, whereas the defendants use nickel (another one of the iron group) as their binder metal.

Tungsten carbide is a hard, brittle substance. It is not as hard as diamond but compares favorably in hardness with the diamond and is, of course, considerably cheaper. The three members of the iron group (iron, nickel and cobalt) are tough, relatively soft metals. Thus, in the finished composition, tungsten carbide gives the composition hardness and the binder metal of the iron group gives the composition toughness. Both hardness and toughness are essential in the metal cutting tools. Cemented tungsten carbide has about half the toughness (transverse rupture strength) of high speed tool steel, but is considerably harder and is considerably superior as a cutting material. Due to its weakness, however, the cemented tungsten carbide is merely used as the cutting tip of a cutting tool. The tip is copper brazed on a steel shank. The cemented tungsten carbide tip is set into the steel shank so that it is supported on its bottom and two of its sides by the steel shank which decreases breakage of the tip, which otherwise would result from the weakness of the material. When used as a wire drawing die, only the nib (the wear surface immediately surrounding the opening) of the die is made from cemented tungsten carbide, the nib being surrounded by a steel casing which supports and reinforces the cemented tungsten carbide nib.

In making commercially successful cemented tungsten carbide, numerous detail steps not disclosed or claimed by any of the patents in suit are necessarily carefully followed, each of which is vitally important in obtaining the superior cutting tool material as we know it today. These details are too numerous to set forth in entirety but a few will be mentioned. To obtain commercially good tools of different hardness and toughness, it is essential to use WC of different degrees of fineness and to vary the percentage of binder metal. The hardness of the tool is inversely proportional to the particle size of the tungsten carbide. To obtain a tool having a given toughness, the amount of binder metal required increases with decreasing grain size. In reducing tungstic oxide (the form in which tungsten usually occurs in nature) to obtain tungsten powder, it is important that the particle size of the tungsten powder be exceedingly fine. Such exceedingly fine tungsten powder can be obtained in the reduction of tungstic oxide to powdered tungsten only by carefully following a highly refined technique.

Similarly, in carburizing the tungsten to form tungsten carbide (WC), exact proportions of tungsten powder and carbon powder must be mixed and introduced into the furnace in order to obtain the tungsten carbide (WC 6.12% carbon). In forming tungsten carbide, time and temperature are important as well as the purity of the tungsten powder and carbon powder (lampblack) used. The tungsten powder as well as the tungsten carbide powder, to prevent oxidation and other harmful changes, should preferably be stored under conditions wherein the temperature and relative humidity of the atmosphere are carefully controlled. The mixing of the tungsten carbide powder and the binder metal must be carefully controlled to avoid introduction of impurities into the mixture. In cold pressing the mixed tungsten carbide and iron group metal...