Diamonds as Tools Speed Up Victory RUTH C. LESLIE Bureau of Foreign and Domestic Commerce, Washington, D. C. I T 'IS said that every important weapon used by our armed forces requires the diamond in its manufacture. Thus, under the exigencies of war, the diamond has become an industrial necessity. And there is no reason t o believe that this development will not continue. The change which has come about will. i t is felt, furnish a sounder foundation for diamond mining than the industry has heretofore enjoyed except in the production of gem stones. In the future the industrial diamond will be regarded as a of anv modern eneineerine. normal nart of the eoui~ment . . -. industrial, or mining enttrprire. A s ortc unmi.itakahle evidence of thiq, the indust631 diamond has been stripped of its mantle of preciousness and is now sold in large quantities by the kilngram instead of by the carat. The importance of the diamond in industry will best be seen in its relation to the woduct i t helps t o make. But, first, a word about the diamGd itself. I t ispure carbon in the natural crystalline form and is the hardest natural substance known. It is a nonconductor of electricity and will burn in oxygen if ignited a t sufficiently high temperature. The diamond is usually found in the form of smaU stones, but only the most perfect specimens, colorless or tinted blue or yellow, are suitable for use as gem stones. The bulk of diamond production consists of stones that are dark, opaque, translucent, or flawed. These are the industrial diamonds upon which modern industry is so dependent. They were formerly merely a byproduct of gem-stone miningfortunate circumstance in itself for had i t not been for the large stocks of "waste product" built up aver the centuries of mining diamonds for luxury uses, the demands of war could not have been met. There are three types of industrial diamonds: (1) Bort, a trade name for those stones too badly flawed or off-color to be used in jewelry; (2) carbonado or black diamond, a closely knit aggregate of excessively small diamond crystals; and (3) ballas, a globular mass of diamond crystals radiating from a common center. Each tvoe is distinmished hv certain characteristics bort, for hardness and comparative cheapness; carbonado, for extreme touglmcss; and ballas, for harrlness and toughnew. I\'either earhotvado nor ballas exhibits the characteristic cleavage of hort. The major portion of the normal year's production of diamond mining is made up of bort, which is a by-product of diamond mining in all producing countries. Carhonado comes from Bahia, Brazil, while ballas comes from Brazil. as well as certain of the other South American countries. World production of all diamonds (gem and industrial) in 1943 was only 8,191,360 carats, compared with 13,012,525 carats in 1940. Approximately four-fifths were industrial diamonds. Consumption of industrial diamonds, however, increased by leaps and bounds during this period t o a t least double production. As stated previously, i t is fortunate that stocks accumulated through the years have been adequate. Based an 1944 consumption data, industrial applications of diamonds are divided as follows: Use in grinding wheels, 87 per cent; as brilling material. 7 per cent; in diamond-set tools, 5 per cent; stones for wire-drawing dies, 0.5 per cent; and miscellaneous uses, 0.5 per cent. Prewar consumption of industrial diamonds in the United States was about 1,250.000 carats annually. use increasing t o some 10,000,000 carats in 1943. United States consumption is met by importation. Imports during the 5-year period 193943 were as follows: ~~
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1939 1940 1941
m a
1943
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8,568,730 3.809.071 6,882,248 11.203.704 12,172,679
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$9,725,683 11.026.563 14.908.809 22,057,577 21.938.368
$2.73 2.89 2.17 1.97 1.80
Care samples in rock drilling are taken by the use of diamondset core drills. No other cutting medium is hard enough t o penetrate effectively the thousands of feet necessary in this operation. At one time the only means of sinking boreholes in hard rock was by use of percussion and hammer drills. Bare dust thus accumulated gave very poor indication of the composition and sequence of the strata. It was not until the middle of the 19th century that engineers took advantage of the intense hardness of the diamond for drilling operations. A boring crown set with diamonds and fixed a t the end of a system of hollow rods is brought t o bear on the rock with even pressure and revolved. The core thus obtained gives a very precise indication of the character of the strata, as *ell as their sequence and dip, besides affording the most excellent material for analysis. Formerly carbonado and ballas were used far this operation, but they are now largely superseded by bort, except for the very hard formations. Diamond core drills are used for driving boreholes t o all depths, from 15 feet t o several thousand. They are made in a large range of diameters, from 36 millimeters for ore prospecting up to 50 centimeters for large borings in coal mines and for oil wells. Diamond drills are also used in mining for blasthole work and like operations. Important uses are for making emergency boring~ where a sudden inrush of water or gas is expected, for rapidly establishine ventilation. and for extinction of undermound 6res i l l mines. The diamond drill is of great value in locating suitahle foundations for hndges and other luge structures which must rest an rock bottom. Diamonds set in drill hits are extensively used in mining for base metals. Recent developments in high-speed light drills make the diamond an important factor in all types of drilling. includine such widely divercent activities as the buildine.of dams and thedrilling of oil wellsEvery concern working with metal finds the diamond iudir pensable in normal times as well as in times of war, especially when speed and precision are essential. Diamond-set tools are used in cutting and machining metals and the turning of rough and fibrous materials in lathe work. The most general use of the diamond-set t a d in industry is for truing and shaping abrasive wheels. They are essential in the truing of wheels used t o grind gun bores, pistons, valves, and crankshafts in scout cars, tanks, airplanes, submarines, and so on. There is an ever-increasing demand for shaped diamond tools for turning, threading, and truing of various rolls in paper mills and for accurately and rapidly working hard, fibrous substances. such as ebonite and wlcsnite. The great advantage is that they will produce highly accurate work for long periods without regrinding. Diamond-set saws, drills, and pointed instruments will cut stone, glass, and porcelain. Diamond saws are made in various pattern-ircular (up t o 10 feet in diameter); reciprocating (up t o 25 feet in length); hand saws, and slitting saws. The cutting diamonds are mounted in detachable steel sockets inserted a t regular intervals along the saw. Incorporated in saws, fragmented diamond bort is used t o manufacture quartz crystal oscillators for radio and radar. A new type of diamand-set dressing tool for thread grindmg wheels has been announced which is said t o have increased production 500 per cent and reduced production cost as much as 75 per cent. Diamond grinding wheels have made possible the un~recedentedgrowth in cemented tungsten carbide twls, since the diamond is the only available material hard enough t o grind tungsten carbide. Diamond grinding wheels are used also in the manufacture of shells and cartridge casings, in optical grinding. such as generating the curves on optical lenses, and for ceramics, such as spark plugs. The diamond is used by the dental surgeon in drilling teeth.
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DIAMONDS AS TOOLS SPEED UP VICTORY (Continued from page 513) I t is also employed in fashioning the delicate hearings in watches end sensitive scales. The engineer's drilling tool is tipped with diamonds set in silver. Many etching and engraving tools are diamond-tipped. Diamonds are also used in the atomizers of oil-burning furnaces, and in reproducing points for making master phonograph records. Diamonds are used in machining cylinders for printing cards; in regrwving burrstones in milling mustard; in grinding superhard alloys of aluminum, nickel, and cobalt; in preparing eneravine tools for -elass:. .for drilline and makine - nozzles for sand "~~ Ihsting; and to slit irirl~um-pointednibs of fountain yens 0.0r.7 of an inch thick. There rs a sr,eci:ili?ed tool employing the dia~nondtocut cores from concrete wads to as;crtain the amount of wear they have undergone. Diamond powder-itself a by-product of other diamond u s e s is employed for cutting diamonds and for various mechanical purposes. Graded diamond powder makes possible the manufacture of lenses for hombsights, navigation instruments, cameras. and binoculars, as well as jewel bearings used in precision instruments. Dismond dust is used extensively in diamond laps for operations where extreme precision is t o he attained. These laps are of soft steel charged with the diamond dust. Diamond points are elongated thin stones obtained in the natural state and cleaved, sawn, or polished. They are used for drilling glass, for graduating measuring and astronomical instruments, and for graving tools of different kinds. Glaziers' diamonds are very small b o r t a s many as 80 t o the earst-used in cutting glass, and are obtainable in a wide range of qualities. The splints which accumulate when diamonds are cleaved are used mainly by optical and glass works. A diamond die is a pierced diamond. All wire is drawn through a die. There is no adequate substitute for the diamond die in the production of superfine wires, those 0.0015 of an inch and smaller in diameter, which are required for radio and radar eouioment. so essential in ooeratine olanes. tanks.. shins. . . ieeos. ... guns, and other war mat4riel. and for many other types of scientific instruments. Constancy of diameter is absolutely essential for purposes of ~
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measuring electrical conductivity, strength constants, and other characteristics of instruments required by the armed forces. I t is this constancy of diameter which can be supplied only by diamond dies. Great quantities of wire may be drawn through these dies without variation of diameter. The United States formerly imported all of its finest-sized diamond dies and the major portion of its larger-sized dies. In 1940, when these dies were no longer obtainable from abroad in sufficient quantities t o meet the stepped-up demand, this country was faced with the necessity of creating an entire new industry. For althoueh the diamond-die manufacturers of the United States sere prepared to meet the demand for dies of larger dimvniions there w a i not a single prrwlucer of the smaller die, in this country. However, American ingennity, with the aid of a few skilled workers transplanted from Europe and the use of mass-production methods, has evolved in the few short war years a die-making industry fully capable of filling all our requirements for this vitally strategic product. Prior to the war, fram 115 t o 170 man-hours were required t o make a die of the smaller sizes. United States die makers speeded up the process so that by early 1944 the over-all average time was reduced t o about 25 man-hours per die. The electric drilling method developed a t the Bureau of Standards requires fram 4 t o 4'/* man-hours per die, and greatly reduces the production cast per die. An even greater reduction in time and cost may he possible when this development has became completely commercialized. Some idea of what thcse advancements in the art of diamonddie making hare meant in the war cRort may be gained by a glimpse at praluction figures of both die and wire manufacturers during the war period. Domestic production of dies of the strategic sizeP0.0015 of an inch and smaller-in 1943 appro xi mat el^ doubled t h a t of 1942. and a t all times during the war all requirements for fine wire have been met. The amount of superfme wire drawn in 1944 exceeded all previous levels, being 13 per cent above the 1943 total and 85 per cent above 1942.-Reprinted from Domestic Commercc (August. 1945). ~
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