MATERIALS 3035 They are then rinsed with water and dried with alcohol. Very thin layers of iron sulphide are deposited on the different constituents in different thicknesses, and this gives them dif- ferent colors. Austenite remains a pale brown; martensite is given a pale blue and deep blue and brown color; troostite is made very dark; sorbite is uncolored; cementite exhibits a brilliant white; and ferrite is made dark brown. When the etching has proceeded to the desired extent, the specimen is at once washed thoroughly in order to remove all trace of the etching reagent. Usually it is simply rinsed with water, but frequently the washing is done with absolute alcohol, while ether and chloroform are also sometimes used. The apparatus used for examining the etched surfaces of metals is composed of a micro- scope and camera combined with an arc lamp or other means of illumination. Microscopic Study of Steel: Steel, in particular, shows many changes of structure due to the mechanical and thermal treatment, so that the microscope has become a very valuable instrument with which to inspect steel. To one who understands what the different forma- tions of crystalline structure denote, the magnified surface reveals the temperature at which the steel was hardened, or at which it was drawn, and the depth to which the hardness penetrated. It also shows whether the steel was annealed or casehardened, as well as the depth to which the carbon penetrated. The carbon content can be closely judged, when the steel is annealed, and also how much of it is in the graphitic state in the high carbon steels. The quantity of special elements that is added to steel, such as nickel, chromium, tungsten, etc., can also be estimated, when the alloy to be examined has been put through its pre- scribed heat-treatment. Likewise, the impurities that may be present are clearly seen, regardless of whether they are of solid or gaseous origin. Micarta.—Micarta is a non-metallic laminated product of specially treated woven fabric. By means of the various processes through which it is passed, it becomes a homogenous structure with physical properties which make it especially adapted for use as gears and pinions. Micarta can be supplied either in plate form or cut into blanks. It may also be molded into rings or on metal hubs for applications such as timing gears, where quantity production is attained. Micarta may be machined in the ordinary manner with standard tools and equipment. Micarta gears do not require shrouds or end plates except where it is desired to provide additional strength for keyway support or to protect the keyway and bore against rough usage in mounting drive fits and the like. When end plates for hub support are employed they should extend only to the root of the tooth or slightly less. Properties: The physical and mechanical properties of Micarta are as follows: weight per cubic inch, 0.05 pound; specific gravity, 1.4; oil absorption, practically none; shrinkage, swelling or warping, practically none up to 100 degrees C.; coefficient of expansion per inch per degree Centigrade, 0.00002 inch in the direction parallel to the laminations (edge- wise), 0.00009 inch in the direction perpendicular to the laminations (flat wise) ; tensile strength, edgewise, 10,000 pounds per square inch; compressive strength, flat wise, 40,000 pounds per square inch; compressive strength, edgewise, 20,000 pounds per square inch; bending strength, flatwise, 22,000 pounds per square inch; bending strength, edge- wise, 20,000 pounds per square inch. Monel.—This general purpose alloy is corrosion-resistant, strong, tough and has a sil- very-white color. It is used for making abrasion- and heat-resistant valves and pump parts, propeller shafts, laundry machines, chemical processing equipment, etc. Approximate Composition: Nickel, 67; copper, 30; iron, 1.4; silicon, 0.1; manganese, 1; carbon, 0.15; and sulphur 0.01. Average Physical Properties: Wrought Monel in the annealed, hot-rolled, cold-drawn, and hard temper cold-rolled conditions exhibits yield strengths (0.2 per cent offset) of 35,000, 50,000, 80,000, and 100,000 pounds per square inch, respectively; tensile strengths of 75,000, 90,000, 100,000, and 110,000 pounds per square inch, respectively; Machinery's Handbook 27th Edition Copyright 2004, Industrial Press, Inc., New York, NY 3036 MATERIALS elongations in 2 inches of 40, 35, 25, and 5 per cent, respectively; and Brinell hardnesses of 125, 150, 190, and 240, respectively. “R” Monel.—This free-cutting, corrosion resistant alloy is used for automatic screw machine products such as bolts, screws and precision parts. Approximate Composition: Nickel, 67; copper, 30; iron, 1.4; silicon, 0.05; manganese, 1; carbon, 0.15; and sulphur, 0.035. Average Physical Properties: In the hot-rolled and cold-drawn conditions this alloy exhibits yield strengths (0.2 per cent offset) of 45,000 and 75,000 pounds per square inch, respectively; tensile strengths of 85,000 and 90,000 pounds per square inch, respectively; elongations in 2 inches of 35, and 25 per cent, respectively; and Brinell hardnesses of 145 and 180, respectively. “K” Monel.—This strong and hard alloy, comparable to heat-treated alloy steel, is age- hardenable, non-magnetic and has low-sparking properties. It is used for corrosive appli- cations where the material is to be machined or formed, then age hardened. Pump and valve parts, scrapers, and instrument parts are made from this alloy. Approximate Composition: Nickel, 66; copper, 29; iron, 0.9; aluminum, 2.75; silicon, 0.5; manganese, 0.75; carbon, 0.15; and sulphur, 0.005. Average Physical Properties: In the hot-rolled, hot-rolled and age-hardened, cold- drawn, and cold-drawn and age-hardened conditions the alloy exhibits yield strengths (0.2 per cent offset) of 45,000, 110,000, 85,000, and 115,000 pounds per square inch, respec- tively; tensile strengths of 100,000, 150,000, 115,000, and 155,000 pounds per square inch, respectively; elongations in 2 inches of 40, 25, 25, and 20 per cent, respectively; and Brinell hardnesses of 160, 280, 210, and 290, respectively. “KR” Monel.—This strong, hard, age-hardenable and non-magnetic alloy is more readily machinable than “K” Monel. It is used for making valve stems, small parts for pumps, and screw machine products requiring an age-hardening material that is corrosion-resistant. Approximate Composition: Nickel, 66; copper, 29; iron, 0.9; aluminum, 2.75; silicon, 0.5; manganese, 0.75; carbon, 0.28; and sulphur, 0.005. Average Physical Properties: Essentially the same as “K” Monel. “S” Monel.—This extra hard casting alloy is non-galling, corrosion-resisting, non-mag- netic, age-hardenable and has low-sparking properties. It is used for gall-resistant pump and valve parts which have to withstand high temperatures, corrosive chemicals and severe abrasion. Approximate Composition: Nickel, 63; copper, 30; iron, 2; silicon, 4; manganese, 0.75; carbon, 0.1; and sulphur, 0.015. Average Physical Properties: In the annealed sand-cast, as-cast sand-cast, and age-hard- ened sand-cast conditions it exhibits yield strengths (0.2 per cent offset) of 70,000, 100,000, and 100,000 pounds per square inch, respectively; tensile strengths of 90,000, 130,000, and 130,000 pounds per square inch, respectively; elongations in 2 inches of and 3, 2, and 2 per cent, respectively; and Brinell hardnesses of 275, 320, and 350, respectively. “H” Monel.—An extra hard casting alloy with good ductility, intermediate strength and hardness that is used for pumps, impellers and steam nozzles. Approximate Composition: Nickel, 63; copper, 31; iron, 2; silicon, 3; manganese, 0.75; carbon, 0.1; and sulphur, 0.015. Average Physical Properties: In the as-cast sand-cast condition this alloy exhibits a yield strength (0.2 per cent offset) of 60,000 pounds per square inch, a tensile strength of 100,000 pounds per square inch, an elongation in 2 inches of 15 per cent and a Brinell hard- ness of 210. Nichrome.—“Nichrome” is the trade name of an alloy composed of nickel and chromium, which is practically non-corrosive and far superior to nickel in its ability to withstand high Machinery's Handbook 27th Edition Copyright 2004, Industrial Press, Inc., New York, NY MATERIALS 3037 temperatures. Its melting point is about 1550 degrees C. (about 2800 degrees F.). Nichrome shows a remarkable resistance to sulphuric and lactic acids. In general, nichrome is adapted for annealing and carburizing boxes, heating retorts of various kinds, conveyor chains subjected to high temperatures, valves and valve seats of internal com- bustion engines, molds, plungers and conveyors for use in the working of glass, wire bas- kets or receptacles of other form that must resist the action of acids, etc. Nichrome may be used as a substitute for other materials, especially where there is difficulty from oxidation, pitting of surfaces, corrosion, change of form, or lack of strength at high temperatures. It can be used in electrically-heated appliances and resistance elements. Large plates of this alloy are used by some manufacturers for containers and furnace parts, and when perfo- rated, as screens for use in chemical sifting and ore roasting apparatus, for services where temperatures between 1700 degrees F. and 2200 degrees F. are encountered. Strength of Nichrome: The strength of a nichrome casting, when cold, varies from 45,000 to 50,000 pounds per square inch. The ultimate strength at 200 degrees F. is 94,000 pounds per square inch; at 400 degrees F., 91,000 pounds per square inch; at 600 degrees F., 59,000 pounds per square inch; and at 800 degrees F., 32,000 pounds per square inch. At a temperature of 1800 degrees F., nichrome has a tensile strength of about 30,000 pounds per square inch, and it is tough and will bend considerably before breaking, even when heated red or white hot. Nichrome in Cast Iron: Because of the irregularity of the castings, the numerous cores required, and the necessity for sound castings, gray iron with a high silicon content has been the best cast iron available to the automotive industry. Attempts have been made to alloy this metal in such a way that the strength and hardness would be increased, but con- siderable difficulty has been experienced in obtaining uniform results. Nickel has been added to the cupola with success, but in the case of automotive castings, where a large quantity of silicon is present, the nickel has combined with the silicon in forming large flakes of graphite, which, of course, softens the product. To offset this, chromium has also been added, but it has been uncertain just what the chromium content of the poured mixture should be, as a considerable amount of the chromium oxidizes. Nichrome (Grade B) may be added to the ladle to obtain chromium and nickel in definite controllable amounts. The analysis of this nichrome is, approximately: Nickel, 60 per cent; chromium, 12 per cent; and iron, 24 per cent. It is claimed that the process produces cast- ings of closer grain, greater hardness, greater resistance to abrasion, increased durability, improved machinability, and decreased brittleness. Nichrome-processed iron is suitable for casting internal-combustion engine cylinders; electrical equipment, where a control of the magnetic properties is desired; cast-iron cams; iron castings of thin sections where machinability and durability are factors; electrical resistance grids; pistons; piston-rings; and water, steam, gas, and other valves. Nickel Alloy for Resisting Acids.—The resistance of nickel to acids is considerably increased by an addition of tantalum. Ordinarily from 5 to 10 per cent may be added, but the resistance increases with an increasing percentage of tantalum. An alloy of nickel with 30 per cent tantalum, for example, can be boiled in aqua regia or any other acid without being affected. The alloy is claimed to be tough, easily rolled, capable of being hammered or drawn into wire. The nickel loses its magnetic quality when alloyed with tantalum. The alloy can be heated in the open air at a high temperature without oxidizing. The method of producing the alloy consists in mixing the two metals in a powdered form, compressing them at high pressure, and bringing them to a high heat in a crucible or quartz tube in a vac- uum. For general purposes, the alloy is too expensive. Duronze.—An alloy of high resistance to wear and corrosion, composed of aluminum, copper, and silicon, with a tensile strength of 90,000 pounds per square inch. Developed for the manufacture of valve bushings for valves that must operate satisfactorily at high pressures and high temperatures without lubrication. Machinery's Handbook 27th Edition Copyright 2004, Industrial Press, Inc., New York, NY 3038 MATERIALS Aluminum Alloys, Wrought, Sheet.—Physical Properties: In the form of sheets, the tensile strength varies from 35,000 for soft temper to 62,000 pounds per square inch for heat-treated sheets, and the elongation in 2 inches from 12 to 18 per cent. The yield strength of a heat-treated sheet is about 40,000 pounds per square inch minimum. Plow-steel Wire Rope.—The name “plow” steel originated in England and was applied to a strong grade of steel wire used in the construction of very strong ropes employed in the mechanical operation of plows. The name “plow” steel, however, has become a commer- cial trade name, and, applied to wire, simply means a high-grade open-hearth steel of a ten- sile strength in wire of from 200,000 to 260,000 pounds per square inch of sectional area. A strength of 200,000 pounds per square inch is obtained in wire about 0.200 inch in diam- eter. Plow steel when used for wire ropes has the advantage of combining lightness and great strength. It is a tough material, but not as pliable as crucible steel. The very highest grade of steel wire used for wire rope is made from special steels ranging in tensile strength in wire from 220,000 to 280,000 pounds per square inch of sectional area. This steel is especially useful when great strength, lightness, and abrasive resisting qualities are required. Type Metal.—Antimony gives to metals the property of expansion on solidification, and hence, is used in type metal for casting type for the printing trades to insure completely fill- ing the molds. Type metals are generally made with from 5 to 25 per cent of antimony, and with lead, tin and sometimes a small percentage of copper as the other alloying metals. The compositions of a number of type metal alloys are as follows (figures given are per- centages): lead 77.5, tin 6.5, antimony 16; lead 70, tin, 10, antimony 18, copper, 2; lead 63.2, tin 12, antimony 24, copper 0.8 ; lead 60.5, tin 14.5, antimony 24-25, copper 0.75; lead 60, tin 35, antimony 5; and lead 55.5, tin 40, antimony 4.5. A high grade of type metal is composed of the following percentages: lead 50; tin 25; and antimony 25. Vanadium Steel.— The two most marked characteristics of vanadium steel are its high tensile strength and its high elastic limit. Another equally important characteristic is its great resistance to shocks; vanadium steel is essentially a non-fatigue metal, and, there- fore, does not become crystallized and break under repeated shocks like other steels. Tests of the various spring steels show that, when subjected to successive shocks for a consider- able length of time, a crucible carbon-steel spring was broken by 125,000 alternations of the testing machine, while a chrome-vanadium steel spring withstood 5,000,000 alterna- tions, remaining unbroken. Another characteristic of vanadium steel is its great ductility. Highly-tempered vanadium-steel springs may be bent sharply, in the cold state, to an angle of 90 degrees or more, and even straightened again, cold, without a sign of fracture; vana- dium-steel shafts and axles may be twisted around several complete turns, in the cold state, without fracture. This property, combined with its great tensile strength, makes vanadium steel highly desirable for this class of work, as well as for gears which are subjected to heavy strains or shocks upon the teeth. Chromium gives to steel a brittle hardness which makes it very difficult to forge, machine, or work, but vanadium, when added to chrome- steel, reduces this brittle hardness to such an extent that it can be machined as readily as an 0.40-per-cent carbon steel, and it forges much more easily. Vanadium steels ordinarily contain from 0.16 to 0.25 per cent of vanadium. Steels of this composition are especially adapted for springs, car axles, gears subjected to severe service, and for all parts which must withstand constant vibration and varying stresses. Vanadium steels containing chro- mium are used for many automobile parts, particularly springs, axles, driving-shafts, and gears. Wood’s Metal.—The composition of Wood’s metal, which is a so-called “fusible metal,” is as follows: 50 parts of bismuth, 25 parts of lead, 12.5 parts of tin and 12.5 parts of cad- mium. The melting point of this alloy is from 66 to 71 degrees centigrade (151 to 160 degrees F. approximately). Machinery's Handbook 27th Edition Copyright 2004, Industrial Press, Inc., New York, NY MATERIALS 3039 Lumber.—Lumber is the product of the saw and planing mill not further manufactured than by sawing, resawing, and passing lengthwise through a standard planing machine, cross-cutting to length and working. When not in excess of one-quarter inch thickness and intended for use as veneering it is classified as veneer. According to the Simplified Practice Recommendations promulgated by the National Bureau of Standards, lumber is classified by its principal use as: yard lumber, factory and shop lumber, and structural lumber. Yard lumber is defined as lumber of all sizes and patterns which is intended for general building purposes. Its grading is based on intended use and is applied to each piece without reference to size and length when graded and without consideration to further manufac- ture. As classified by size it includes: strips, which are yard lumber less than 2 inches thick and less than 8 inches wide; boards, which are yard lumber less than 2 inches thick but 8 inches or more wide; dimension, which includes all yard lumber except strips, boards and timbers; and timbers, which are yard lumber of 5 or more inches in the least dimension. Factory and shop lumber is defined as lumber intended to be cut up for use in further manufacture. It is graded on the basis of the percentage of the area which will produce a limited number of cuttings of a specified, or of a given minimum, size and quality. Structural lumber is defined as lumber that is 2 or more inches thick and 4 or more inches wide, intended for use where working stresses are required. The grading of structural lum- ber is based on the strength of the piece and the use of the entire piece. As classified by size and use it includes joists and planks—lumber from 2 inches to but not including 5 inches thick, and 4 or more inches wide, of rectangular cross section and graded with respect to its strength in bending, when loaded either on the narrow face as joist or on the wide face as plank; beams and stringers—lumber of rectangular cross section 5 or more inches thick and 8 or more inches wide and graded with respect to its strength in bending when loaded on the narrow face; and posts and timbers—pieces of square or approximately square cross section 5 by 5 inches and larger and graded primarily for use as posts or columns carrying longitudinal load, but adapted to miscellaneous uses in which strength in bending is not especially important. Lumber, Manufactured.—According to the Simplified Practice Recommendations pro- mulgated by the National Bureau of Standards, lumber may be classified according to the extent which It Is manufactured as: Rough lumber which is lumber that is undressed as it comes from the saw. Surfaced lumber which is lumber that is dressed by running it through a planer and may be surfaced on one or more sizes and edges. Worked lumber which is lumber that has been run through a matching machine, sticker or molder and includes: matched lumber which has been worked to provide a close tongue- and-groove joint at the edges or, in the case of end-matched lumber, at the ends also; ship- lapped lumber which has been worked to provide a close rabbetted or lapped joint at the edges; and patterned lumber which has been shaped to a patterned or molded form. Lumber Water Content.—The origin of lumber has a noticeable effect on its water con- tent. Lumber or veneer (thin lumber produced usually by rotary cutting or flat slicing, sometimes by sawing), when produced from the log, contains a large proportion of water, ranging from 25 to 75 per cent of the total weight. One square foot (board measure, one inch thick) of gum lumber, weighing approximately five pounds when sawed, will be reduced to about three pounds when its water content of approximately one quart has been evaporated. Oak grown on a hillside may contain only a pint (approximately 1 lb.) and swamp gum may have from 2 to 4 pints of water per square foot, board measure. This water content of wood exists in two forms—free moisture and cell moisture. The former is readily evaporable in ordinary air drying, but the latter requires extensive air drying (sev- eral years) or artificial treatment in kilns. It is possible to use artificial means to remove the free moisture, but a simple air exposure is usually more economical. Machinery's Handbook 27th Edition Copyright 2004, Industrial Press, Inc., New York, NY 3040 DIMENSIONING Dimensioning, Gaging, and Measuring Transfer Calipers.—Calipers provided with an auxiliary arm which can be located so that the calipers may be opened or closed to the original setting, if required. Calipers of this type are generally used for inside measurements, and are employed for measuring recesses where it is necessary to move the caliper points in order to remove the calipers from the place where the measurement is taken. Wheatstone Bridge.—The most generally used method for the measurement of the ohmic resistance of conductors is by the use of the Wheatstone bridge. In a simple form (See Fig. 1.) it comprises two resistance coils the ratio of the resistances of which is known, and a third, generally adjustable, resistance of known value. These are connected in circuit with the unknown resistance to be measured, a galvanometer, and a source of current, as in the diagram. Fig. 1. Wheatstone Bridge The adjustable resistance and the “bridge arms,” if necessary, are adjusted until the gal- vanometer indicates no flow of current. The value of the unknown resistance is thus mea- sured in terms of the known resistance and the known ratio of the bridge arms. In the diagram, R 1 , R 2 , R 3 , and R 4 are resistances, B a source of electromotive force and I 1 , I 2 , I 3 and 1 4 currents through the resistances; G is a galvanometer. If the relation of the various resistances is such that no current flows through G, then I 1 equals I 2 , and I 3 equals I 4 ; also 1 1 R 1 equals 1 3 R 3 , and 1 2 R 2 equals 1 4 R 4 , there being no electromotive forces in the triangles R 1 R 3 G and R 2 R 4 G. It follows, therefore, that and hence, as If one of these resistances, R 1 for instance, is unknown, it may then be found through the equation: I 1 I 3 R 3 R 1 ,= and I 2 I 4 R 4 R 2 = I 1 I 3 I 2 I 4 ,= it follows that R 3 R 1 R 4 R 2 = Machinery's Handbook 27th Edition Copyright 2004, Industrial Press, Inc., New York, NY TOOLING 3041 Wheatstone bridges are made in many forms. The three known resistances are made adjustable and are usually made of many spools of special resistance wire. The resistances are usually varied by short-circuiting a greater or smaller number of these spools. Tools and Tooling Rotary Files and Burs.—Rotary files and burs are used with power-operated tools, such as flexible- or stationary-shaft machines, drilling machines, lathes, and portable electric or pneumatic tools, for abrading or smoothing metals and other materials. Corners can be bro- ken and chamfered, burs and fins removed, holes and slots enlarged or elongated, and scale removed in die-sinking, metal patternmaking, mold finishing, toolmaking and casting operations. The difference between rotary files and rotary burs, as defined by most companies, is that the former have teeth cut by hand with hammer and chisel, whereas the latter have teeth or flutes ground from the solid blank after hardening, or milled from the solid blank before hardening. (At least one company, however prefers to differentiate the two by use and size: The larger-sized general purpose tools with 1 ⁄ 4 -inch shanks, whether hand cut or ground, are referred to as rotary files; the smaller shanked – 1 ⁄ 8 -inch – and correspondingly smaller- headed tools used by diesinkers and jewelers are referred to as burs.) Rotary files are made from high-speed steel and rotary burs from high-speed steel or cemented carbide in various cuts such as double extra coarse, extra coarse or rough, coarse or standard, medium, fine, and smooth. Standard shanks are 1 ⁄ 4 inch in diameter. There is very little difference in the efficiency of rotary files or burs when used in electric tools and when used in air tools, provided the speeds have been reasonably well selected. Flexible-shaft and other machines used as a source of power for these tools have a limited number of speeds which govern the revolutions per minute at which the tools can be oper- ated. The carbide bur may be used on hard or soft materials with equally good results. The principal difference in construction of the carbide bur is that its teeth or flutes are provided with negative rather than a radial rake. Carbide burs are relatively brittle and must be treated more carefully than ordinary burs. They should be kept cutting freely, in order to prevent too much pressure, which might result in crumbling of the cutting edges. At the same speeds, both high-speed steel and carbide burs remove approximately the same amount of metal. However, when carbide burs are used at their most efficient speeds, the rate of stock removal may be as much as four times that of ordinary burs. It has been demonstrated that a carbide bur will last up to 100 times as long as a high-speed steel bur of corresponding size and shape. Tooth-rest for Cutter Grinding.—A tooth-rest is used to support a cutter while grinding the teeth. For grinding a cylindrical cutter having helical or "spiral" teeth, the tooth-rest must remain in a fixed position relative to the grinding wheel. The tooth being ground will then slide over the tooth-rest, thus causing the cutter to turn as it moves longitudinally, so that the edge of the helical tooth is ground to a uniform distance from the center, through- out its length. For grinding a straight-fluted cutter, it is also preferable to have the tooth- rest in a fixed position relative to the wheel, unless the cutter is quite narrow, because any warping of the cutter in hardening will result in inaccurate grinding, if the toothrest moves with the work. The tooth-rest should be placed as close to the cutting edge of the cutter as is practicable, and bear against the face of the tooth being ground. R 1 R 2 R 3 R 4 = Machinery's Handbook 27th Edition Copyright 2004, Industrial Press, Inc., New York, NY 3042 MACHINING OPERATIONS Machining Operations Feed Rate on Machine Tools.— The rate of feed as applied to machine tools in general, usually indicates (1) the movement of a tool per work revolution, (2) the movement of a tool per tool revolution, (3) or the movement of the work per tool revolution. Rate of Feed in Turning: The term "feed" as applied to a lathe indicates the distance that the tool moves during each revolution of the work. There are two ways of expressing the rate of feed. One is to give the actual tool movement per work revolution in thousandths of an inch. For example, the range of feeds may be given as 0.002 to 0.125 inch. This is the usual method. Another way of indicating a feed range is to give the number of cuts per inch or the number of ridges that would be left by a pointed tool after turning a length of one inch. For example, the feed range might be given as 8 to 400. In connection with turning and other lathe operations, the feed is regulated to suit the kind of material, depth of cut, and in some cases the finish desired. Rate of Feed in Milling: The feed rate of milling indicates the movement of the work per cutter revolution. Rate of Feed in Drilling: The rate of feed on drilling machines ordinarily indicates the feeding movement of the drill per drill revolution. Rate of Feed in Planing: On planers, the rate of feed represents the tool movement per cutting stroke. On shapers, which are also machines of the planing type, the rate of feed represents the work movement per cutting stroke. Rate of Feed on Gear Hobb era: The feed rate of a gear hobbing machine represents the feeding movement of the hob per revolution of the gear being hobbed. Feed on Grinding Machines:: The traversing movement in grinding is equivalent to the feeding movement on other types of machine tools and represents either the axial move- ment of the work per work revolution or the traversing movement of the wheel per work revolution, depending upon the design of the machine. Billet.—A “billet,” as the term is applied in rolling mill practice, is square or round in sec- tion and from 1 1 ⁄ 2 inches in diameter or square to almost 6 inches in diameter or square. Rolling mills used to prepare the ingot for the forming mills are termed “blooming mills,” “billet mills,” etc. Milling Machines, Lincoln Type.—The well-known Lincoln type of milling machine is named after George S. Lincoln of the firm then known as George S. Lincoln & Co., Hart- ford, Conn. Mr. Lincoln, however, did not originate this type but he introduced an improved design. Milling machines constructed along the same general lines had previ- ously been built by the Phoenix Iron Works of Hartford, Conn., and also by Robbins & Lawrence Co., of Windsor, Vt. Milling machines of this class are intended especially for manufacturing and are not adapted to a great variety of milling operations, but are designed for machining large numbers of duplicate parts. Some milling machines which are designed along the same lines as the Lincoln type are referred to as the manufacturing type. The distinguishing features of the Lincoln type are as follows: The work table, instead of being carried by an adjustable knee, is mounted on the solid bed of the machine and the outer arbor support is also attached directly to the bed. This construction gives a very rigid support both for the work and the cutter. The work is usually held in a fixture or vise attached to the table, and the milling is done as the table feeds longitudinally. The table is not adjustable vertically but the spindle head and spindles can be raised or lowered as may be required. Saddle.—A machine tool saddle is a slide which is mounted upon the ways of a bed, cross- rail, arm, or other guiding surfaces, and the saddle metal-cutting tools or a work-holding table. On holding either metal-cutting tools or a work-holding table. On a knee-type mill- ing machine the saddle is that part which slides upon the knee and which supports the work-holding table. The saddle of a planer or boring mill is mounted upon the cross-rail Machinery's Handbook 27th Edition Copyright 2004, Industrial Press, Inc., New York, NY MACHINING OPERATIONS 3043 and supports the tool-holding slide. The saddle of a lathe is that part of a carriage which slide. The saddle of a lathe is that part of a carriage which slides directly upon the lathe bed and supports the cross-slide. Cold Extrusion.—In simplest terms, cold extrusion can be defined as the forcing of unheated metal to flow through a shape-forming die. It is a method of shaping metal by plastically deforming it under compression at room temperature while the metal is within a die cavity formed by the tools. The metal issues from the die in at least one direction with the desired cross-sectional contour, as permitted by the orifice created by the tools. Cold extrusion is always performed at a temperature well below the recrystallization temperature of the metal (about 1100 to 1300 degrees F. for steel) so that work-hardening always occurs. In hot extrusion, recrystallization eliminates the effects of work-hardening, unless rapid cooling of the extrusion prevents recrystallization from being completed. Extrusion differs from other processes, such as drawing, in that the metal is always being pushed under compression and never pulled in tension. As a result, the material suffers much less from cracking. While coining is closely related to extrusion, it differs in that metal is completely confined in the die cavity instead of being forced through openings in the die. Some forging operations combine both coining and extrusion. The pressure of the punch against the metal in an open die, and the resultant shaped part obtained by displacing the metal along paths of least resistance through an orifice formed between the punch and die, permits considerably higher deformation rates without tearing and large changes in the shape. Extrusion is characterized by a thorough kneading of the material. The cross-sectional shape of the part will not change due to expansion or contrac- tion as it leaves the tool orifice. The term "cold extrusion" is not too descriptive and is not universally accepted. Other names for the same process include impact extrusion, extru- sion-forging, cold forging, extrusion pressing, and heavy cold forming. Impact extrusion, however, is more frequently used to describe the production of non-ferrous parts, such as collapsible tubes and other components, while cold extrusion seems to be preferred by manufacturers of steel parts. In Germany, the practice is called Kaltspritzen-a literal trans- lation of which is "cold-squirting." One probable reason for not using impact extrusion in referring to the cold extrusion of steel is that the term implies plastic deformation by striking the metal an impact blow. Actually, the metal must be pushed through the die orifice, with pressure required over a definite period of time. One disadvantage of the terminology "cold extrusion" is the possi- ble confusion with the older, more conventional direct extrusion process in which billets of hot metal are placed in a cylinder and pushed by a ram through a die (usually in a large, horizontal hydraulic press) to form rods, bars, tubes, or irregular shapes of considerable length. Another possible disadvantage is the connotation of the word "cold." While the process is started with blanks, slugs, tubular sections, or pre-formed cups at room temperature, the internal, frictional resistance of the metal to plastic flow raises the surface temperature of the part to 400 degrees F. or more, and the internal temperature even higher (depending on the severity of the operation). These are still below the recrystallization temperature and the extrusions retain the advantages of improved physical properties resulting from the cold working. Transfer Machines.—These specialized machine tools are used to perform various machining operations on parts or parts in fixtures as the parts are moved along on an auto- matic conveyor which is part of the machine tool set-up. In a set-up, the parts can move in a straight line from their entry point to their exit point, or the setup may be constructed in a U-shape so that the parts are expelled near where they start. Machinery's Handbook 27th Edition Copyright 2004, Industrial Press, Inc., New York, NY [...]... Machinery’s Handbook 27th Edition BY JOHN M AMISS, FRANKLIN D JONES, AND HENRY H RYFFEL CHRISTOPHER J MCCAULEY, EDITOR RICCARDO HEALD, ASSOCIATE EDITOR MUHAMMED IQBAL HUSSAIN, ASSOCIATE EDITOR 20 04 INDUSTRIAL PRESS INC NEW YORK Copyright 20 04, Industrial Press, Inc., New York, NY Guide to Machinery's Handbook 27th Edition COPYRIGHT 193 1, 193 9, 195 1, 19 54, © 195 9, © 19 64, © 196 8, © 197 1,© 197 5, © 198 0, © 19 84, ... flywheel speed.) 11) The tables beginning on Handbook page 99 0 give lengths of chords for spacing off circumferences of circles into equal parts Is another method available? Copyright 20 04, Industrial Press, Inc., New York, NY Guide to Machinery's Handbook 27th Edition SECTION 2 CHORDAL DIMENSIONS, SEGMENTS, AND SPHERES HANDBOOK Pages 78, 71, and 98 9— 99 1 A chord of a circle is the distance along a... handbook 27th guide Cover title: Machinery’s handbook twenty seventh guide This book should be used in conjunction with the twenty-seventh edition of Machinery’s Handbook ISBN 0-8311-2 799 -6 ISBN 0-8311-2788-0 (electronic edition with math) 1 Mechanical engineering Handbook, manuals, etc I Title: Machinery’s handbook 27 guide II Machinery’s handbook twenty seventh guide III Jones, Franklin Day, 18 79- 196 7... 20 04, Industrial Press, Inc., New York, NY Guide to Machinery's Handbook 27th Edition 2 DIMENSIONS AND AREAS OF CIRCLES 251.328 + 2 × 50.2656 = 351.8 592 square inches The same result could have been obtained by using the formula for total area given on Handbook page 76: A = 3. 141 6 × d × (1⁄2 d + h) = 3. 141 6 × 8 × (1⁄2 × 8 + 10) = 351.8 592 square inches Example 4: If the circumference of a tree is 96 ... 198 8, © 199 2, © 199 6, © 2000, © 20 04 by Industrial Press Inc., New York, NY Library of Congress Cataloging-in-Publication Data Amiss, John Milton, 1887- 196 8 Guide to the use of tables and formulas in Machinery’s Handbook, 27th edition by John M Amiss, Franklin D Jones, and Henry H Ryffel; Christopher J McCauley, editor; Riccardo Heald, associate editor; Muhammed Iqbal Hussain, associate editor 2 64. .. given the formula: Volume = 0.5236d3 The cube of 245 ⁄8 = 14, 93 2.3 69; hence, the volume of this sphere = 0.5236 × 14, 93 2.3 69 = 7818.5 cubic inches PRACTICE EXERCISES FOR SECTION 2 (See Answers to Practice Exercises For Section 2 on page 221) 1) Find the lengths of chords when the number of divisions of a circumference and the radii are as follows: 30 and 4; 14 and 21⁄2; 18 and 31⁄2 2) Find the chordal distance... 0 .48 8 square inch Example 4: A cylindrical oil tank is 41 ⁄2 feet in diameter, 10 feet long, and is in a horizontal position When the depth of the oil is 3 feet, 8 inches, what is the number of gallons of oil? The total capacity of the tank equals 0.78 54 × (41 ⁄2)2 × 10 = 1 59 cubic feet One U.S gallon equals 0.1337 cubic foot (see Handbook page 2566); hence, the total capacity of the tank equals 1 59 ÷... 3-inch diameter workpiece ( 1 4- foot diameter) and for a cutting speed of 40 fpm, rpm = 40 ÷ (3. 141 6 × 1 4) = 50 .92 = 51 rpm, approximately, which is the same as the value given on page 1018 of the Handbook PRACTICE EXERCISES FOR SECTION 1 (See Answers to Practice Exercises For Section 1 on page 221) 1) Find the area and circumference of a circle 10 mm in diameter 2) On Handbook page 1020, for a 5-mm... Information 108 14 Standard Screw And Pipe Threads 113 15 Problems In Mechanics 122 16 Strength Of Materials 138 17 Design Of Shafts And Keys For Power Transmission 150 18 Splines 1 59 19 Problems In Designing And Cutting Gears 1 69 20 Cutting Speeds, Feeds, And Machining Power 196 21 Numerical Control 205 22 General Review Questions 212 23 Answers To Practice Exercises INDEX 221 2 54 vi Copyright 20 04, Industrial... circle: π = 3. 141 592 65… = circumference of circle -diameter of circle For most practical purposes the value of π = 3. 141 6 may be used Example 1:Find the circumference and area of a circle whose diameter is 8 inches On Handbook page 66, the circumference C of a circle is given as 3. 141 6d Therefore, 3. 141 6 × 8 = 25.1328 inches On the same page, the area is given as 0.7854d2 Therefore, . I 2 I 4 R 4 R 2 = I 1 I 3 I 2 I 4 ,= it follows that R 3 R 1 R 4 R 2 = Machinery's Handbook 27th Edition Copyright 20 04, Industrial Press, Inc., New York, NY TOOLING 3 041 Wheatstone. from 45 ,000 to 50,000 pounds per square inch. The ultimate strength at 200 degrees F. is 94 , 000 pounds per square inch; at 40 0 degrees F., 91 ,000 pounds per square inch; at 600 degrees F., 59, 000. Committee, of the April 1 94 1 draft. The revision was approved by the sponsors and ASA and published as an American Standard in October, 1 94 2 . Shortly after publication of the 1 94 2 standard, the Committee