Publisher's Note: Products purchased from Third Party sellers are not guaranteed by the publisher for quality, authenticity, or access to any online entitlements included with the product. It provides clear, concise answers to thousands of mechanical engineering questions. Impurities may cause various colours and tints. KILLED STEEL — Steel that has been deoxidized with agents such as silicon or aluminium to reduce the oxygen content to such a level that no reaction occurs between carbon and oxygen during solidification.
This prevents gases from evolving during solidification. LAMINATE — 1 A composite metal, usually in the form of sheet or bar, composed of two or more metal layers so bonded that the composite metal forms a structural member.
A device in which heat is derived from the intense coherent beam of laser light energy. This intense, narrow beam of light is used in some welding and machining operations. LEAD — Heavy, bluish grey, soft, ductile metal, which has a specific gravity of LEAD SCREEN — In radiography, a screen is used 1 to filter out soft wave or scattered radiation and 2 to reduce the intensity of the remaining radiation so that the exposure time can be decreased.
The austenite decomposes into ferrite and cementite on cooling below the transformation temperature. LIGNIN — A substance that is related to cellulose, that with cellulose forms the woody cell walls of plants and the material that cements them together.
Methyl alcohol is derived from lignin in the destructive distillation of wood. LOAM — Clayey sand mixture having the consistency of slime, and used in the making of moulds and cores for heavy castings. LUTE — Fine adhesive composition of substances such as clay, sharp sand, plumbago and horsedung tempered with water. Used for sealing joints in moulds and cores, for the purpose of making them air or metal tight.
Widely used for aircraft components, their weight is only two thirds that of aluminium, and a quarter of that of steel. The graphite is in the form of temper carbon. This is less brittle than gray cast iron. Martensite is the hardest of the transformation products of austenite, having an acicular or needle like microstructure. The three forms of matter are solids, liquids and gases. Examples are sulphur, silicon, carbon, phosphorous and arsenic. It gives red hardness and increases the strength of steel at high temperatures.
It increases the corrosion resistance of stainless steels at high temperatures, increases the machinability of carbon steels and reduces the temper brittleness of aluminium steels. MU METAL — Special alloy of nickel and iron, also containing copper and manganese, requiring only a very small magnetizing force to produce a normal flux density i. MYCALEX — It is the trade name for a ceramic product made up of glass- bonded mica flakes that possess a combination of properties found in other insulating materials.
Crude rubber is coagulated by heat or by addition of electrolytes. Used for under-water fittings of marine craft. NICHROME — Alloy of nickel and chromium which is practically non- corrosive, can withstand high temperature without oxidation and is used for furnace components.
Therefore, used in pure form for some applications, such as plating. It is more usually alloyed with other metals. Class of alloys used in the manufacture of electrical resistance coils and elements, decorative articles for which its lustrous colour which increases in whiteness with nickel content make it very suitable, or for heavy duty works such as high pressure steam fittings. The commonly used grades contain 0. NOMAG — Non-magnetic cast iron, used for castings in electric motors and alternators and similar applications.
NUCLEUS — 1 The first structurally stable particle capable of initiating recrystallization of a phase or the growth of a new phase and possessing an interface with the parent matrix. NYLON — A group of plastics of nitrogenous structure known as polyamides which are crystalline in nature and can be so processed as to orient the crystals axially thus making the tensile strength of fibres extremely high.
ORE — A natural mineral that may be mined and treated for the extraction of any of its components, metallic or otherwise. PHASE — It is a portion of matter which is homogeneous in the sence that its smallest adjacent parts are indistinguishable from one another. PHASE DIAGRAM — Phase diagram is also called equilibrium diagram or constitution diagram, indicates the relative amount and composition of phases present in an alloy at a given temperature and pressure, when the alloy is in equilibrium.
Its formula weight is Used as bearing material. PHOTON — The smallest possible quantity of an electromagnetic radiation that can be characterized by a definite frequency. PIG IRON — Iron produced from iron ore in the blast furnace, basic raw material from which all cast iron, wrought iron and steel are made. Usually contains about 4. Plasma arcs are used in welding, cutting and machining processes. It is extensively used, either solid or clad, for chemical equipment.
In combination with glass fibres they form a product which has an outstanding strength- weight ratio. POLYMER — A chemical compound or mixture of compounds formed by polymerization and consisting essentially of repeating structural units. It is found in nature as radium , which has a half-life of years. These materials are usually silica, fire clay, diaspore, alumina and kaolin.
They are used for furnace linings. RESIDUE — The material that remains after completion of a chemical or physical process, such as combustion, distillation, evaporation or filtration. When the mould top is not capped, a side and bottom rim of several centimeters forms. The solidified ingot has got scattered blow holes and porosity in the center but a relatively thick skin free from blow holes. RUST — A corrosion product containing hydrated oxide of iron. Applied only to ferrous alloys.
SAND moulding — Substance used in foundries for making the moulds. These contain a few electrons to give them conductivity intermediate between metals and insulators. SILMANAL — It is the name given to a rather expensive alloy of silver, manganese, and aluminium that has unusual magnetic properties for special applications. SLAG — The more or less completely fused and vitrified matter separated during the reduction of a metal from its ore.
Also a mixture of fog and smoke. Particles suspended in air after incomplete combustion of materials containing carbon. The matter in the exhaust emission which obscures the transmission of light. Soft solder is an alloy of lead and tin, in which the proportions of the two constituents may vary from almost pure lead to almost pure tin.
The alloy steels contain substantial amounts of alloying elements such as chromium or nickel besides carbon. THERMIT — Powdered form of finely divided iron oxide and aluminium which burns intensely to produce superheated liquid steel at a temperature of about TIN — A silvery white, soft metal used in solders and as a plating material. TOOL STEEL — A special group of steels that is designed to specific uses, such as heat resistant steels that can be heat treated to produce certain properties mainly hardness and wear resistance.
Used as an alloying element in high speed steel. Usually contains less than 0. It is tough, malleable, and relatively soft. Rolled steel is strongest in the direction of rolling. BEL — A unit denoting the ratio of power levels of signals or sound. The number of bels may be given as the common logarithm of the ratio of powers.
A number is derived by measuring the indentation with a special microscope. Brittleness is opposite to plasticity. It is one type of crystalline fracture. COUPON — A piece of metal from which a test specimen is to be prepared, often an extra piece as on a casting or forging. CREEP — Slow plastic deformation in steel and most structural metals caused by prolonged stress under the yield point at elevated temperatures. More accurately defined as the amount of work dissipated into heat by a unit volume of material during a completely reverse cycle of unit stress.
DUCTILITY — The property of a material to deform permanently or to exhibit plasticity, elongation or bending or twisting without rupture breaking or cracking while under tension. In mild steel, the fatigue strength is about 50 per cent of the tensile strength. It forms a body centered cube lattice and may hold in solution considerable amounts of silicon, nickel or phosphorous.
Usually refers to unnotched tensile specimens. GRAIN SIZE — For metals, a measure of the area or volume of grains in polycrystalline material, usually expressed as an average when the individual sizes are fairly uniform. Reported in terms of number of grains per unit area or volume, average diameter, or as a grain size number derived from area measurements. GROWTH — With reference to cast iron, permanent increase in volume that results from continued or repeated cyclic heating and cooling at elevated temperatures.
This is divided into three categories, resistance to penetration, resistance to abrasion and elastic hardness. The presence of excess amounts of sulphur in steel causes hot shortness. This test determines the notch toughness of a metal. KISH — Graphite thrown out by liquid cast iron in cooling. For example, the sites of atoms in a crystal.
The points of the three dimensional space lattice are constructed by the repeated application of the basic translations that carry a unit cell into its neighbour.
LIQUIDUS — The temperature at which freezing begins during cooling and ends during heating under equilibrium conditions, represented by a line on a two phase diagram. Ratio of stress, within proportional limit, to corresponding strain. In metals, over oxidation during heating under oxidizing conditions often results in permanent damage to metals.
PH — The negative logarithm of the hydrogen ion activity. It denotes the degree of acidity or basicity of a solution. PERMANENT SET — When a metal remains deformed from its original dimensions after the forces applied to it have been reduced to zero, it is said to have undergone plastic deformation, and the amount of deformation is called the permanent set.
The following phases occur in the iron carbon alloy, molten alloy; austenite, ferrite, cementite, and graphite. The direction of the strain is dependant upon the polarity of the field. Clay is completely a plastic material. Metals exhibit plasticity in varying amounts. The proportional limit is high for steels and low for cast iron, copper, and aluminium.
Several scales are used to cover very soft to very hard materials. The Rockwell C scale is used mostly for steel.
SHEARING — A concentration of forces in which the bending moment is virtually zero and the metal tends to tear or to be cut along a transversal axis at the point of applied pressure. It is designated as cold, hot and red to indicate the temperature range in which the brittleness occurs.
SLAG dross — A fused product that occurs in the melting of metals and is composed of oxidized impurities of a metal and a fluxing substance such as limestone. The slag protects the metal from oxidation by the atmosphere since it floats on the surface of the molten metal.
These are lines that appear on the polished surface of a plastically deformed metal. The slip bands are the result of crystal displacement, defining planes in which shear has taken place. Some of the types of solid solutions are continuous, intermediate, interstitial, substitutional and terminal. SOLIDUS — Seen as a line in a two phase diagram, it represents the temperatures at which freezing ends when cooling, or melting begins when heating under equilibrium conditions.
The specific gravity for pure water is taken as 1. An aggregate of globular carbide is formed from other microstructures such as pearlite.
For identical shapes, the stiffness is proportional to the modulus of elasticity. This is unit deformation of a metal when stress is applied. It is called tensile, compressive, or shear strength depending on the load.
The force tends to cause the plane of the area involved to slide on the adjacent planes. Stress raisers pose a particular problem and can cause early failure in members that are subjected to many cycles of stress reversals. This treatment is used to relieve stresses caused by welding, cold working, machinning, casting and quenching. An alloy may be cold worked to the hard temper, fully softened to the anealed temper, or two intermediate tempers.
All materials are in some measure conductors of heat. The difference of expansion and contraction between the interior and exterior surfaces of a metal that is being heated or cooled is an example. Work per unit volume required to fracture a metal and is equal to the area under the stress strain curve. The highest strength that a metal exhibits after it begins to deform plastically under load.
Rupture of the material occurs either at the peak of its ultimate strength or at a point of further elongation and at a drop in stress load. The inert gases have zero valence, valence is determined by considering the positive and negative atoms as determined by the atoms gaining or losing of valence electrons.
VISCOSITY — The property of the fluids, either liquid or gaseous, which causes them to resist instantaneous change of shape or instantaneous rearrangement of their parts, due to internal friction. VOID — A cavity or hole in a substance. WEAR — A surface deterioration of contacting surfaces that destroys their operating relationship, or causes rupture if carried far enough. This phenomenon is not seen in non-ferrous metals and other alloy steels. BENDING by forging — In bending there is a thinning of the material, accompanied by a spreading of the metal on the inside of the bend and a narrowing at the outside.
The hole material is saved and used for further operation. BROACHING — Consecutive shearing of a hole or contour by a series of stepped cutting edges similar to a saw used in low acting presses for accurate sizing of holes or contours, such as gear teeth, and keyways. Strain hardening occurs as a result of this permanent deformation.
In this, the metal is ultimately confined in all directions, being forced to behave as pasty fluid in filling every portion of the confining cavity. The mould or moulds is rotated about a centre where molten metal is poured and allowed to follow sprues outward and get into the mould cavity. With this method, a thin sheet of more expensive metal or one less likely to corrode may be applied to a less expensive metal or one more likely to corrode.
Often used to gather metal as for stovepipe joints. CROWNING — Shaping of the rim of a belt pulley so that the diameter at the centre of the face is greater than at the edges so as to keep the belt on the crown of the pulley. In solids, it is a slow movement of atoms from areas of high concentration towards areas of low concentration.
The process may be a migration of interstitial atoms such as carbon, b movement of vacancies or c direct exchange of atoms to neighbouring sites.
DRAWING — Process, in press work, which involves reducing the diameter or cross-sectional dimensions of a cup, shell, tube, bar or wire. DROP FORGING — Drop forging is the operation in which a metal part is formed by repeated hammer blows on a bar or billet placed between a pair of dies containing the impression of the finished shape desired.
Here the metal is displaced to the desired shape by striking it between two dies. As the dies strike, the stock, metal is gathered toward the center of the cavity and some sideways movement also takes place. EXTRUSION — Process in which metal often heated is caused to flow through a restricted orifice by using an extremely high force, so creating an extremely elongated strip of uniform, but comparatively small cross-section.
A filament of the fibre is wound around a form, then bonded in place with the resin matrix. A flange may drawn on a shell or a tube. FLASH WELDING — Method of electric resistance welding of sections of material by the formation of an electric arc between the edges of the pieces to be joined and then pressing together with a light pressure the molten edges.
FLATTING — Finishing operation carried out at the end of the work cycle to remove the various hammer marks on the surface left in by the previous shaping operations. FORGING — A method of metal working in which the metal is hammered into the desired shape, or is forced into a mould by pressure or hammering, usually after being heated to a more plastic state.
Hot forging requires less force to form a shape than that of cold forging, which is usually done at room temperature. FORM GRINDING — Grinding of tool designed for machining and other operations, in such a way that they are provided with the precise form required for their work, or regrinding them to restore the form after it has been lost as a result of service.
FORMING — Production of shaped part either by means of feeding in a tool ground to shape or form of the part or by what is known as spinning. GRINDING — Finishing operation designed to give to parts already machined the necessary precision of form and accuracy of dimensions by the removal of excess material due to the cutting action of grains of abrasive in a wheel or disc.
Originally used for production of screw and rivet heads in cold working process. HONING — Process whereby a mirror finish is given to important bearing surfaces by using hones or abrasive tools that normally employ both rotary and longitudinal motion. Bonding results from interlocking of the atoms of each piece with some additional interlocking introduced by diffusion.
HYDROJET — A manufacturing process in which a material is cut by a high pressure jet of water often containing an abrasive material to enhance cutting action. LAPPING — Finishing process following grinding, and designed to produce an exceptionally high degree of surface finish as well as a perfectly true surface accurate to size within extremely close limits, by using very fine abrasives.
MAAG PROCESS — The process combines precision grinding of the flanks of the gear teeth with a generating action which ensures that a correct involute form will be maintained, or restored if distortion has taken place as a result of hardening and heat treatment. A millwright is a craftsman in the true sense of the word. Peening introduces compressive stresses on weld surfaces that tend to counteract unwanted tensile stresses.
PICKLING — Process of cleaning that is removing oxide film from castings by dipping them into an acid bath prior to plating, painting or further cold working. Processes 61 PIERCING — Producing holes in a blank by driving a punching tool into the mass of the metal, while at the same time forcing the displaced material into the particular form required by the part, this is known as deep piercing.
PINNING — Scratching of the work surface during a filing operation caused by small particles of metal getting wedged in front of the teeth of the file. PLANING — Producing flat or plane surface on a moving or other part by removing metal from them by means of a cutting tool used in a planing machine.
PLATING — The process of depositing a layer of one metal on another, often done electrically, for the purpose of corrosion protection, appearance, improved electrical conductivity, and other engineering requirements.
The hole material is scrapped. It is a shearing operation carried out in a press. Also refers to the refining of the grain of a coarse grained metal or alloy. It may be either a hot or cold working process. Processes 63 SEASONING — Process by which the internal stresses existing in a piece of material which have been subjected to sudden changes of temperature, as in casting or hardening or have been acted upon by heavy forces in some machining operations are removed.
SERRATING — Method of forming by the use of a knurling tool a series of straight serrations on the outer surface of a part, and parallel with it along the axis of a part. SINTERING — The process of fusing compacted material such as metal powders into a solid or porous piece by applying heat sufficient to bond, but not melt, the particles. SLOTTING — Machine tool operation designed for finishing slots or other enclosed parts not capable of being machined by normal planing or shaping machine.
SMELTING — The process of heating ores to a high temperature in the presence of a reducing agent such as carbon coke and of a fluxing agent to remove the gangue. SPOT WELDING — Method of uniting sheet material by a series of localized welds, produced by overlapping the edges of two sheets of metal and fusing them together between copper electrode tips at suitably spaced intervals, by means of a heavy electrical current.
It is a form of resistance welding. TEMPER ROLLING — Process used in the production of tin -plate, in which the annealed coils or strips are subjected to a small amount of cold reduction in a four high mill in order to increase the stiffness of the dead soft material without unduly reducing its ductility.
THREAD MILLING — Operation of producing threads, both external and internal, by means of thread milling cutters, either single or multi-ribbed, according to the type of thread required and the design of the thread milling machine employed.
TUMBLING — Process of cleaning, polishing, or crushing in which the articles to be treated are mixed with balls, pieces of hard material or abrasive and rotated in a more or less horizontal container. TURNING — Process of reducing the diameter of materials held in a lathe and the general name given to the process whereby material which is turned by means of a driven spindle to which it is attached, is brought into contact with a stationary tool having cutting edges.
May be done manually or by machine. WELDING — Joining of metals by the application of heat, without the use of solder or any other metal or alloy having a lower melting point than the metals being joined. BAND SAW — A narrow endless strip of saw blading running over and driven by pulleys, as a belt used for cutting wood or metal to intricate shapes. It is a group of electric cells connected together. In one type, the spindle only rotates and in another type the spindle rotates and also has a horizontal movement.
The chief feature is the provision of special hand operated rests. The machine comprises a fast and a loose head stock, and a base plate upon which the bed is mounted. The fuel is ignited by the heat of compression only.
In this, the work is fixed to the table which reciprocates under the tool, the tool moving across the table for the purpose of obtaining the feed. This enables two face mills or two horizontal cutters, to work simultaneously on opposite sides of the workpiece. This permits several drilling operations to be made by moving the workpiece from spindle to spindle in a planned sequence. This helps protect the gauge. Grinding excess material off parts previously machined by other methods; forming parts from blanks; parting off lengths of material from rods, bars, billets and so on.
The table and spindle are movable with built in measuring devices. Used for spacing and producing precision holes in tools, dies, and small lot production where extreme accuracy is required. It is a strong, heavily built and a rather slow-moving machine, and the standard range varies from tons per sq.
The lever consists of a rigid arm or bar pivoted or bearing on a point called the fulcrum and has a weight arm and a power arm. LINCOLN MILLER — One of the manufacturing type milling machines, all of which are characterized by the fixed table height with vertical adjustment of the spindle, in contrast with the column and knee type in which the work table is vertically adjustable. The tool to be ground is secured in a chuck having a range of adjustments such that any desired angle can be ground.
MACHINE TOOL — Type of power driven machine for cutting metal as employed in machine shops, the term being usually restricted to those which use the tool that produces waste material in the form of chips or cuttings. Typical machine tools are lathes, planers, shapers, slotters, borers, drills, broaches, millers and saws. The machine comprises a small punch moving up and down at high speed, and so taking a considerable number of small nibbles or cuts. It comprises a bed, a travelling worktable on which the parts to be planed are carried, standards, a cross slide, tool box and gearing.
PUMP — Mechanical device in which a fluid, gas or liquid, is lifted or forced against an external pressure, main types are reciprocating or piston pumps, centrifugal pumps and rotary displacement pumps. It may be of the crank or eccentric variety; the frame of the C or double sided type. In this the drill spindle could be moved to the positions required instead of moving the work for each hole to be drilled.
RAM pump — Hydraulic ram, also termed a water ram, by which water is raised by its own momentum from a lower to a higher level. RELAY — An electromagnetic switch which utilizes variation in the strength of an electric circuit to effect the operation of another circuit. Excessive pressure opens the valve and releases some of the gas or liquid. May be classified according to the method of operation hydraulic, pneumatic, or steam and the manner in which the rivet head is formed.
This may be a vane, geared rotor, centrifugal or turbine type depending on the particular application and the volume of air or gas or the pressure required.
Cams control the movement of the cutting tools, attachments and stock feeding devices to complete workpieces automatically at high production rates.
In this the ram which carries the tool reciprocates while the worktable which carries the workpiece moves perpendicular to the ram movement. It comprises a fixed blade and a shearing tool or blade. There are two types—horizontal and vertical. It turns on when a certain voltage is applied to the gate, and it turns off when the current flowing between the other two terminals stops or reverses. The main difference between them is that the turret saddle has longitudinal movement on the guides of the bed.
Provided with a swivel table and headstock and a wheel head that can be rotated on its base. APRON — The function of a lathe apron is to carry the mechanism for sliding and surfacing motions and screw cutting. BED — One of the principal parts of a machine tool having accurately machined ways or bearing surfaces for supporting and aligning other movable parts of the machine. BELT SHIFTER — A flat hardwood strip of suitable length having shifter fingers attached at one end and used to shift a belt from one pulley to another or to replace a belt which has run off a pulley on an overhead drive shaft.
The large crank gear of a shaper is often called a bull wheel. CAP SCREW — A finished screw, used for fastening two pieces together by passing the screw through a clearance hole in one part and screwing it into a tapped hole in the other.
Heads may be hexagon, round, flat, fillister or socket type. The carriage carries the cutting tool and moves along the ways of the lathe.
It contains the saddle, compound slide, and apron. Change gears on a lathe make it possible to cut threads of different pitches and obtain different feeds per revolution. On milling machines they are used to obtain different leads when milling spirals and helices. A clapper block is hinged into the clapper box to permit the cutting tool to swing upward on the return stroke. COLLET — Means of gripping a bar to give quicker chucking, particularly in capstan work for rapid and accurate setting.
The lower part or base is graduated in degrees and can be swivelled to any angle for turning short tapers and angles. The upper slide carries the tool post and tool holder. Also the exact or precise center of an object. The die head consists of a cylindrical body with a shank to enable it to be clamped in the turret. Fans, Pumps, and Compressors 9. Instruments and Controls Refrigeration, Cryogenics, and Optics Applied Mechanics Summary Solve any mechanical engineering problem quickly and easily with this updated edition of the world's leading engineering handbookThis thoroughly revised, industry-standard resource provides you with all the information you need to solve engineering problems on the job.
Now celebrating its th anniversary, Mark's Standard Handbook for Mechanical Engineers, 12th Edition, offers up-to-date, accurate data and calculations along with clear and concise explanations of theory and applications. First published in , the handbook has become the go-to reference for engineering students and professionals.
You will get coverage of everything from mechanics of solids and fluids, heat, fuels and furnaces to power generation, materials handling, transportation, and manufacturing processes. All-new sections explain micro and nano engineering, robotic vision, alternative energy production, biological materials, biomechanics, composite materials, and much more.
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