This revised edition of the book “MANUAL OF MECHANICAL ENGINEERING TERMS” is expected to be a source of information for students, teachers and practicing engineers in the field of mechanical engineering. This handbook has been prepared to meet the need for a current authoritative, yet concise compilation of key terms associated with the broad field of Mechanical Engineering.
This page
ADDENDUM – The portion of a gear tooth that extends from the stub line outward. ANGLE OF THREAD – The included angle between the sides that form the groove of the thread.
CHAPTERCHAPTER
ALLOWANCE - An intentional or desired difference between the maximum limits of paired parts to provide a particular class of fit. ANGLE – The amount of opening or divergence between two straight lines that meet at the apex or intersect.
GENERAL
FLANK – The straight part of the thread connecting the crest to the root. SPIRE ANGLE OF A THREAD - The angle made by the spiral of the thread to the line of the pitch diameter with a line at right angles to the axis.
MATERIALS
COMBINED CARBON - The portion of the total carbon in steel or cast iron that is present as FREE CARBON. FREE CARBON - The portion of the total carbon in steel or cast iron that is present in elemental form as graphite or tempered carbon.
MATERIAL PROPERTIES
MANUFACTURE – The relative ease of machining related to the hardness of the material to be cut. LUBRICITY – The ability of the lubricant to adhere to the surface under heavy load conditions.
PROCESSES
CALENDAR – A process of rolling the product into slabs to achieve the desired surface finish and thickness. CLIMBING MILLING – Milling process in which the workpiece is fed in the same direction as the path of the teeth on the cutter, below the arbor. DEFORMATION – Change of shape due to the plastic behavior of a metal under stress.
FLAT WELDING – Method of electric resistance welding of sections of material by forming an electric arc between the edges of the pieces to be joined and then pressing together with light pressure the melted edges. THERMIT WELDING – Method of joining iron or steel parts by surrounding the joint with thermite mixture at a sufficiently high temperature to fuse the adjacent surfaces of the parts together.
MACHINES AND DEVICES
DRILLING MACHINE (vertical) – Machine used for drilling, the spindle is vertical, very similar to a radial drill. MULTIPLE SPINDLE DRILLING MACHINE – Machine used to drill a large number of holes in one operation, built purely for repetitive work. PLANER - Machine for removing material from flat surfaces by means of cutting tools fixed in the machine.
SAW MACHINE - A machine tool for cutting metal using a cutting band or disc with cutting teeth. SENSITIVE DRILLING MACHINE - A type of machine that uses hand pressure sensitive drills.
MACHINE COMPONENTS AND ATTACHMENTS
SLOT – A recessed or undercut slot made with a special T shaped cutter in the tables of machine tools to receive the square head of a T bolt for
TUMBLER GEARS - Two gears that act as idler gears between the spindle gear and the fixed stud gear on a lathe gear train. Used to reverse the direction of rotation of the spindle for threading or the feed bar for turning.
BOLT – An externally threaded fastener bent in the shape of the letter U and with both ends threaded
CLAMP – A flat or square piece of metal bent or formed into the shape of the letter U and used for clamping workpieces on a machine table
- BLOCK – Block of metal having a shaped groove cut in its top surface in which can rest a circular shaft
- SUPPORT – Steady in the form of a V, to support the work near the cutting tool
- WAYS – The top part of the bed of a lathe, planer or other machine bed which acts as a bearing surface for aligning and guiding the moving
ABOUTSLEDGE - The large hammer used by the blacksmith's friend, rotates with the smaller blacksmith's hammer. The term angle cutter covers three types of cutters, the single or half-angle, the double-angle, and the equal or combination angle. BELL CENTER PUNCH - Device used for quickly locating and marking the center of the flat end of a cylindrical work piece, preparatory to heavier center punching, center drilling, turning, etc.
BLANKING AND CUPPING TOOL – Tool used to cut a blank and form a cup from sheet or strip metal with a press on the press.
TOOLS AND CUTTERS
DRILL DRILL – A tool for making round holes in metal and other solid materials. INDENTER – a tool used to form an indentation, i.e. small dents on the surface of the product. KRIPPING TOOL - A tool for cutting a knurling or diamond-shaped impression on the surface of a component.
NECK PICKING TOOL - A tool designed and used to reduce the diameter of a component and thereby shape the neck. TRIM NUT – a tool for removing excess material from the edge of the product.
INSTRUMENTS AND GAUGES
DEPTH GAUGE – Gauge used to measure the distance between two surfaces, to find or check the depth of a countersunk hole, a recess, etc. GAUGE CUTTER – Gauge equipped with a dial or dial to measure or compare the thickness of sheet metal plates. DRILL GRIND GAUGE – A tool for checking the angle and length of the cutting lips of a twist drill while it is being sharpened.
LIMIT GAUGE – A gauge that represents a limiting (maximum and minimum) size within which the work will be acceptable. STOP GAUGE – A gauge on which the outer measuring surfaces are designed to test the specified dimensions of holes.
CASTING
CAST IN MOLD – is the mold whose lower half is made in the sand of the foundry floor. BLIND RISERS – An internal riser that does not reach the outside of the mold. CORE SHIFT – Defect resulting from movement of the core from its correct position in the mold cavity.
PUSHUP - An indentation on the casting surface due to displacement (expansion) of sand in the mold. SPRUE - The vertical part of the entry system where the molten metal first enters the mold.
WELDING
JOINT – A joint between two members located approximately at right- angles to each other in the form of a T
TWIN CARBON ARC WELDING – Process that produces coalescence of metals by heating them with an electric arc between two carbon electrodes. ALLOY OF METAL – The addition of different ratios of other elements to a base metal to produce an alloy with specific properties. ANODIC TREATMENT – Formation of a protective oxide layer on the surface of aluminum and its alloys by electrolytic action, to resist corrosion.
Annealing is used to improve machinability and to remove stress from welds, forgings and castings. It is also used to remove stresses caused by cold working and to improve and homogenize the microscopic internal structures of metals.
HEAT AND SURFACE TREATMENTS
CALORISING – Anti-corrosion process for ferrous metals in which an aluminum film is formed on the surface of the metal. PRECIPITATION HARDENING – A process of hardening an alloy by heat treatment in which a component precipitates from a supersaturated material. SHERADIZING – Heat treatment process using zinc dust to produce a rust resistant surface on ferrous metals.
SILICONIZING – The process in which iron and steel parts are impregnated with silicon to improve the surface's resistance to corrosion, heat and wear. CAME PROFILE - The cam surface profile that sets the desired movement of the follower.
MECHANICS OF MACHINES
ANGULAR VELOCITY OF PRECISION – The rate of change in the direction of the plane of rotation of a rotating disc. BEVEL GEARING – Gear arrangement in which the shafts of the shafts connected by gears cross each other. DEDENDUM – The radial distance from the pitch circle to the bottom of the tooth space.
RING SURFACES – The cylindrical surfaces of the equivalent rolling rings for a pair of mating gears. PRECESSIONAL MOTION - Change in the direction of the plane of rotation of a rotating disk.
MATERIAL HANDLING
AUTOMATIC GRAB - A crane grab in which the load is gripped and lowered without manual assistance. BALANCED LUFF - A lifting mechanism in which the moment due to the weight of the arm is in balance with the moment caused by the counterweight. PLAIN LYING ROPE - A rope in which the direction of twisting of the wires is opposite to the direction of the rope in the rope.
STABILITY OF A CRANE – The relationship between righting and tilting moments taken about a tilting axis. CANTILEVER WALL CRANE – Crane designed to run over rails attached to a side wall of the building.
HAND CRANK – Unit directly linked to the load brake and requiring a constant effort in order to lower the load which descends
TRAVELING BREAK CRANE – A crane with a rigid four-legged gantry that is laid over a track laid alongside the work area, on top of the gantry is a rotating part with a jib, a movable counterweight, lifting and pushing units .
HAND CRANK – An arrangement to effect lowering of load at a speed exceeding that of hoisting and finds application where this mode
BODY WEIGHT – The force that the body exerts on the support due to the force of gravity. WINCH – Equipment used for hauling, hauling, or lifting, eg, rope and chain winches, stationary winches, mobile winches. ANTI-CORROSION ADDITIVES – Chemical compounds added to lubricating oil to reduce or prevent the chemical reaction of acids (formed by oxidation of the oil) which destroy certain bearing materials, such as lead in copper bearings, used for crankshafts and engine connecting rods.
API HEAVY TYPE OIL - An engine oil that has the oxidation stability, corrosion prevention and detergent dispersal properties necessary to make it generally suitable for use in high speed diesel and gasoline engines under heavy duty conditions. API PREMIUM TYPE OIL - An engine oil with the oxidation stability and bearing corrosion prevention properties necessary to make it generally suitable for use in internal combustion engines where operating conditions are more severe than normal.
FRICTION, LUBRICATION AND BEARINGS
BATH LUBRICATION – Lubrication system in which the bearing contains a space filled with oil, which is in contact with a portion of the journal. BYPASS FILTER – An oil filter that continuously filters only a portion of the oil flowing through the engine or machine. LAWS OF FRICTION – The force of friction is (1) directly proportional to the pressure between the surfaces in contact, (2) independent of the extent of the surfaces in contact and (3) independent of the velocity of sliding.
OIL RESERVOIR – The space at the bottom of the oil separator where oil is accumulated before returning to the pump. MAIN BEARING – In the engine, the main bearing has thrust surfaces which prevent excessive end movement of the crankshaft.
THERMODYNAMICS AND HEAT TRANSFER
BOYLE'S LAW – The absolute pressure of a gas varies inversely as the volume if the temperature remains constant. CALORIES – The heat per unit weight, one gram, required to raise the temperature of water by one degree Celsius. JOULE'S LAW OF INTERNAL ENERGY – The internal energy of a given amount of gas depends only on the temperature of the gas.
LATENT HEAT – The amount of heat required to change the state or condition under which a substance exists without changing its temperature. LATENT HEAT (internal) – The amount of heat the water will absorb (latent heat minus heat equivalent of work of evaporation), at the boiling point without a change in temperature.
