CAD - Computer Aided Design or Computer Aided Drafting
CAD-Embedding - CAE software with close coupling associated with a direct embedding within Computer-Aided Design
software. This includes a native GUI within the CAD system.
CAE - Computer Aided Engineering.
Cage - The bearing cage is a device used to separate the rolling elements of a bearing.
Cage Pocket - A section of a bearing cage that retains the ball.
Calibration - When recording or analysing any signal it is necessary to calibrate the system with a known signal.
Caliper - A measuring instrument used to measure the distance between two points or the inside or outside dimensions of
an object.
CAM - Computer-Aided Manufacturing
Cam - A device for converting regular rotary motion to irregular rotary or reciprocating motion.
Cam Follower - That part of the push rod that is in contact with the cam.
Camshaft - The shaft which carries the various cams required for the operation of inlet, exhaust, fuel, and starting-air valves.
Canal - An artificial channel of water used by boats and originally designed for the transportation of goods.
Cantilever Beam - A beam that is held in an encastre at one end whilst the other end is unsupported.
Capacitance - measure of the amount of electric charge stored for a given electric potential.
Carbonaceous Biochemical Oxygen Demand (CBOD) - The amount of oxygen required to oxidize any carbon containing matter
present in a water.
Carbonitriding - Introducing carbon and nitrogen into a solid ferrous alloy by holding above the temperature at which
austenite begins to form during heating.
Carbonizing Flame - An oxyacetylene flame in which there is an excess of acetylene.
Carborundum - More commonly known as Silicon Carbide, used extensively as a grinding compound and in abrasive wheels.
Carburizing - Introducing carbon into a solid ferrous alloy.
Carnot's theorems - No engine can be more efficient than a reversible engine working between the same limits of
temperature. All reversible engines working between the same two limits of temperature have the same efficiency.
Cartridge Brass - A brass made with 75.5% copper and 24.5% zinc.
Cascamite - A waterproof resin based glue.
Case - In a ferrous alloy, the outer portion that has been made harder than the inner portion.
Case Hardening - Hardening a ferrous alloy so that the outer portion, or case, is made substantially harder than the inner
portion, or core.
Cast-In-Place - Concrete that is deposited in liquid form in the place where it is required to harden
Cast Iron - An alloy of iron and carbon (2.5%). Distinguished from steel by large amounts of graphite.
Castigated Nut - A nut with grooves cut entirely across the top face.
Casting - A generic term referring to a process where a fluid material is made to flow into a shaped mold cavity where it
solidifies.
Catenary - A chain suspended from two points forms this curve.
Catalytic Cracking (aka Cat Cracking) - The process of breaking up heavier hydrocarbon molecules into lighter hydrocarbon
fractions by using heat and catalysts.
Cation - Ion with a positive charge
Cavitation - A condition which can occur in liquid handling machinery where a system pressure decrease in the suction line
and pump inlet lowers fluid pressure and vaporization occurs.
CBOD - Carbonaceous biochemical oxygen demand
CCTV - Closed circuit television
CD - Abbreviation for drag coefficient, a dimensionless value that allows the comparison of drag incurred by different sized
and different shaped bodies.
Cedar - A durable wood used in ancient buildings. Easy to work and strongly scented.
Cementite - A compound of iron and carbon.
Center of Gravity - The point at which the weight of a body may be considered as concentrated so that if supported at this
point the body would remain in equilibrium in any position. The center of gravity is at the same location as the center of mass.
Center of Mass - The point in a body or system of bodies at which the mass may be considered as concentrated. The center
of mass is at the same location as center of gravity.
Centigrade Heat Unit - The amount of heat necessary to raise one pound weight of water through 1° C.
centipoise - One hundredth of a poise, the CGS derived unit of dynamic viscosity of a fluid.
Centistoke - A cgs unit of kinematic viscosity.
Centre Drill - A combined countersink and drill used to prepare work for mounting centres.
Centre of Mass - The balance point of an object. The location in an object that has the same translational motion as the
object if it were shrunk to a point.
Centre Punch - A pointed hand tool made of hardened steel and shaped somewhat like a pencil.
Centres - Headstock and tailstock centres used to retain and centre the workpiece in a lathe.
Centrifugal Force - A fictitious force arising in a rotating reference system.
Centripetal - An adjective meaning 'centre-fleeing.'
Ceramic - Inorganic non-metallic material which is formed by the action of heat.
Cermet - A composite material consisting of a combination of ceramic and metallic materials.
Cetane Index - A calculated value, derived from fuel density and volatility, giving a reasonably close approximation to cetane
number.
Cetane Number - A percentage indicating the ignition quality of diesel fuels.
CFC - Chlorofluorocarbon
CFD - Computational Fluid Dynamics. CFD is a computer-based mathematical modeling tool that incorporates the solution of
the fundamental equations of fluid flow, the Navier-Stokes equations, and other allied equations.
CFM - Cubic foot per minute, a British imperial unit of flow rate.
CFR - Code of Federal Regulations
ch - Metric horsepower.
Chain Drive - Power transmission by means of an endless chain running around chain wheels or sprocket wheels.
Chainring Nut Spanner - A special bicycle tool used to loosen the slotted nuts that fasten a chainring to a crankarm.
Chamfer - Beveled corner.
Change Order - A client's written order to a contractor, issued after execution of the construction contract, which authorizes
a change in the construction work and contract time and/or amount
Channel - A frequency interval or frequency band assigned for communications.
Charpy Test - An impact test in which a V-notched, keyhole-notched, or U-notched specimen, supported at both ends
horizontally, is struck behind the notch by a striker mounted at the lower end of a pendulum.
Chasing Threads - The process of cutting threads in a lathe or screw machine.
Chatter - The vibrations caused between the work and the cutting tool which leave distinctive tool marks on the finished
surface that are objectionable.
Check Valve - A valve that permits the passage of a liquid or gas in one direction only. It stops, or checks, reverse flow.
Chemical Oxygen Demand (COD) - The amount of oxygen required to oxidize any organic matter in the water using harsh
chemical conditions.
Chemical Set Cement - A cement that sets through reaction or precipitation.
Chestnut - Very durable and much like oak. Comparitavely easy to work and does not shrink much when drying.
Cheval Vapeur - Metric horsepower.
Chipping - The process of cutting metal with a cold chisel and hammer.
Chipping Hammer - A hammer used to remove the slag from weld seams.
Chlorofluorocarbons - Synthetic organic compounds used for refrigerants, aerosol propellants (prohibited in the U.S.), and
blowing agents in plastic foams.
Chu - Abbreviation of centigrade heat unit.
Chuck - A device on a machine tool to hold the workpiece or a cutting tool.
Cinnabar - Mercuric Sulphide, the ore of mercury. Occuring as red crystals.
Circlip - A clip that fits in a groove on a shaft and locates the shaft axially in one direction.
Circulating Fluidized-Bed (CFB) Boilers - Used with a variety of fuels, particularly successful at burning those of poor quality.
When the flow of air reaches a certain velocity, it causes the solid particles to lift (or fluidize) and combustion occurs in this
fluidized zone.
CL - Abbreviation for lift coefficient, a dimensionless value that allows the comparison of lift incurred by different sized and
different shaped bodies.
Clamp - A fastening device which secures something within its jaws without constant human pressure.
Clamping Force - The compressive force which a fastener exerts on the joint.
Claw Hammer - A hammer with a forked end on the head which is used for removing nails.
Cleanroom — A confined area in which the humidity, temperature and particulate matter are precisely controlled
Clearance - The distance or angle by which one object or surface clears another.
Cleavage - Transcrystalline fracture along specific crystallographic planes.
Climb Milling - A method of milling in which the work table moves in the same direction as the direction of rotation of the
milling centre.
Club Hammer - A hammer with a short handle but a large, heavy head.
COD - Chemical Oxygen Demand
Coefficient of Friction - A dimensionless scalar value which describes the ratio of the force of friction between two bodies and
the force pressing them together.
Cog - A tooth in the rim of a wheel or a gear tooth in a gear wheel.
Cogeneration - The use of a single plant to simultaneously produce power and heat or steam.
Coke - A high carbon content solid residue from an oil refinery process, which can be used as a boiler fuel to produce steam
and electric power.
Coking - Processes for thermally converting and upgrading heavy residual oil into lighter products and by-product petroleum
coke.
Cold Drawing - This is a process for finishing a hot rolled rod or bar at room temperature by pulling it through the hole of a
die of the same shape but smaller in size.
Cold Junction - The reference junction of a thermocouple which is kept at a constant temperature.
Cold Rolling - The cold working of hot rolled material by passing it between power driven rolls.
Cold Treatment - A heat treat process which converts unstable retained Austenite into stable untempered Martensite.
Cold Working - The plastic deformation of a metal at a temperature below that at which it re-crystallizes.
Collet - A precision work holding chuck which centres finished round stock automatically when tightened.
Colour Temperature - The colour of a piece of steel may be used as a guide to it's temperature. These are particulalrly useful
when hardening or tempering steel.
Columbium - A name sometimes given to Niobium, a platinum-gray, ductile metal with brilliant luster that is used in alloys,
especially stainless steels.
Combination Spanner - A flat wrench with a hex ring at one end and an open end at the other.
Combination Square - A drafting and layout tool combining a square, level, protractor, and centre head.
Combined-Cycle Engine - Engine concepts using some combination of air-breathing and rocket components which are
integrated into a single propulsion system.
Combustion Chamber - The space above the piston in which the fuel-air mixture starts to burn in an internal combustion
engine.
Compliance - The displacement caused by a unit force applied to a spring or structural component. It is the reciprocal of
stiffness (Units m/N).
Composite - A material brought about by combining materials differing in composition or form on a macroscale for the
purpose of obtaining specific characteristics and properties.
Compressibility - The change in volume of a unit volume of a fluid when subjected to a unit change of pressure.
Compression Ignition - Ignition of a fuel charge by the heat of the air in a cylinder, generated by compression of the air, as in
the diesel engine.
Compression Ratio - In an engine, the ratio of the cylinder volume at BDC (Bottom Dead Centre) to cylinder volume at TDC
(Top Dead Centre).
Compressive Strength - For metals, the compressive strength is the same as the tensile yield strength.
Compressive Stress - Stress on the cross-sectional area of a body normal to the compression force acting on the body
Computer Aided Design - Usually applied to that part of CAE which has to do with the drawing or physical layout steps of
engineering design.
Computer Aided Engineering - A technique for using computers to help with all phases of engineering design work.
Concentrated Force - A force considered to act along a single line in space.
Concentric - Having a common centre.
Conceptual Design - The first phase of design, in which drawings are the dominant tool and product.
Condensation - the process of changing a vapor into liquid by the extraction of heat.
Conduction (electrical) - The transfer of electrical current through a solid or liquid.
Conduction (thermal) - The transfer of heat between two solid materials that are physically touching each other.
Conductivity (electrical) - A material's ability to conduct an electric current.
Conductivity (thermal) - The property of a material that indicates its ability to conduct heat.
Cone Pulley - A one-piece stepped pulley having two or more diameters.
Conjugate Tooth Pairs - Two gear teeth are conjugate if they produce uniform motion as they roll together.
Connecting Rod - The part in an internal combustion engine that connects the piston to the crankshaft.
Connection - A connection restrains degrees of freedom of one member with respect to another.
Conrod - Abbreviation of connecting rod, the part in an internal combustion engine that connects the piston to the crankshaft.
Constrained-Layer Damper - A layer of damping material between the structure′s surface and an additional elastic layer.
Contact Ratio - The contact ratio is the average numberof pairs of teeth in contact between two gears.
Contaminant - Any foreign or unwanted substance that can have a negative effect on system operation, life or reliability.
Continuity Equation - An equation which states that a fluid flowing through a pipe flows at a rate which is inversely
proportional to the cross-sectional area of the pipe.
Continuous System - A continuous system is one that is considered to have an infinite number of possible independent
displacements.
Continuously Variable Transmission - A drive system where a belt running on pairs of cones allows the ratio between the
input and output shafts to be varied continuously between the maximum and minimum ratios.
Coolant - A fluid used to remove heat.
Cooling Fan - The size, specification and location of a cooling fan will depend upon the amount of heat that has to be
dissipated from the object that has to be cooled.
Cope - The top half of a horizontally parted mould.
Copper Faced Hammer - A hammer with a round head made of copper or brass.
Corrosion - Deteriorative loss of a metal as a result of dissolution environmental reactions.
Coulomb Damping - Coulomb damping is the dissipation of energy that occurs when a particle in a vibrating system is
resisted by a force whose magnitude is constant independent of displacement and velocity, and whose direction is opposite
to the direction of the velocity of the particle.
Counter Weight - A weight added to a body so as to reduce a calculated unbalance at a desired place.
Countersink - To counter bore a hole such that the head of a screw may sit flush with the surface.
Couple - Two equal forces acting on a body in opposite directions and located at a specific distance apart produce a turning
effect on the body.
Coupling - Mechanical fixture for joining two shafts.
Covalent Bond - A bond in which electrons are shared approximately equally by two atoms.
CP - Abbreviation for pressure coefficient, a dimensionless value which acts as a means of indicating the local pressure at
some point of interest around a body, and which is independent of velocity.
cP - An abbreviation of centipoise, one hundredth of a poise. The CGS derived unit of dynamic viscosity of a fluid.
Crack - A fracture type discontinuity characterized by a sharp tip and high ratio of length and width to opening displacement.
Cracking - The production of lighter oils by breaking down heavy oil molecules. This process increases the yield of gasoline
from crude oil.
Crank - That part of the crankshaft, which is in the form of a crank and crank pin.
Crankcase - The middle part of the engine structure surrounding the working parts.
Crankcase Emissions - Pollutants allowed to escape into the atmosphere from the crankcase of an internal combustion
engine.
Crankshaft - That part of the engine which transmits the reciprocating motion of the pistons to the driven unit in the form of
rotary motion.
Creep - The time-dependent permanent deformation that occurs under stress.
Critical Cooling Rate - The minimum rate of continuous cooling just sufficient to prevent undesired transformations.
Critical Damping - The smallest value of damping required for a displaced system to return to its equilibrium position without
overshooting or oscillating about that position.
Critical Point - The temperature or pressure at which a change in crystal structure, phase or physical properties occurs.
Critical Resolved Shear Stress - The shear stress, resolved within a slip plane and direction, which is required to initiate slip.
Critical Speeds - Any rotating shaft will have lateral (or flexural) and torsional natural frequencies. If the shaft is subjected to
a force at any of these frequencies, the amplitude of vibration will be particularly large.
Cross Section - A view showing an internal structure as it would be revealed by cutting through the piece in any plane.
Cruise Control - Control system used to maintain the vehicle speed without the invention of a driver.
C-Spanner - A spanner whose end is shaped like a C, used to loosen the lockring on a bottom bracket of a bicycle.
cSt - Abbreviation of Centistoke, a unit of kinematic viscosity.
Cubic Foot per Minute - British imperial unit of flow rate.
Cubic Foot per Second - British imperial unit of flow rate.
cufm - Cubic foot per minute, a British imperial unit of flow rate.
Cure - To irreversibly polymerize a thermosetting plastic by subjecting it to a time-temperature profile.
Curie Temperature - The temperature above which a ferromagnetic or ferrimagnetic material becomes paramagnetic.
cusec - Abbreviation of cubic foot per second.
Cutting Fluid - A liquid used to cool and lubricate the cutting to improve the work surface finish.
Cutting Tool - A hardened piece of metal that is machined and ground so that it has the shape and cutting edges appropriate
for the operation for which it is to be used.
CVT - Abbreviation of Continuously Variable Transmission.
Cyanoacrylate - More commonly known as Super Glue or Instant Glue.
Cycle Counting - Cycle counting is used to summarize lengthy, irregular load-versus-time histories by providing the number of
times cycles of various amplitudes occur.
CAD-Embedding - CAE software with close coupling associated with a direct embedding within Computer-Aided Design
software. This includes a native GUI within the CAD system.
CAE - Computer Aided Engineering.
Cage - The bearing cage is a device used to separate the rolling elements of a bearing.
Cage Pocket - A section of a bearing cage that retains the ball.
Calibration - When recording or analysing any signal it is necessary to calibrate the system with a known signal.
Caliper - A measuring instrument used to measure the distance between two points or the inside or outside dimensions of
an object.
CAM - Computer-Aided Manufacturing
Cam - A device for converting regular rotary motion to irregular rotary or reciprocating motion.
Cam Follower - That part of the push rod that is in contact with the cam.
Camshaft - The shaft which carries the various cams required for the operation of inlet, exhaust, fuel, and starting-air valves.
Canal - An artificial channel of water used by boats and originally designed for the transportation of goods.
Cantilever Beam - A beam that is held in an encastre at one end whilst the other end is unsupported.
Capacitance - measure of the amount of electric charge stored for a given electric potential.
Carbonaceous Biochemical Oxygen Demand (CBOD) - The amount of oxygen required to oxidize any carbon containing matter
present in a water.
Carbonitriding - Introducing carbon and nitrogen into a solid ferrous alloy by holding above the temperature at which
austenite begins to form during heating.
Carbonizing Flame - An oxyacetylene flame in which there is an excess of acetylene.
Carborundum - More commonly known as Silicon Carbide, used extensively as a grinding compound and in abrasive wheels.
Carburizing - Introducing carbon into a solid ferrous alloy.
Carnot's theorems - No engine can be more efficient than a reversible engine working between the same limits of
temperature. All reversible engines working between the same two limits of temperature have the same efficiency.
Cartridge Brass - A brass made with 75.5% copper and 24.5% zinc.
Cascamite - A waterproof resin based glue.
Case - In a ferrous alloy, the outer portion that has been made harder than the inner portion.
Case Hardening - Hardening a ferrous alloy so that the outer portion, or case, is made substantially harder than the inner
portion, or core.
Cast-In-Place - Concrete that is deposited in liquid form in the place where it is required to harden
Cast Iron - An alloy of iron and carbon (2.5%). Distinguished from steel by large amounts of graphite.
Castigated Nut - A nut with grooves cut entirely across the top face.
Casting - A generic term referring to a process where a fluid material is made to flow into a shaped mold cavity where it
solidifies.
Catenary - A chain suspended from two points forms this curve.
Catalytic Cracking (aka Cat Cracking) - The process of breaking up heavier hydrocarbon molecules into lighter hydrocarbon
fractions by using heat and catalysts.
Cation - Ion with a positive charge
Cavitation - A condition which can occur in liquid handling machinery where a system pressure decrease in the suction line
and pump inlet lowers fluid pressure and vaporization occurs.
CBOD - Carbonaceous biochemical oxygen demand
CCTV - Closed circuit television
CD - Abbreviation for drag coefficient, a dimensionless value that allows the comparison of drag incurred by different sized
and different shaped bodies.
Cedar - A durable wood used in ancient buildings. Easy to work and strongly scented.
Cementite - A compound of iron and carbon.
Center of Gravity - The point at which the weight of a body may be considered as concentrated so that if supported at this
point the body would remain in equilibrium in any position. The center of gravity is at the same location as the center of mass.
Center of Mass - The point in a body or system of bodies at which the mass may be considered as concentrated. The center
of mass is at the same location as center of gravity.
Centigrade Heat Unit - The amount of heat necessary to raise one pound weight of water through 1° C.
centipoise - One hundredth of a poise, the CGS derived unit of dynamic viscosity of a fluid.
Centistoke - A cgs unit of kinematic viscosity.
Centre Drill - A combined countersink and drill used to prepare work for mounting centres.
Centre of Mass - The balance point of an object. The location in an object that has the same translational motion as the
object if it were shrunk to a point.
Centre Punch - A pointed hand tool made of hardened steel and shaped somewhat like a pencil.
Centres - Headstock and tailstock centres used to retain and centre the workpiece in a lathe.
Centrifugal Force - A fictitious force arising in a rotating reference system.
Centripetal - An adjective meaning 'centre-fleeing.'
Ceramic - Inorganic non-metallic material which is formed by the action of heat.
Cermet - A composite material consisting of a combination of ceramic and metallic materials.
Cetane Index - A calculated value, derived from fuel density and volatility, giving a reasonably close approximation to cetane
number.
Cetane Number - A percentage indicating the ignition quality of diesel fuels.
CFC - Chlorofluorocarbon
CFD - Computational Fluid Dynamics. CFD is a computer-based mathematical modeling tool that incorporates the solution of
the fundamental equations of fluid flow, the Navier-Stokes equations, and other allied equations.
CFM - Cubic foot per minute, a British imperial unit of flow rate.
CFR - Code of Federal Regulations
ch - Metric horsepower.
Chain Drive - Power transmission by means of an endless chain running around chain wheels or sprocket wheels.
Chainring Nut Spanner - A special bicycle tool used to loosen the slotted nuts that fasten a chainring to a crankarm.
Chamfer - Beveled corner.
Change Order - A client's written order to a contractor, issued after execution of the construction contract, which authorizes
a change in the construction work and contract time and/or amount
Channel - A frequency interval or frequency band assigned for communications.
Charpy Test - An impact test in which a V-notched, keyhole-notched, or U-notched specimen, supported at both ends
horizontally, is struck behind the notch by a striker mounted at the lower end of a pendulum.
Chasing Threads - The process of cutting threads in a lathe or screw machine.
Chatter - The vibrations caused between the work and the cutting tool which leave distinctive tool marks on the finished
surface that are objectionable.
Check Valve - A valve that permits the passage of a liquid or gas in one direction only. It stops, or checks, reverse flow.
Chemical Oxygen Demand (COD) - The amount of oxygen required to oxidize any organic matter in the water using harsh
chemical conditions.
Chemical Set Cement - A cement that sets through reaction or precipitation.
Chestnut - Very durable and much like oak. Comparitavely easy to work and does not shrink much when drying.
Cheval Vapeur - Metric horsepower.
Chipping - The process of cutting metal with a cold chisel and hammer.
Chipping Hammer - A hammer used to remove the slag from weld seams.
Chlorofluorocarbons - Synthetic organic compounds used for refrigerants, aerosol propellants (prohibited in the U.S.), and
blowing agents in plastic foams.
Chu - Abbreviation of centigrade heat unit.
Chuck - A device on a machine tool to hold the workpiece or a cutting tool.
Cinnabar - Mercuric Sulphide, the ore of mercury. Occuring as red crystals.
Circlip - A clip that fits in a groove on a shaft and locates the shaft axially in one direction.
Circulating Fluidized-Bed (CFB) Boilers - Used with a variety of fuels, particularly successful at burning those of poor quality.
When the flow of air reaches a certain velocity, it causes the solid particles to lift (or fluidize) and combustion occurs in this
fluidized zone.
CL - Abbreviation for lift coefficient, a dimensionless value that allows the comparison of lift incurred by different sized and
different shaped bodies.
Clamp - A fastening device which secures something within its jaws without constant human pressure.
Clamping Force - The compressive force which a fastener exerts on the joint.
Claw Hammer - A hammer with a forked end on the head which is used for removing nails.
Cleanroom — A confined area in which the humidity, temperature and particulate matter are precisely controlled
Clearance - The distance or angle by which one object or surface clears another.
Cleavage - Transcrystalline fracture along specific crystallographic planes.
Climb Milling - A method of milling in which the work table moves in the same direction as the direction of rotation of the
milling centre.
Club Hammer - A hammer with a short handle but a large, heavy head.
COD - Chemical Oxygen Demand
Coefficient of Friction - A dimensionless scalar value which describes the ratio of the force of friction between two bodies and
the force pressing them together.
Cog - A tooth in the rim of a wheel or a gear tooth in a gear wheel.
Cogeneration - The use of a single plant to simultaneously produce power and heat or steam.
Coke - A high carbon content solid residue from an oil refinery process, which can be used as a boiler fuel to produce steam
and electric power.
Coking - Processes for thermally converting and upgrading heavy residual oil into lighter products and by-product petroleum
coke.
Cold Drawing - This is a process for finishing a hot rolled rod or bar at room temperature by pulling it through the hole of a
die of the same shape but smaller in size.
Cold Junction - The reference junction of a thermocouple which is kept at a constant temperature.
Cold Rolling - The cold working of hot rolled material by passing it between power driven rolls.
Cold Treatment - A heat treat process which converts unstable retained Austenite into stable untempered Martensite.
Cold Working - The plastic deformation of a metal at a temperature below that at which it re-crystallizes.
Collet - A precision work holding chuck which centres finished round stock automatically when tightened.
Colour Temperature - The colour of a piece of steel may be used as a guide to it's temperature. These are particulalrly useful
when hardening or tempering steel.
Columbium - A name sometimes given to Niobium, a platinum-gray, ductile metal with brilliant luster that is used in alloys,
especially stainless steels.
Combination Spanner - A flat wrench with a hex ring at one end and an open end at the other.
Combination Square - A drafting and layout tool combining a square, level, protractor, and centre head.
Combined-Cycle Engine - Engine concepts using some combination of air-breathing and rocket components which are
integrated into a single propulsion system.
Combustion Chamber - The space above the piston in which the fuel-air mixture starts to burn in an internal combustion
engine.
Compliance - The displacement caused by a unit force applied to a spring or structural component. It is the reciprocal of
stiffness (Units m/N).
Composite - A material brought about by combining materials differing in composition or form on a macroscale for the
purpose of obtaining specific characteristics and properties.
Compressibility - The change in volume of a unit volume of a fluid when subjected to a unit change of pressure.
Compression Ignition - Ignition of a fuel charge by the heat of the air in a cylinder, generated by compression of the air, as in
the diesel engine.
Compression Ratio - In an engine, the ratio of the cylinder volume at BDC (Bottom Dead Centre) to cylinder volume at TDC
(Top Dead Centre).
Compressive Strength - For metals, the compressive strength is the same as the tensile yield strength.
Compressive Stress - Stress on the cross-sectional area of a body normal to the compression force acting on the body
Computer Aided Design - Usually applied to that part of CAE which has to do with the drawing or physical layout steps of
engineering design.
Computer Aided Engineering - A technique for using computers to help with all phases of engineering design work.
Concentrated Force - A force considered to act along a single line in space.
Concentric - Having a common centre.
Conceptual Design - The first phase of design, in which drawings are the dominant tool and product.
Condensation - the process of changing a vapor into liquid by the extraction of heat.
Conduction (electrical) - The transfer of electrical current through a solid or liquid.
Conduction (thermal) - The transfer of heat between two solid materials that are physically touching each other.
Conductivity (electrical) - A material's ability to conduct an electric current.
Conductivity (thermal) - The property of a material that indicates its ability to conduct heat.
Cone Pulley - A one-piece stepped pulley having two or more diameters.
Conjugate Tooth Pairs - Two gear teeth are conjugate if they produce uniform motion as they roll together.
Connecting Rod - The part in an internal combustion engine that connects the piston to the crankshaft.
Connection - A connection restrains degrees of freedom of one member with respect to another.
Conrod - Abbreviation of connecting rod, the part in an internal combustion engine that connects the piston to the crankshaft.
Constrained-Layer Damper - A layer of damping material between the structure′s surface and an additional elastic layer.
Contact Ratio - The contact ratio is the average numberof pairs of teeth in contact between two gears.
Contaminant - Any foreign or unwanted substance that can have a negative effect on system operation, life or reliability.
Continuity Equation - An equation which states that a fluid flowing through a pipe flows at a rate which is inversely
proportional to the cross-sectional area of the pipe.
Continuous System - A continuous system is one that is considered to have an infinite number of possible independent
displacements.
Continuously Variable Transmission - A drive system where a belt running on pairs of cones allows the ratio between the
input and output shafts to be varied continuously between the maximum and minimum ratios.
Coolant - A fluid used to remove heat.
Cooling Fan - The size, specification and location of a cooling fan will depend upon the amount of heat that has to be
dissipated from the object that has to be cooled.
Cope - The top half of a horizontally parted mould.
Copper Faced Hammer - A hammer with a round head made of copper or brass.
Corrosion - Deteriorative loss of a metal as a result of dissolution environmental reactions.
Coulomb Damping - Coulomb damping is the dissipation of energy that occurs when a particle in a vibrating system is
resisted by a force whose magnitude is constant independent of displacement and velocity, and whose direction is opposite
to the direction of the velocity of the particle.
Counter Weight - A weight added to a body so as to reduce a calculated unbalance at a desired place.
Countersink - To counter bore a hole such that the head of a screw may sit flush with the surface.
Couple - Two equal forces acting on a body in opposite directions and located at a specific distance apart produce a turning
effect on the body.
Coupling - Mechanical fixture for joining two shafts.
Covalent Bond - A bond in which electrons are shared approximately equally by two atoms.
CP - Abbreviation for pressure coefficient, a dimensionless value which acts as a means of indicating the local pressure at
some point of interest around a body, and which is independent of velocity.
cP - An abbreviation of centipoise, one hundredth of a poise. The CGS derived unit of dynamic viscosity of a fluid.
Crack - A fracture type discontinuity characterized by a sharp tip and high ratio of length and width to opening displacement.
Cracking - The production of lighter oils by breaking down heavy oil molecules. This process increases the yield of gasoline
from crude oil.
Crank - That part of the crankshaft, which is in the form of a crank and crank pin.
Crankcase - The middle part of the engine structure surrounding the working parts.
Crankcase Emissions - Pollutants allowed to escape into the atmosphere from the crankcase of an internal combustion
engine.
Crankshaft - That part of the engine which transmits the reciprocating motion of the pistons to the driven unit in the form of
rotary motion.
Creep - The time-dependent permanent deformation that occurs under stress.
Critical Cooling Rate - The minimum rate of continuous cooling just sufficient to prevent undesired transformations.
Critical Damping - The smallest value of damping required for a displaced system to return to its equilibrium position without
overshooting or oscillating about that position.
Critical Point - The temperature or pressure at which a change in crystal structure, phase or physical properties occurs.
Critical Resolved Shear Stress - The shear stress, resolved within a slip plane and direction, which is required to initiate slip.
Critical Speeds - Any rotating shaft will have lateral (or flexural) and torsional natural frequencies. If the shaft is subjected to
a force at any of these frequencies, the amplitude of vibration will be particularly large.
Cross Section - A view showing an internal structure as it would be revealed by cutting through the piece in any plane.
Cruise Control - Control system used to maintain the vehicle speed without the invention of a driver.
C-Spanner - A spanner whose end is shaped like a C, used to loosen the lockring on a bottom bracket of a bicycle.
cSt - Abbreviation of Centistoke, a unit of kinematic viscosity.
Cubic Foot per Minute - British imperial unit of flow rate.
Cubic Foot per Second - British imperial unit of flow rate.
cufm - Cubic foot per minute, a British imperial unit of flow rate.
Cure - To irreversibly polymerize a thermosetting plastic by subjecting it to a time-temperature profile.
Curie Temperature - The temperature above which a ferromagnetic or ferrimagnetic material becomes paramagnetic.
cusec - Abbreviation of cubic foot per second.
Cutting Fluid - A liquid used to cool and lubricate the cutting to improve the work surface finish.
Cutting Tool - A hardened piece of metal that is machined and ground so that it has the shape and cutting edges appropriate
for the operation for which it is to be used.
CVT - Abbreviation of Continuously Variable Transmission.
Cyanoacrylate - More commonly known as Super Glue or Instant Glue.
Cycle Counting - Cycle counting is used to summarize lengthy, irregular load-versus-time histories by providing the number of
times cycles of various amplitudes occur.
Engineering Glossary, Engineering Dictionary C
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