Page 325 - Mechanical Engineer's Data Handbook

GLOSSARY OF TERMS 313

butt welding The welding together of abutting mem- centre of pressure The point on a submerged surface
bers lying in the same plane. at which the resultant pressure may be taken to act.
centrifugal casting A casting made by pouring mol-
ten material into a rotating mould. This improves the
cam A sliding mechanical device used to convert quality of the casting.
rotary to linear (usually) motion, and vice versa. centrifugal compressor A machine similar to the
capacitaoce The ‘charge’ on a conducting body centrifugal pump used for increasing the pressure of
divided by its ‘potential’. Unit the ‘farad’. gases such as air. It may have several stages.
capacitor An electrical component having centrifugal force A body constrained to move in a
capacitance usually consisting of two conducting curved path reacts with a force (centrifugal force)
surfaces of large area separated by a very thin (usually) directed away from the centre of curvature. It is equal
dielectric. and opposite to the force deviating the body from a
carbide tools High-speed machine tools of tungsten, straight line called the ‘centripetal force’. Both are
titanium or tantalum carbide, or combinations of equal to the mass multiplied by the ‘centripetal
these in a matrix of cobalt or nickel. acceleration’.
carbon steel Steel containing carbon up to about 2% centrifugal pump A pump, usually for liquids, which
and only residual quantities of other elements, except has a rotating ‘impeller’ which increases the pressure
for small amounts of silicon and manganese. and kinetic energy of the fluid.
carburizing Introducing carbon into solid ferrous Centripetal force See ‘centrifugal force’.
alloys by heating in the presence of a carbonaceous centroid The centre of gravity of a lamina. Centre of
material. area.
Carnot cycle An ideal heat engine cycle having the ceramics Non-organic, non-metallic materials of
maximum thermal efficiency, called the ‘Carnot effi- brittle nature, e.g. alumina, carbides.
ciency’. cermet A body of ceramic particles bonded with a
case hardening The production of a hard surface on metal.
steel by heating in a carbonaceous medium to increase chain drive A device consisting of an endless chain
the carbon content, and then quenching. (usually a ‘roller chain’) connecting two wheels
casting An object at or near-finished shape obtained (sprockets) on parallel shafts.
by the solidification of a molten substance in a ‘mould’. chamfer A corner bevelled to eliminate a sharp edge.
The name of the process. charge A quantity of unbalanced electricity in a
cast iron Iron containing carbon suitable for casting, body, i.e. an excess or deficiency of electrons.
e.g. grey, white, malleable, nodular. Charles’ law States that for a ‘perfect gas’ at constant
cavitation The formation and sudden collapse of pressure the volume increases by 1/273 of its volume at
bubbles in a liquid due to local reduction in pressure. 0 “C for each degree Celsius rise in temperature.
Cavitation erosion may be caused on local metal chip A piece of metal removed by a cutting tool or
surfaces. abrasive.
centre drilling Drilling of a conical hole in the end of chip breaker A groove in a cutting tool used to break
a workpiece to support it while being rotated. A ‘centre continuous chips for safety and handling reasons.
drill’ is used. chuck A device for holding work or tools during
centreless grinding The grinding of cylindrical or machining operations.
conical surfaces on workpieces running in rollers clearance The gap or space between two mating
instead of centres. components.
centre of buoyancy The ‘centroid’ of the immersed closed cycle gas turbine A gas turbine unit in which
portion of a floating body. the working fluid continuously circulates without
centre of gravity (centre of mass) The imaginary replenishment.
point in a body at which the mass may be assumed to clutch A device used to connect or disconnect two
be concentrated. rotating shafts, etc., either while rotating or at rest.
centre of percussion The point on a compound cold working Plastic deformation of metal below the
pendulum whose distance from the centre of oscilla- recrystallization temperature.
tion is the same as the length of a simple pendulum column A vertical member with a compressive load;
with the same periodic time. a strut.