Page 329 - Mechanical Engineer's Data Handbook

GLOSSARY OF TERMS 317

expansion per unit length, area, or volume, per unit integral with a body (e.g. engine cylinder block,
increase in temperature. gearbox, cooler) which increase the cooling area.
explosive forming Shaping metal parts confined in finish The surface condition, quality and appearance
dies using the pressure from an explosive charge. of a metal, etc., surface.
extensometer A sensitive instrument for measuring finish machining The final machining of a component
the change in the length of a stressed body. where the objectives are surface finish and accuracy of
extrusion The conversion of a ‘billet’ of metal into dimension.
lengths of uniform cross-section by forcing it through a fit The clearance or interference between mating
die, usually when heated. parts. Also the term for a range of clearance suggested
by standards such as British Standards.
fitting loss The pressure or head loss incurred by
face mill A rotating milling cutter with cutting edges fittings in a pipe or duct such as valves, bends, branch,
on the face to mill a surface perpendicular to the etc.
cutting axis. flame cutting The cutting of metal plate to a desired
facing Generating a flat surface on a rotating work- shape by melting with an oxygen-gas flame.
piece by traversing a tool perpendicular to the axis of flame hardening Quench hardening where the heat is
rotation. supplied by a flame.
factor of safety The ratio between ultimate (or yield) flange A projecting annular rim around the end of a
stress for a material and the permissible stress. (Ab- cylinder or shaft used for strengthening, fastening or
breviation FS or FOS). locating.
failure The breakdown of a member due to excessive flat-plate theory A study of the stresses and deflection
load. Several ‘theories of failure’ are used. of loaded flat plates. It is assumed that the plate is
fan A device for delivering or exhausting large relatively thin and the deflections small.
quantities of air or other gas at low pressure. It consists flexible coupling A coupling usually joining rotating
basically of a rotating axial or centrifugal impeller shafts to accommodate lateral or angular misalign-
running in a casing. ment.
fatigue Phenomenon leading to the failure of a part flowmeter An instrument for measuring the volumet-
under repeated or fluctuating stress below the tensile ric or mass flow of a fluid.
strength of the material. flow rate The rate of flow of a fluid. Units: cubic
fatigue life The number of cycles of fluctuating stress metres per second (m3 s-’) or kilograms per second
required to produce failure in a fatigue test. (kgs- ’).
fatigue limit (endurance limit) The maximum stress flux Material used in soldering, brazing and welding
below which a material can endure an infinite number to prevent the formation of, dissolve, or facilitate the
of stress fluctuation cycles. This only applies to a removal of, oxides, etc.
specially made specimen with a high degree of surface flywheel A heavy wheel on a shaft used either to
finish. reduce speed fluctuation due to uneven torque, or to
feed The rate of advance of a cutting tool along the store energy for punching, shearing, forming, etc.
surface of the workpiece. force That quantity which produces acceleration in a
fibres In ‘composites’, fine threads of a long length of body measured by the rate of change of momentum.
glass, carbon, metal, etc., used to reinforce a material Unit: newton (N).
(e.g. plastics, metals), known as the ‘matrix’. forging Plastic deformation of metal, usually hot,
filler metal Metal added in soldering, brazing and into the desired shape using a compressive force with
welding processes, usually in the form of a rod or stick. or without dies.
fillet wehl A weld of approximately triangular section form cutter A cutter profile sharpened to produce a
joining two surfaces usually at right angles to one specified form of work.
another in a lap, T or corner joint. four-stroke cycle An engine cycle of 4 strokes (2
film lubrication Lubrication where the shaft is separ- revolutions) consisting of induction, compression,
ated from the bearing by a thin film of lubricant which expansion (power) and exhaust strokes; e.g. in the
is under pressure and supports the load. Otto and Diesel cycles.
fin One of usually a number of thin projections Francis turbine A reaction water turbine in which