Machine Design (MD 1) Review Terminology

Comprehensive vocabulary flashcards covering machine design, mechanical components, manufacturing processes, materials science, and mechanics definitions from the lecture reading set.

Tachometer

A device used to measure speed accurately.

Interference of Metal

A condition occurring when a hole is smaller than the shaft, requiring pressure to assemble the parts, resulting in a negative allowance.

Plasticity

The ability of a metal to be deformed considerably without rupture.

Ductility

The property that characterizes a material's ability to undergo permanent deformation or strain without fracture, or to be drawn into a wire.

Kinematics

The science of motion that deals with the motion of bodies without reference to the forces causing them, solvable in terms of scalar or vector algebra.

Babbitt

A metal that assists lubrication or serves as a lubricant in itself.

Dividing Head

A mechanism that performs the indexing operation in a machine tool.

Flywheel

A mechanical device that equalizes the energy exerted and the work done, thereby preventing excessive or sudden changes of speed.

Percentage Reduction of Area

The smallest area at the point of rupture of a tensile specimen divided by the original area.

Linear Impulse

The product of the resultant of all forces acting on a body and the time that the resultant acts.

Poisson's Ratio

The ratio of unit lateral strain (or lateral deformation) to unit longitudinal strain (or longitudinal deformation).

Ultimate Stress

The maximum stress to which a material may be subjected before failure occurs.

Hypoid Gear

A special type of gear similar to a bevel gear.

Three-Moment Equation

An equation used in structural analysis to analyze continuous beams.

Braze Welding

A joining method where a non-ferrous filler metal is melted into grooves or as a fillet onto the mother metal without melting the base metal.

Creep

The phenomenon of continuous stretching under load even if the applied stress is less than the yield point.

Planing

A machining operation wherein the fastened workpiece undergoes reciprocating motion while the tool head remains stationary.

Killed Steel

Steel that has been completely deoxidized during melting, characteristically associated with silicon additions.

Pitch Plane

In a pair of gears, the plane perpendicular to the axial plane and tangent to the pitch surface.

Chordal Thickness

The tooth width of a gear measured along the chord at the pitch circle.

Clearance (Gear Teeth)

The difference between addendum and dedendum, equivalent to the whole depth less the working depth, or the radial distance between the top of a tooth and the bottom of the mating tooth space.

Inertia

The property of matter that causes it to resist any change in its motion or state of rest.

Square Thread

A screw thread profile where the thread width is approximately equal to the thread depth and the space between threads is approximately equal.

Turret Lathe

A lathe equipped with multiple cutting stations for sequential machining operations.

Lead

The distance a helical gear or worm thread advances along its axis in one complete revolution if free to move axially.

Length of Engagement

The axial length of contact between two mating thread parts in a screw and nut assembly.

Offset Bearing

A bearing type also referred to as an eccentrically loaded bearing.

Regular Lay

A wire rope construction where the individual wires and strands are twisted in opposite directions.

Angle of Obliquity

An alternate term for the pressure angle in involute teeth, defined as the angle between the line of action and the line tangent to the pitch circle.

Addendum

The radial distance between the pitch circle and the top land of a gear tooth.

Hunting Tooth

An extra tooth added to a gear to evenly distribute wear across all meshing teeth over multiple rotations.

Lead Angle

The angle made by the helix of a straight thread at the pitch diameter with a plane perpendicular to the axis.

Couple

A pair of equal, opposite, parallel, and non-collinear forces that tend to cause rotational motion in a body.

English Module

The ratio of the pitch diameter in inches to the total number of teeth on a gear.

Linear Momentum

The product of the mass of a body and the velocity of its center of gravity.

Pitch (Gear Teeth)

The distance between similar, equally spaced tooth surfaces measured in a given direction along a designated line.

Scalar

A quantity that is completely specified solely by its magnitude, such as time, volume, and density.

Flexible Disk Coupling

A coupling providing axial flexibility, constructed by alternately bolting steel, leather, fabric, and/or plastic materials between two flanges.

Four-Bar Linkage

A kinematic linkage consisting of two cranks, a stationary member known as the line of centers, and a connecting rod.

Bottom Diameter

The pitch diameter of a roller chain sprocket minus the diameter of the roller chain.

Tolerance

The permissible variation allowed in manufactured or machined dimensions.

Allowance

The intentional difference between the maximum material limits of mating parts, representing minimum clearance or maximum interference.

Fillet Curve

The concave curved portion of a gear tooth profile where it joins the bottom of the tooth space.

Stiffness

The mechanical property of a material characterizing its ability to resist deformation when subjected to stress.

Angle of Thread

The angle included between the sides of a screw thread measured in an axial plane.

Spring

An elastic body designed primarily to deflect under an applied load and recover its shape.

SAE 13XX

The Society of Automotive Engineers standard designation for manganese steel.

SAE 5XXX

The Society of Automotive Engineers standard designation for chromium steel.

Whole Depth

The total radial depth of a tooth space, calculated as the sum of the addendum and dedendum.

Residual Stresses

Internal stresses that remain within a structural member or component independent of external working loads.

Austenite

A phase of steel elements possessing a face-centered cubic (FCC) crystal structure.

Principal Planes

Specific planes within a stressed material where the shearing stress is zero and principal normal stresses act.

Homogeneity

The property of a material wherein its substance and composition are continuously and uniformly distributed throughout its entire mass.

SAE 10XX

The standard designation for plain carbon steel.

Involute

A curve formed by the path of a point on a straight line as it rolls without slipping along a convex base circle, commonly used for gear profiles.

Fit

The acceptable range of tightness or looseness resulting from the specific combination of allowances and tolerances applied to mating parts.

Kinematic Viscosity

The absolute viscosity of a fluid divided by its density, expressed in consistent units.

Full Bearing

A journal bearing whose bearing surface completely surrounds the circumference of the journal.

Backlash

The amount by which the width of a gear tooth space exceeds the thickness of the engaging tooth measured on the pitch circle.

Link

A rigid kinematic member serving to transmit forces or cause and control motion between interconnected machine parts.

Stud Bolt

A fastening rod threaded on both ends with an unthreaded body in the middle, commonly used in construction.

Bulk Modulus

The ratio of hydrostatic stress acting on an elastic substance to the resulting volumetric strain (decrease in volume per unit volume).

Edge Joint

A welded joint produced along the parallel edges of two adjacent plates.

Screw Thread

A ridge of uniform cross section in the form of a helix cut around the circumference of a cylinder advancing axially.

Abrasive

A hard material capable of cutting, grinding, or wearing away substances brought into contact with it.

Compressive Strength

The peculiar strength of a material to withstand crushing or compressive loads without failure.

Bottom Land

The bottom surface of a gear tooth space bounded by the adjacent fillet curves.

Transverse Plane

In gears, the plane perpendicular to the axial plane and to the pitch plane, which coincides with the plane of rotation.

Blanking

The sheet metal shearing operation of cutting out an exterior piece of metal to a desired shape and dimension.

Keyseat

An axially located rectangular groove machined into a shaft or hub to receive a drive key.

Specific Gravity

A dimensionless number indicating how many times heavier a volume of a substance is compared to an equal volume of pure water.

Oscillation

A reciprocating circular motion that traces an arc about a pivot, such as the motion of a pendulum.

Flank (Screw Thread)

The straight thread surface that directly connects the crest and the root.

Cathodic Protection

The application of an external electrical direct current to a corrosion cell to suppress corrosion reactions on a protected metallic structure.

Refractories

Non-metallic materials possessing exceptionally high melting points used primarily as linings for metallurgical furnaces.

Buttress Thread

A high-strength thread profile designed to transmit power unidirectionally, characterized by one perpendicular (square) load flank and one slanted flank.