Machine Design, Shop Practice, and Materials Flashcards

Vocabulary practice flashcards covering mechanical engineering shop practice, machine tools, metallurgy, heat treatment, gears, and materials testing.

Annealing

A heat-treatment process involving heating above the transformation range, usually 1300°F to 1350°F, and cooling slowly (preferably in a furnace) to soften the metal and improve machinability.

Hardening

The process of heating steel to a temperature within or above the critical/transformation range and rapidly quenching, usually in oil or water, to increase hardness.

Tempering

Reheating a hardened metal to a temperature below the transformation range, followed by any desired rate of cooling to obtain desired mechanical properties.

Stress Relieving

Heating to a subcritical temperature around 1,100°F to 1,300°F and holding for a suitable duration to reduce internal residual stresses.

Normalizing

Heating steel to approximately 100°F above the transformation range followed by cooling freely in still air at room temperature to produce a uniform structure.

Quenching

The rapid cooling of a heated piece of work by immersing or dipping it in water, brine, or oil.

Shaper

A machine tool used principally to machine flat or plane surfaces using a single-point cutting tool that reciprocates while the feed is stationary.

Planer

A machine tool used for producing flat surfaces on pieces too large, heavy, or awkward to hold in a shaper, where the work reciprocates while the tool remains stationary.

Milling Machine

A machine tool used to produce a variety of surfaces by removing metal with a revolving circular cutter having multiple teeth.

Broaching Machine

A machine tool used to finish internal or external surfaces, such as holes or keyways, by pulling or pushing a cutter called a broach which has a series of cutting teeth.

Lathe Machine

A metal-turning machine tool where the workpiece revolves on a horizontal axis while a cutting tool feeds parallel or perpendicular to the work axis.

Slotter

A machine tool very similar to a shaper, except that its ram reciprocates vertically rather than horizontally.

Mandrel

A tool that, when pressed into a finished hole in a workpiece, provides centers upon which the piece can be turned or machined.

Live Center

A lathe center that fits into the main spindle and revolves with the work, acting as a bearing surface.

Dividing Head

A mechanism attached to a machine tool (such as a milling machine) used to perform indexing operations.

Pitch Circle

An imaginary circle passing through the points at which the teeth of meshing gears make contact with each other.

Diametral Pitch

The number of gear teeth per inch of pitch diameter, serving as an indication of tooth size.

Circular Pitch

The distance from the center of one gear tooth to the center of the next consecutive tooth, measured along the pitch circle.

Addendum

The radial distance that a gear tooth projects above or outside the pitch circle to the top land.

Dedendum

The portion of the gear tooth space cut below the pitch circle, equal to the addendum plus clearance.

Whole Depth

The total depth of a tooth space, equal to the sum of the addendum and the dedendum.

Backlash

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

Module

The ratio of the pitch diameter to the number of gear teeth (in millimeters or inches per tooth).

Gear Rack

A straight toothed bar that, when meshed with a gear (pinion), converts rotary motion into reciprocating linear motion.

Worm Gears

A type of gearing used for heavy-duty work requiring large speed ratios between non-intersecting shafts, widely used in speed reducers.

Bevel Gears

Gears used to transmit motion and power between intersecting shafts positioned at an angle to each other.

Tolerance

The total permissible variation in the size of a dimension; the difference between the maximum and minimum limits of size.

Interference of Metal

A condition in fits (negative allowance) where the internal member (shaft) is larger than the external member (hole), requiring force to assemble.

Carriage Bolt

A bolt with a rounded head and a square neck underneath designed to prevent turning in wood when the nut is tightened.

Stud Bolt

A headless bolt that has screw threads on both ends, used where a standard through bolt cannot be applied.

Tap

A cylindrical steel tool with flutes running lengthwise and intersecting threads that form cutting edges used to cut internal threads.

Feeler Gage

A set of precision thin steel strips of varying thicknesses mounted in a holder, used for measuring and checking clearances.

Micrometer

A precision measuring instrument capable of accurately measuring diameters down to a thousandth of an inch.

Torque Wrench

A hand tool used to measure and apply a specific tension or tightening torque to bolts.

Knurling

The process of forming a textured pattern or checkered depressions onto the surface of a workpiece by rolling hardened wheels against it.

Brazing

A joining operation in which a non-ferrous filler metal melts at a temperature below that of the base metals joined, but above 450°C.

Flywheel

A heavy rotating body that acts as a reservoir for absorbing and redistributing kinetic energy to prevent sudden changes in speed.

Endurance Limit

The maximum stress induced in a material subjected to alternating or repeated loading that it can withstand indefinitely without causing failure.

Elastic Limit

The maximum stress to which a material can be subjected without retaining any permanent deformation upon complete withdrawal of the load.

Poisson's Ratio

The ratio of the lateral strain to the longitudinal strain in a material subjected to axial stress.

Creep

The phenomenon of continuous slow stretching or deformation over time under sustained load, even when stress is below the yield point.

Resilience

The capacity of a material to absorb energy when deformed elastically and return that energy upon release of the load.

Plasticity

The mechanical property enabling a metal to undergo considerable permanent deformation without rupture.

Brass

A non-ferrous alloy composed principally of copper and zinc.

Bronze

A non-ferrous alloy composed principally of copper and tin.

Babbitt

An anti-friction bearing metal alloy composed of tin, copper, antimony, and sometimes lead.

Galvanized Iron

Iron or steel coated with a protective layer of zinc to prevent corrosion.

Refractories

Ceramic materials employed where resistance to very high temperatures is required, such as in furnace linings and melting crucibles.

Sintering

The heat treatment in powder metallurgy where cold-pressed metal powder is heated below its melting point to bind the particles together.

Autofrettage

The process of pre-stressing a hollow cylindrical pressure vessel by subjecting it to internal pressure beyond the elastic limit to induce residual compressive surface stress.

Fretting

Surface deterioration occurring when two contacting surfaces subjected to high contact pressure experience minute relative oscillatory motion.

Coaxing

The procedure of increasing the fatigue limit of a metal by subjecting it to repeated cyclic loads just below the fatigue limit, followed by successively increasing increments of load.