GD&T + Surface TERMS Test

Tolerance Limit

The variation, positive or negative, by which a size is permitted to depart from the design size.

Actual Size

A measured size.

Limits of Size

The maximum and minimum sizes permitted for a feature.

Nominal Size

Size designation used for the purpose of general identification.

Basic Size

Size from which the limits of size are derived by the application of allowances and tolerances.

Datum

Theoretically exact surface, plane, axis, center plane, or point from which dimensions for related features are established.

Tolerance

The difference between the maximum and minimum size limits on a part.

Design Size

The basic size with allowance applied.

Specified Dimension

part of the dimension from which the limits are calculated.

Locational Clearance Fits

The standard fit LC, stands for what?

Zero Line

Line of zero deviation and represents the basic size.

Fit

The general term used to signify the range of tightness that may result from the application of a specific combination of allowances and tolerances in the design of mating parts.

Actual Fit

The relation between two mating parts with respect to the amount of clearance or interference that is present when they are assembled.

Transition Fit

The relationship between assembled parts when either a clearance or an interference can result, depending on the tolerance conditions of the mating parts.

Locational Transitional

The standard fit LT, stands for what?

Upper Deviation

The algebraic difference between the maximum limit of size and the corresponding basic size.

Allowance

prescribed difference between the maximum material limits of mating parts. The minimum clearance and maximum interference between such parts.

Running or Sliding

The standard fit RC, stands for what?

Maximum Material Condition

limit of size that provides the maximum amount of material for a part

Bilateral Tolerance

A tolerance in which variation is permitted in both directions from the design size.

Feature

Any physical portion of an object such as a surface or hole.

Locational Interference fit

The standard fit LN, stands for what?

Fundamental Deviation

That one of the two deviations closest to the basic size.

Dimension

Geometrical characteristic such as diameter, length, angle, or center distance.

Force or Shrink Fit

The standard fit FN, stands for what?

Least Material Condition

limit of size that provides the minimum amount of material for a part

Lower Deviation

the algebraic difference between the minimum size limit and the basic size

Unilateral tolerance

A tolerance in which variation is permitted in only one direction from the design size

Real surface obtained by instrumental or other means-definable

MEASURED

Profile of nominal surface

NOMINAL PROFILE

Actual or deviation from nominal

REAL

Representation of a measured real profile

MEASURED PROFILE

Profile of a real surface

REAL PROFILE

Average spacing between adjacent peaks

ROUGHNESS SPACING

Topography obtained by filtering out waviness

ROUGHNESS TOPOGRAPHY

Measurements of profile in a direction normal or perpendicular to the nominal profile

HEIGHTS

Obtained the same way as measured, but filters are added to pinpoint certain characteristics

MODIFIED PROFILE

Contour of surface measured normal or perpendicular to surface-unless specified

PROFILE

Measured profile with waviness filtered out

ROUGHNESS PROFILE

Measured profile with exaggeration of height or space without filtering

TOTAL PROFILE

Boundary of an object that separates that object from another object, Substance or space-area

SURFACE

Unintentional, unexpected, and unwanted interruptions in the topography

FLAWS

Fine irregularities of the surface texture resulting from the production process or material condition

ROUGHNESS

Topography obtained by measurement

MEASURED TOPOGRAPHY

Deviation from the nominal surface

ERROR OF FORM

Intended surface contour, shape and extent- perfect word

NOMINAL

Repetitive or random deviations from real

SURFACE TEXTURE

Profile with roughness and part form parameters removed

WAVINESS PROFILE

Nominal space measured for surface characteristics

SAMPLING LENGTH

Direction of predominant surface pattern

LAY

Dist. between specific points on a profile measured parallel to the nominal profile

SPACING

Parallel line to profile from which deviations are measured

MEAN LINE

Point of maximum height on that portion of a profile that lies above the meal line and between two intersections of the profile with the mean line

PEAK