ME 441 Quiz 2

Counterbore

the larger hole is drilled straight into the material at a shallower depth than the smaller inner shaft. This leaves a flat bottom for the fastener to rest on

Countersink

The larger hole is drilled at an angle, ideally to match the tapered angle of the fastener

R

The letter used to denote the radius of the circle. Used when there is a curve that is not a complete circle (Arcs, sweeps, etc.)

Mating Dimensions

The term for the dimension on mating parts that allows them to fit together when assembled

Tolerance

The total variation from the specified dimension a part can have and still be deemed acceptable

Inversely

Tolerances are ____ related to cost. That is the less variation allowed, the more the part will cost to manufacture

Generous

Tolerances should be as ______ as possible while still maintaining proper function for the part

Nominal Value

The measured value may vary in the positive or negative direction an equal tolerance and still be acceptable

Nominal Dimension

Given with tolerances expressed as an acceptable plus/minus range

Limit Dimensions

Specify the upper and lower tolerance limit. An acceptable part may be at the upper limit, lower limit, or specified range

Fit

How tightly or loosely parts must fit together when assembled to function properly

Maximum Material Condition

when the shaft diameter is maximum and the hole diameter is minimum

Allowance

The minimum clearance or maximum interference when features are at their maximum material condition

Clearance Fit

Internal member always has space or clearance from the external chamber

Interference Fit

Internal member is always larger and has to be forced into the external chamber

Transition Fit

Either tolerance or interference

Line Fit

Clearance or surface contact results

Basic Shaft System

Maximum size of the shaft is the basic dimension

Basic Hole System

The hole machined with a standard sized took; therefore, the hole is the basis for the tolerances

Angular Tolerances

Angled surfaces be perfect near the vertex of the angle, but can vary more along the length of the angled feature

Position

What symbol is this?

Concentricity

What symbol is this?

GD&T Symbols

Specifies the tolerances based on the geometric shapes of the object

Datums

Features on an object that are used as references from which other measurements are made

Bonus Tolerance

If the actual hole is is larger than the smallest allowable hole, this can be added to the stated tolerance value