## ENG 004 Lecture 15, Nov 15, 2012

### Announcements

- Homework #6 due Tuesday, any questions?
- Read Chapter 10

### Topics

- Geometric Dimensioning and Tolerancing

## Tolerancing

Tolerancing is the art and science of using the largest tolerance possible
that will still allow a part to function.

## Table Example

## Geometric Dimensioning and Tolerancing

- A method of defining parts based on how the function, using standard
ASME/ANSI symbols.
- Size cotnrol is the first rule
- Supplements size control in that it allows for feature/geometry
control
- It uses a symbolic language

## Rule #1

### Individual Feature of Size

Where only a tolerance of size is specified, the limits of size of an
individual feature prescribe the extent to which variations in its geometric
form, as well as size, are allowed.

### i.e.

If a feature is dimensioned only with a traditional tolerance, then that
tolerance governs all of the tolerances for form. You only specify geomtric
dimensions and tolerances to supplement the tradiational size/location
tolerance.

## Datum

A starting place for a dimension such as a perfect plane, a center line,
or a point.

Datums are perfect, ideal constructs

In reality "perfection" of a datum can mean that it is at least 10 times
more accurate than the accuracy of the part being measured.

## Datum Symbols

## Datum

## Datum

## Feature Control Frame

Used to specify the geometric tolerances. It is divided into two or more
zones.

## Maximum/Least Material Condition

## Tolerance Zone

## Geometric Characteristics

## Tolerance Modifiers

## Flatness

## Circularity

## Cylindricity

## Straightness

## Parallelism

## Perpendicularity

## Angularity

## Concentricity

## Surface Profile

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