Introduction to Engineering Drawings

By: Chris VandelaarUniversity Machine Services

TEB Rm. 50

Resources: Doug Phillips – Previous MME259A presentation Interpreting Engineering Drawings 3rd edition by Jensen & Hines

Engineering Drawings:The language of manufacturing

How we communicate our intentions as designers

Convey all necessary information to get things made, manufactured, modified, assembled

Engineering Drawings:

Can be quite simple

Hydraulic Piston - Simple Part?

Engineering Drawings:

Can be complex

Engineering Drawings:Contain only pertinent information

To ensure all engineering specifications and requirements are met

What is pertinent

• Form – shape of the part• Geometry – acceptable deviation from form• Dimensions – sizes of forms and shapes• Tolerances – acceptable deviation from

dimensions• Surface finish and or treatment• Other General information - notes

Pertinent information???Form:

Shown with picturesOrthographic projectionOrthographic views

This shows: Third Angle Projection

Projection Standard is communicated by Simple Projection Symbols

First Angle Projection: ISO/Europe• Like rolling the part on a table

Third Angle Projection: North America• Like walking around the part

Projection Symbols:The very first thing a manufacturer looks for.

EXTREMELY IMPORTANT!

Orthographic ViewsSometimes can’t show everything

Additional Views may be required

Additional Views Include:•Section Views•Cut-away Views•Broken Views•Revolved Section Views

Not as common

Section view – shows part form along specified line(s) – “SECTION LINE” (dashed)

Cut-away View – shows part form behind front face

Break Views:• Allow use of larger scale for larger parts

– Smaller drawings

Break View – for long parts

Notice Important Features of Break View:•Instance numbers-Indicate number of spaces and holes•Break line in overall length dimension – Indicates the presence of a break view

Break LinesShorten views to better fit the page

Revolved Section Views – Show profile forms

Difficult to do using solidworksNot very common these days

Engineering Drawings: Contain only pertinent information

PicturesOrthographic and alternate views

Lines – Different lines mean different things

Line Types• Object Lines – Show Part Geometry or Form

– Visible – (Solid Lines)• Illustrate external features and outlines• As if looking at the part

– Hidden – (Dashed Lines) • Illustrate anything behind the front face of the view• As if looking through the part

– Phantom – • Show non existent/alternate parts or features

Object and Hidden Lines

Phantom Lines:

Line Types• Object Lines – Show Part Geometry or Form

– Visible – (Solid Lines)– Hidden – (Dashed Lines) – Phantom – (Dotted or short /long dash lines)

• Reference Lines – Show references– Center Lines – Long/short dash (alternating)– Section Lines – indicate views (short dash)

Reference Lines:

Line Types: Review

Engineering Drawings: Pertinent information

PicturesOrthographic views

Lines – Different typesDimensions – Show feature sizes

Dimension Types:Standard - incrementalBase Line – absoluteOrdinate – absolute

Incremental: point to point – one position to the next

Absolute: reference one single point (DATUM)

Dimension Types: ANSI Standards shown

Baseline OrdinateAbsolute

StandardIncremental

OrdinateAbsolute

Other Dimensioning:

Simple holes(mm)

More complex holes(SAE – Inches)

Other Dimensioning:

Engineering Drawings: Pertinent information

PicturesOrthographic and alternate views

Lines – Different typesDimensions – Show feature sizes

Tolerances – Allowable deviation from size

Tolerance Types:• Basic – standard tolerance from title block• Bilateral – shows allowable deviation from nominal –

above or below• Limit – gives two dimensions – anything in between

accepted• Symmetric – gives one tolerance – above or below

nominal• Min/Max – anything over or under• Fits – alone, with, or without tolerance

– References standard Engineering fits

Standard Fits:

Engineering Drawings: Pertinent information

PicturesOrthographic and alternate views

Lines – Different typesDimensions – Show feature sizes

Geometric Dimensioning and tolerancing – (GD&T)

Geometric Dimensioning and Tolerancing:

GD&T• The allowable deviation from

nominal form

GD&T Uses:1.Datum – point of reference

– Face, Edge or Hole

2.Symbol – type of deviation3.Tolerance – allowable variation

– Given as distance

Example of Geometric tolerance:

Example of Geometric tolerance: Labelled

GD&T uses symbols to communicate geometric specifications

Which area of this block is out of tolerance?

GD&T is the only way to guarantee correct form

Dimensions only guarantee size

Drawing views:Contain some or all of the following:1.Dimensions2.Tolerances3.Geometric Tolerancing4.Surface finish information5.Allowable tool mark information

Drawings Contain:1.Drawing Templates or Borders2.Drawing Views3.Title Block4.Revision Block5.Notes – special or standard

Title Blocks:Can vary in:

– Size– Content– Location

TITLE BLOCKS :Contain any information that cannot be communicated through orthographic views and dimensions.

Examples: (not limited)•Part materials•Part quantities•Authors – supervisors – inspectors•Inspection information/standard•Finishing info – Painting, anodizing, heat treating•Customer info•Company Info

Special Notes:•Can be located anywhere on the drawing – In title block or specific views.•Some times drawing views have notes that simply say, “SEE NOTE #” referring to standard notes in the notes field.

Examples:1.See Note #? (in drawing pain)2.Supplier info (notes field)3.Clearance hole only (in drawing pain view attached to dimension)4.Remove all sharp edges unless specified (Notes field)5.Part to be painted as per manufacturers instruction and specification (notes field)6.Surface treatments as per ASTM standard “- - - -“ (notes field)7.Any information at all required to achieve design intention.

FOR NON-STANDARD INFORMATION

THE ENDIntroduction to Engineering

DrawingsBy: Chris Vandelaar

University Machine ServicesTEB Rm. 50

Resources: Doug Phillips – Previous MME259A presentation Interpreting Engineering Drawings 3rd edition by Jensen & Hines