Engineering 28 University of California

• Lecture # 21– Formal Engineering Drawings– Drawing header– Working drawings

• Detail drawing• Outline assembly• Exploded assembly• Sectioned assembly• Material list

Making Something

• Design, sketch• Solid model• Formal Drawing

– Instruments– 2D CAD– Extract from solid model

• Fabrication shop• Inspection• Assembly

Needs formal drawing

Informal Drawings

A Formal Drawing

A Formal Drawing

• Multi-Views• Sections Views, Auxiliaries, Details• Dimensions• Tolerances• Drawing types• Drawing formats• Additional specifications

Done!

Legal Interpretations• An engineering drawing is a legal document• A part or device manufactured to within its

drawing specifications must be purchased, if under contract

• Parts can be refused for not meeting any one specification

• Professional level presentation is an expectation in the engineering and business world

• The professional quality of a person or company is proclaimed in the presentation quality of its drawings

Typical Drawing…

Information on a Drawing

• Views– Shows object in as many standard, section,

auxiliary, and detail views as necessary to define the object

– Shows dimensions and sizes as required– Shows tolerances as required– Usually includes a pictorial for clarity

Information on a Drawing

• Header– Contains additional information about material,

conditioning, and tolerances– Contains information about the ownership of

the information on the drawing– Contains information about design history– Contains information about how to interpret the

drawing

Information on a Drawing

• Notes– Anything that needs to be said that is not

already contained on the views or on the header

Drawing Sizes…

Printing on Letter Sized Sheets…

Formal Drawing Formats

• Each company may have a slightly different format

• Differences superficial• Essential information is same

ANSI Title Blocks

ANSI Continuation Blocks

Types of Formal Drawings• Outline Assembly (also “Layout Drawing”)

– shows fit of parts and function of device

• Exploded Assembly– shows how to assemble parts

• Sectioned Assembly– shows fit of parts that are otherwise hidden from view

• Detail Drawing– shows dimension and specifications of individual parts

• Material List– lists all parts and materials used

Sample Drawings…

The Vise Clamp

Material List

Exploded Assembly Drawing

More on Exploded Assemblies…

• An assembly or subassembly has its own part number

• Shows all parts, including commercial parts• All parts have balloons and item numbers• Shows how parts are to be put together, and

infer the sequence of assembly• Proper orientation is important• Assembly lines are used• No dimensions

Material List

Exploded Assembly Drawing

More on Material Lists…

• May be free standing or part of an assembly drawing

• Shows item numbers• Shows corresponding part numbers• Shows basic material used in each part• Shows number of instances each part is

used in the assembly• For large projects, shows the weight of each

part

Outline Assembly Drawing

Continuation of previous drawing

More on Outline Assemblies…

• Shows all parts, including commercial parts• All parts have balloons and item numbers• Shows how parts appear in their final

position on the assembly• Dimensions not shown, except assembly

dimensions• May contain functional specifications as

well as geometric specifications

Sectioned Assembly Drawing

Continuation of previous drawing

More on Sectioned Assemblies…

• Reveals parts otherwise hidden in the outline assembly

• Parts have balloons and item numbers• Shows how parts appear in their final

position on the assembly• No dimensions

Detail Drawing

More on Detail Drawings…

• Shows a single part• Shows dimensions• Shows tolerances• Specifies surface finishes and surface

treatments• Specifies materials• Contains sufficient information for

fabrication of the part by a third party

What Exactly is a “Part”?

• Example: alternator for an automobile Is this a part or an assembly

• For an alternator maker, it is an assembly• For an automobile make, it is a part• For you, a part is a single piece that you

either fabricate yourself, or receive as a single piece from a third party, ready to install into an assembly that you make

What Exactly is an “Assembly”?

• A main assembly is something you put together and ship to your customer as a complete product– Main assemblies may consist of parts and/or

subassemblies• A sub-assembly is a collection of part or

smaller sub-assemblies that you put together and handle as a single unit when it is installed into the main assembly– Sub-assemblies may consist of parts and/or

smaller sub-assemblies

End

• Questions?