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Engineering Drawings:

Detail Drawings

A short lecture on Detail Drawings as per the Australian Standard AS By Paul Briozzo

What is a Detail Drawing?

An Engineering Detail Drawing contains the key points to enable the manufacture or description of a single component that defines and communicates part of a complete design to other interested parties.

Detail Drawings must provide sufficient information to enable the

manufacture a part.

• Enough orthogonal views : enough views to adequate describe the component.
• Dimensions : Must be evenly distributed, structured and not duplicated.
• Scale : Drawing must state the scale used to fit the component onto the drawing sheet.
• The type of projection : Third Angle Projection is mandatory in ENGG1960.
• Drafting Standard (AS1100) : This is effectively covered in prescribed texts.
• The name or title of drawing : What is the name of the component?
• The drawing number : What is the number (in-house system) of the component?
• Dimensional units used : mm, m, inches, feet etc.
• Tolerances : What are the manufacturing tolerances for each part of the component.
• Surface texture (or roughness) : How smooth/rough each part of the component has to be.
• Treatments (coatings, tempers etc.) : Does the component need protective coatings?
• Reference to assembly drawing : What does my component fit into?
• Material : What material is the component manufactured from?
• Drafter (who drew it), Checker (who checked it), Approver (who approved it) and dates
• Zones : Where on the drawing are you referring to?
• Revision : What has been revised and why and what revision is this drawing?
• Sheet Size : A4, A3, A2, A1 or A
• Company : School of AMME, University of Sydney
• Sheets Reference (eg. Sheet 1 of 3) : When more than one sheet is required.

Enough Orthogonal Views

Wall Bracket drawing shows three regular views. Could have been done with two regular views and a sectional view replacing the end elevation.

Scale

Wall Bracket drawing shows the scale to which the drawing is drawn within the title block as is required by AS1100. The scale in this case is 1:1 or “Full Size” other preferred scales in the metric system are:

For enlargement: 2:1, 5:1, 10:1, 20:1, 50: For reduction: 1:2 (half size), 1:2.5, 1:5, 1:10, 1:20, 1:50, 1:100, 1:200, 1: 1:1000, 1:2000, 1:5000, 1:10 000

The Type of Projection

rd

Angle)

Wall Bracket drawing shows the Third Angle Projection Symbol within the title block. The symbol is sometimes located outside of the title block. The conical cylinder represents the orientation of views that should be reflected in your drawings.

Name or Title of Drawing /

Drawing Number

The drawing shows its name, WALL BRACKET within the title block. The name or title of the drawing is the name by which (in this case) the detail drawing is commonly referred to by many parties involved. This name is not unique.

The drawing number (abbreviated to DRG N o^ ) is the part number which is often used to locate or recognise the part within a database. This number is unique.

There may be many parts that are named “WALL BRACKET”. However, the number of the drawing must be unique.

Dimensional Units Used

The units used throughout the drawing. In this case millimetres are used. However other metric or imperial units may be used. E.g. microns, metres, inches or feet. Centimeters are not used in Engineering Drawings.

Surface Texture or Roughness

Symbols which indicate the surface texture of roughness that a component or a particular feature of a component requires must be inserted.

The surface texture symbol should be located so that it can be read from the bottom or right hand side of the drawing.

Standard Roughness Values

Reference to Assembly Drawings

Detail drawings seldom describe the intent of an engineering design. An engineering design is usually defined by many individual detail drawings which combine to form an assembly drawing. The name and or drawing number of the assembly drawing in which the detail drawing is “called up” or “used on” is stated in the title block.

Material

Engineering designs are highly dependant on the material from which they are manufactured. Clearly this is something that must be stated in the drawing as it vital information that must be passed on to the manufacturer of the part and many other parties. This information is normally stated in the title block. If the information is extensive a separate note located in the drawing or a separate data sheet may be used.

Zone Reference System

The numbers and capital letters surrounding a drawing provide a method whereby two people may discuss (perhaps over a telephone call) a particular feature on a drawing. This is most useful on large format sheets such as A0 and A1 sizes.

Revisions or Modifications

Revisions to designs may occur due to design development, manufacturing process refinement or the removal of errors. These changes require revisions to all of the drawings affected. In the drawing above, a revision is noted regarding the change of thread from 5/8” Whitworth to M16 Metric. There is usually more documentation associated with these changes than is noted in this example.