This document discusses assembly drawings, which show how parts fit together to form a complete assembly. Assembly drawings typically include balloons to label parts, and a parts list that corresponds to the balloon numbers and provides information about each part. Different types of assembly drawings are used for different purposes, such as general assemblies, design assemblies, and pictorial assemblies. Guidelines are also provided for creating balloons and parts lists.

1. Assembly Drawings,
Balloons,
and
Parts Lists

2. A design that has been approved for prototype or
full-scale manufacture requires a set of working
drawings to communicate the object’s geometry to
everyone involved with its manufacture and
assembly.
Working drawings are a complete set of
documents that include:
Working Drawings
• Individual part drawings
• One or more assembly
drawings
• A parts list

3. Assembly Drawings
An assembly drawing shows how all of the
parts of a multi-component design fit together,
and are generally depicted as one or more
orthographic projections.
One or more full section views are often used
in an assembly drawing to show necessary
internal features.

4. Example Assembly Drawing

5. Information from Assemblies
• One or more views, including sections or auxiliaries
• Enlarged views to show small details
• Overall or specific dimensions needed for assembly
• Notes on manufacturing processes required for
assembly
• Balloons to indicate item numbers
• Parts list or bill of materials (BOM)
Assembly drawings may contain the
following:

6. • Design Assembly
• General Assembly
• Detail Assembly
• Erection Assembly
• Subassembly
• Pictorial Assembly
Types of Assembly Drawings

7. Design assemblies are used to
show various relationships
between components.
The design assembly at the right
shows the kinematic relationship
that exists between the fly
wheel’s 360° rotation, and the
extreme angular motion of the
piston cylinder body.
Design Assembly

8. Design assemblies are often made from sketches
during the preliminary phases of a design process
to study the relationships that exist between the
components before the design is modeled.
Design Assembly

9. A general assembly is the
most common type of
assembly drawing. It is
displayed as a multiview
drawing and may contain a
section view.
General assemblies do
not contain dimensions.
General Assembly

10. Detail Assembly
A detail assembly is a combination of an
assembly view with several of its parts
depicted as dimensioned multiview drawings
on one drawing sheet.
This practice, though not common, reduces
the number of drawing sheets needed, and is
more appropriate for designs with small
numbers of components.

11. Example Detail Assembly

12. Erection Assembly
• Similar to general assemblies, except
dimensions and fabrication specifications are
commonly included.
• Typically associated with cabinetry or products
that are made from structural steel.
• Used for both fabrication and assembly.

13. Subassembly Drawing
Complex or large
assemblies may be
communicated through
subassembly drawings.
Flashlight Subassembly

14. Pictorial Assembly
• Usually depicted as an
isometric or perspective
drawing.
• May be rendered to imitate
photographic quality.
• Uses include:
- Sales promotion
- Customer self-assembly
- Maintenance procedures

15. Pictorial assemblies are
often used in catalogs,
journal articles, and
advertisements.
This pictorial is
sectioned to show
interior details.
Pictorial Assembly Drawings

16. Exploded
pictorial
assembly
drawings are
commonly used
to show how
individual
components fit
together.
Pictorial Assembly Drawings

17. Balloons
A balloon is a
circle that
contains a
single number,
which is
connected to an
assembly
component with
a leader line.

18. • All balloons on a drawing should be the same
size.
• Balloons should be grouped together in an easy-
to-read pattern.
• Balloon numbers must correspond to item
numbers in a parts list.
• Balloons should not have horizontal or vertical
leader lines.
Balloon Guidelines

19. A parts list is a
table that contains
information about
each of the parts
contained in an
assembly. The
item numbers
correspond with
the balloon
numbers.
Parts List

20. Example Parts List

21. Parts List Information
• Item number – from balloons.
• Quantity – the number of a particular part needed
for the assembly.
• Part or drawing number – a reference back to the
detail drawing.
• Description – usually the part name or complete
description of a purchase part.
• Material identification – the material of the part.
• Information about vendors – for purchase parts.
Items commonly found in a parts list include:

22. Parts List Location
• Above the title block – most common
• Upper right corner
• Upper left corner
• A convenient location on the drawing
The location of a parts list usually depends on
company standards. Common locations
include:

23. Parts List Location