Engineering
Drawing and Design
Seventh Edition
Chapter 14
14-1 Drawing quality assurance
• Design requirements
• Manufacturing
processes
• Understanding of
function and application
of the design
• Review considerations
• Drawing considerations
• Fabrication
considerations
• Assembly
considerations
14-2 Functional Drafting
• Functional drafting must embrace every
possible means to communicate sufficient
information to produce or assemble parts in
the least expensive manner
• Drafting shortcuts can reduce time and
expense
Procedural shortcuts
• Streamlined approval requirements
• Eliminating the drawing check from the
preparation cycle
• Using standard and existing drawings
• Maintain standard drafting practices
• Team drafting-multiple people produce one
drawing
• Standard parts & design-standard information
Reducing the number of drawing
required
• Detail assembly drawings-parts are detailed in
place on the assembly
• Multi-detail drawings-separate detail views for
the assembly and each of its parts
• Care must be taken not to make these
drawings complicated and confusing
• Careful selection of the type of projection
(orthographic, isometric, oblique)
DETAIL AND ASSEMBLY DRAWINGS
DETAIL ASSEMBLY DRAWING OF A SAWHORSE
DETAIL AND ASSEMBLY DRAWINGS
ORTHOGRAPHIC PROJECTION
ISOMETRIC PROJECTION
SELECTING THE MOST SUITABLE TYPE OF PROJECTION
Simplified representation in drawings
• Symmetry symbols
• Threads
• Use simplified drawing practices as described
in the text
• New drawings made from existing drawings
• Photodrawings-engineering drawings into
which one or more photographs are
incorporated
DETAIL AND ASSEMBLY DRAWINGS
CONVENTIONAL
SIMPLIFIED
COMPARISON BETWEEN CONVENTIONAL
AND SIMPLIFIED REPRESENTATION
DETAIL AND ASSEMBLY DRAWINGS
CONVENTIONAL
SIMPLIFIED
COMPARISON BETWEEN CONVENTIONAL
AND SIMPLIFIED REPRESENTATION
DETAIL AND ASSEMBLY DRAWINGS
CONVENTIONAL
SIMPLIFIED
COMPARISON BETWEEN
CONVENTIONAL AND SIMPLIFIED REPRESENTATION
14-3 Detail Drawings
• Working drawing-a drawing that supplied
information and instructions for the
manufacture or construction of machines or
structures
– Detail drawings-provide the necessary information
for the manufacture of parts
– Assembly drawings-supply the necessary
information for assembly
Detail drawing requirements
• Shape description-select number of views to
describe the shape of the part
• Size description-dimensions
• Specifications-material, finish, tolerances…
• Additional drawing information-drawing number,
scale, method of projection, date, name of part,
drafter’s name
• Detailer-must have a thorough understanding of
materials, shop processes
• Manufacturing methods-the type of
manufacturing process influences material
selection and detailed feature of a part
14-4 Multiple detail drawings-detail
drawings can be shown on one or
multiple sheets
• Detailing is often grouped by the department in
which they are made
• Example: Electrical transformer
– Wood parts
– Fiber parts
– Metal parts
Separate detail sheets for each shop and one for
assembly. Identification part numbers are shown on
the detail drawing
DETAIL AND ASSEMBLY DRAWINGS
SIMPLE DETAIL DRAWING
DETAIL AND ASSEMBLY DRAWINGS
MANUFACTURING PROCESS INFLUENCES THE SHAPE OF THE PART
DETAIL AND ASSEMBLY DRAWINGS
MANUFACTURING PROCESS INFLUENCES THE SHAPE OF THE PART
DETAIL AND ASSEMBLY DRAWINGS
DETAIL DRAWING WITH MANY PARTS
14-5 Drawing Revisions
• Revisions are made to an existing drawing when
manufacturing methods are improved, to reduce
cost, to correct errors, and to improve design
• A clear record of these revisions must be
registered on the drawing
• A revision table should be on all drawings
• Numerous revisions often leads to a new drawing
– REDRAWN
– REVISED
14-6 Assembly Drawings
• Assembly drawing-a drawing showing the
product in its completed state
• Design assembly drawings-shows the
performance, shape, clearances of the various
parts shown
• Installation Assembly drawings
• Catalog assembly drawings
• Item list or Bill of Materials (BOM)-itemized
list of all components shown on the drawing
DETAIL AND ASSEMBLY DRAWINGS
DESIGN ASSEMBLY DRAWING (Timken Roller Bearing Co.)
DETAIL AND ASSEMBLY DRAWINGS
INSTALLATION ASSEMBLY DRAWING
DETAIL AND ASSEMBLY DRAWINGS
ASSEMBLY DRAWINGS USED IN CATALOG
DETAIL AND ASSEMBLY DRAWINGS
DETAIL AND ASSEMBLY DRAWINGS
14-7,8,9:Exploded,Detail,Sub Assembly
Drawings
• Exploded -help unskilled workers. Appliancerepair is a good example
• Detail- are made for fairly simple objects when
there are few parts
• Sub-for preassembled units that are further
assembled into a final assembly