Transcript FEH - ENG H191 - Lecture 22

Engineering H191 - Drafting / CAD
Fasteners and Welding
Lecture 22
Autumn Quarter
Gateway Engineering Education Coalition
Lect 22
P. 1
Engineering H191 - Drafting / CAD
What’s Coming Up?
• Today
– Fasteners & Welding
• Tuesday
– Working Drawing Set
• Wednesday
– Measurements Lab
• Thursday
– Quiz on Fasteners and Welding
– Introduction to AutoDesk Inventor
Autumn Quarter
Gateway Engineering Education Coalition
Lect 22
P. 2
Engineering H191 - Drafting / CAD
Fasteners and Welding
• Objectives:
– Understand importance of fasteners, learn how
to specify threaded fasteners and represent
them in drawings and learn about other
fastening methods.
– Understand basics of welding symbols
Autumn Quarter
Gateway Engineering Education Coalition
Lect 22
P. 3
Engineering H191 - Drafting / CAD
Topics For Today
•
•
•
•
•
•
Importance of fastening
Threaded fasteners
Non-threaded fasteners
Other machine elements
Adhesives
Welding
Autumn Quarter
Gateway Engineering Education Coalition
Lect 22
P. 4
Engineering H191 - Drafting / CAD
Importance of Fastening
• 50% of production time for the average item is
spent on assembly/fastening.
• Fasteners are critical to product performance and
reliability
• Choosing the proper fasteners is an important
part of product design
Autumn Quarter
Gateway Engineering Education Coalition
Lect 22
P. 5
Engineering H191 - Drafting / CAD
Three Methods Commonly Used in
Fastening
• Mechanical Fastening
– Bolts, screws, rivets, keys, pins
– Paper clips, zippers, “Velcro”
• Bonding
– Welding, soldering, brazing, gluing
• Forming
– Sheet metal, plastic snaps parts
Autumn Quarter
Gateway Engineering Education Coalition
Lect 22
P. 6
Engineering H191 - Drafting / CAD
Threaded Fasteners – Terminology
External Threads
Autumn Quarter
Gateway Engineering Education Coalition
Lect 22
P. 7
Engineering H191 - Drafting / CAD
Threaded Fasteners – Terminology
• Internal threads
– Threads inside a hole
– Made by drill & tap:
• drill smooth hole
• make threads with a tap
Autumn Quarter
Gateway Engineering Education Coalition
Lect 22
P. 8
Engineering H191 - Drafting / CAD
Threaded Fasteners – Terminology
• Bolt - head on one end, threads on other end,
used with a nut
• Stud - rod threaded at both ends
• Cap screw - head on one end, threads on other
end, NOT used with a nut
• Machine screw - similar to cap screw but smaller
• Set screw - used to prevent 2 rotating parts from
moving separately
Autumn Quarter
Gateway Engineering Education Coalition
Lect 22
P. 9
Engineering H191 - Drafting / CAD
Threaded Fasteners – Specification
Example of a typical thread specification (in inches)
.5 - 28 UNC - 3 B
•
•
•
•
.5 - major diameter of .5 inches
28 - 28 threads per inch
UN - form Unified (i.e. shape of the thread)*
C - series (C means coarse), F (fine), EF (extra fine)
*
There are several thread forms. UN is
common.
Autumn Quarter
Gateway Engineering Education Coalition
Lect 22
P. 10
Engineering H191 - Drafting / CAD
Threaded Fasteners – Specification
Continuation of example of a typical thread
specification (in inches)
.5 - 28 UNC - 3 B
• 3 - class of fit (3 is precise, 2 is normal, 1 is
loose fit)
• B - internal thread (A is for external)
Autumn Quarter
Gateway Engineering Education Coalition
Lect 22
P. 11
Engineering H191 - Drafting / CAD
Threaded Fasteners – Specification
Example of a typical metric thread specification
M6 x 1 - 4H5H
• M - indicates thread form is metric
• 6 - major diameter in millimeters
• 1 - pitch in millimeters
• 4H5H - tolerance (capital letters for internal thread, lower case
for external thread)
Autumn Quarter
Gateway Engineering Education Coalition
Lect 22
P. 12
Engineering H191 - Drafting / CAD
Representing External Threads
• Options for representing external threads in a
drawing
1.
Detailed
End
View
2.
Schematic
Autumn Quarter
Gateway Engineering Education Coalition
Lect 22
P. 13
Engineering H191 - Drafting / CAD
Representing Internal Threads
Options for representing internal threads
Detailed Schematic Unsectioned
(in section) (in section)
Autumn Quarter
Gateway Engineering Education Coalition
End View
Lect 22
P. 14
Engineering H191 - Drafting / CAD
Non-Threaded Fasteners
•
•
•
•
•
Rivets
Pins
Keys
Retaining rings
Locking washers
Autumn Quarter
Gateway Engineering Education Coalition
Lect 22
P. 15
Engineering H191 - Drafting / CAD
Other Machine Elements
• Springs
• Bushings
• Bearings
(See references for more details)
Autumn Quarter
Gateway Engineering Education Coalition
Lect 22
P. 16
Engineering H191 - Drafting / CAD
Adhesives
• Used to join thin or dissimilar materials
• Seal a joint as well as bond it
• Can be used to coat threads and prevent
loosening
Autumn Quarter
Gateway Engineering Education Coalition
Lect 22
P. 17
Engineering H191 - Drafting / CAD
Thermal Fastening
• Soldering - solder (filler) melts but parts to be
joined remain at low temperature
• Brazing - filler is melted, and parts to be joined
are heated but do not melt. Can be used to join
dissimilar metals
• Welding - parts to be joined and filler (if any) are
melted, pressed together and then cool. (See
Section 9.8 in BTG)
Autumn Quarter
Gateway Engineering Education Coalition
Lect 22
P. 18
Engineering H191 - Drafting / CAD
Welding Symbol
•
•
•
•
•
•
•
•
Reference Line
Leader and arrow
Basic weld symbol (location & depth of weld)
Finish symbol
Weld symbol
Dimensions
Supplementary symbols
Tail and specifications
Autumn Quarter
Gateway Engineering Education Coalition
Lect 22
P. 19
Engineering H191 - Drafting / CAD
Welding Symbol
Reference Line
Leader
Tail
Autumn Quarter
Gateway Engineering Education Coalition
Lect 22
P. 20
Engineering H191 - Drafting / CAD
Welding Symbol – Example
Fillet Weld
Opposite side
Weld around
Arrow side
Specification
Autumn Quarter
Gateway Engineering Education Coalition
Result
Lect 22
P. 21
Engineering H191 - Drafting / CAD
Welding Symbol
•
•
•
•
•
Below reference line describes the ARROW side
of the weld
Above the line describes the OTHER side
Joint described by symbol (fillet, square)
Numbers by symbol indicate size
Circle at joint specifies weld around
Autumn Quarter
Gateway Engineering Education Coalition
Lect 22
P. 22
Engineering H191 - Drafting / CAD
References
• Threaded and Other Fasteners
– BTG Chapter 9, Appendices A24 – A42
• Welding
– BTG Appendix B.25
Autumn Quarter
Gateway Engineering Education Coalition
Lect 22
P. 23
Engineering H191 - Drafting / CAD
Assignments
• Dwg 43 – FB-1D – Fasteners
– Answer questions about fasteners using the
tables in the book.
– Due Today
• Dwg 44 – FD-3B – Welding Symbology
– Add notes to the Welding Symbols as needed
to make them match the schematic
– Due Tuesday
• Dwg 45 – Working Drawing Set
– A Handout will be provided in class
Autumn Quarter
Gateway Engineering Education Coalition
Lect 22
P. 24