Welding General
Transcript of Welding General
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Engineering H191 - Drafting / CAD
Gateway Engineering Education Coalition Lect 22 P. 1Autumn Quarter
Fasteners and Welding
Lecture 22
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Engineering H191 - Drafting / CAD
Gateway Engineering Education Coalition Lect 22 P. 2Autumn Quarter
Whats Coming Up?
Today
Fasteners & Welding
Tuesday
Working Drawing Set
Wednesday
Measurements Lab
Thursday Quiz on Fasteners and Welding
Introduction to AutoDesk Inventor
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Engineering H191 - Drafting / CAD
Gateway Engineering Education Coalition Lect 22 P. 3Autumn Quarter
Fasteners and Welding
Objectives:
Understand importance of fasteners, learn how
to specify threaded fasteners and represent
them in drawings and learn about otherfastening methods.
Understand basics of welding symbols
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Engineering H191 - Drafting / CAD
Gateway Engineering Education Coalition Lect 22 P. 4Autumn Quarter
Topics For Today
Importance of fastening
Threaded fasteners
Non-threaded fasteners
Other machine elements
Adhesives
Welding
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Gateway Engineering Education Coalition Lect 22 P. 5Autumn Quarter
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
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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
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Engineering H191 - Drafting / CAD
Gateway Engineering Education Coalition Lect 22 P. 7Autumn Quarter
Threaded Fasteners Terminology
External Threads
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Threaded Fasteners Terminology
Internal threads
Threads inside a hole
Made by drill & tap:
drill smooth hole
make threads with a tap
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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 otherend, NOT used with a nut
Machine screw - similar to cap screw but smaller
Set screw - used to prevent 2 rotating parts from
moving separately
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Engineering H191 - Drafting / CAD
Gateway Engineering Education Coalition Lect 22 P. 10Autumn Quarter
Threaded Fasteners Specification
.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)
Example of a typical thread specification (in inches)
.5 - 28 UNC - 3 B
* There are several thread forms. UN is
common.
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Engineering H191 - Drafting / CAD
Gateway Engineering Education Coalition Lect 22 P. 11Autumn Quarter
Threaded Fasteners Specification
3 - class of fit (3 is precise, 2 is normal, 1 is
loose fit)
B - internal thread (A is for external)
Continuation of example of a typical thread
specification (in inches)
.5 - 28 UNC - 3 B
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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)
Example of a typical metric thread specification
M6 x 1 - 4H5H
Threaded Fasteners Specification
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Schematic2.
1.
EndView
Detailed
Representing External Threads
Options for representing external threads in a
drawing
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Representing Internal Threads
Options for representing internal threads
Schematic(in section)
Detailed(in section)
Unsectioned End View
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Non-Threaded Fasteners
Rivets
Pins
Keys
Retaining rings
Locking washers
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Other Machine Elements
Springs
Bushings
Bearings
(See references for more details)
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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
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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 joindissimilar metals
Welding - parts to be joined and filler (if any) are
melted, pressed together and then cool. (See
Section 9.8 in BTG)
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Welding Symbol
Reference Line
Leader and arrow
Basic weld symbol (location & depth of weld)
Finish symbol
Weld symbol
Dimensions
Supplementary symbols Tail and specifications
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Welding Symbol
Leader
Reference Line
Tail
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Welding Symbol Example
Fillet Weld
Weld around
Arrow side
Opposite side
Specification Result
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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
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References
Threaded and Other Fasteners
BTG Chapter 9, Appendices A24 A42
Welding
BTG Appendix B.25
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Assignments
Dwg 43 FB-1D Fasteners
Answer questions about fasteners using thetables in the book.
Due Today Dwg 44 FD-3B Welding Symbology
Add notes to the Welding Symbols as neededto make them match the schematic
Due Tuesday Dwg 45 Working Drawing Set
A Handout will be provided in class