1. Question of the Day
Who invented the zipper and what year was it invented?
ANSWER:
Whitcomb L. Judson, 1893
Lecture 22 - AutoCAD

2. What’s Coming Up? Today Tuesday Wednesday Thursday Fasteners & Welding
Working Drawing Set
Wednesday
Measurements Lab
Thursday
Quiz on Fasteners and Welding
Introduction to AutoDesk Inventor
Lecture 22 - AutoCAD

3. 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
Lecture 22 - AutoCAD

4. Topics For Today Importance of fastening Threaded fasteners
Non-threaded fasteners
Other machine elements
Adhesives
Welding
Lecture 22 - AutoCAD

5. 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
Lecture 22 - AutoCAD

6. Three Methods Commonly Used in Fastening
Mechanical Fastening
Bolts, rivets, keys, pins
Paper clips, zippers, “Velcro”
Bonding
Welding, soldering, brazing, gluing
Forming
Sheet metal, plastic snaps parts
Lecture 22 - AutoCAD

7. Threaded Fasteners – Terminology
External Threads
Lecture 22 - AutoCAD

8. Threaded Fasteners – Terminology
Internal threads
Threads inside a hole
Made by drill & tap:
drill smooth hole
make threads with a tap
Lecture 22 - AutoCAD

9. 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
Lecture 22 - AutoCAD

10. Threaded Fasteners – Specification
Example of a typical thread specification (in inches)
UNC - 3 B
.5 - major diameter of .5 inches
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.
Lecture 22 - AutoCAD

11. Threaded Fasteners – Specification
Continuation of example of a typical thread specification (in inches)
UNC - 3 B
3 - class of fit (3 is precise, 2 is normal, 1 is loose fit)
B - internal thread (A is for external)
Lecture 22 - AutoCAD

12. 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)
Lecture 22 - AutoCAD

13. Representing External Threads
Options for representing external threads in a drawing
Schematic 2. 1.
End View
Detailed
Lecture 22 - AutoCAD

14. Representing Internal Threads
Options for representing internal threads
Schematic (in section)
Detailed (in section)
Unsectioned
End View
Lecture 22 - AutoCAD

15. Non-Threaded Fasteners
Rivets
Pins
Keys
Retaining rings
Locking washers
Lecture 22 - AutoCAD

16. Other Machine Elements
Springs
Bushings
Bearings
(See references for more details)
Lecture 22 - AutoCAD

17. 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
Lecture 22 - AutoCAD

18. 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 10.9 in FGC)
Lecture 22 - AutoCAD

19. Welding Symbol Reference Line Leader and arrow
Basic weld symbol (location & depth of weld)
Finish symbol
Weld symbol
Dimensions
Supplementary symbols
Tail and specifications
Lecture 22 - AutoCAD

20. Welding Symbol
Leader
Reference Line
Tail
Lecture 22 - AutoCAD

21. Welding Symbol – Example
Fillet Weld
Weld around
Opposite side
Arrow side
Lecture 22 - AutoCAD

22. 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
Lecture 22 - AutoCAD

23. References Threaded and Other Fasteners Welding
BTG Chapter 9, Appendices A24 – A42
Welding
BTG Appendix B.25
Lecture 22 - AutoCAD

24. 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
Lecture 22 - AutoCAD