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Fasteners and Welding

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

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Fasteners and Welding

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  1. Fasteners and Welding Lecture 22 Autumn Quarter

  2. 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

  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 Autumn Quarter

  4. Topics For Today • Importance of fastening • Threaded fasteners • Non-threaded fasteners • Other machine elements • Adhesives • Welding Autumn Quarter

  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 Autumn Quarter

  6. 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

  7. Threaded Fasteners – Terminology External Threads Autumn Quarter

  8. Threaded Fasteners – Terminology • Internal threads • Threads inside a hole • Made by drill & tap: • drill smooth hole • make threads with a tap Autumn Quarter

  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 Autumn Quarter

  10. Threaded Fasteners – Specification Example of a typical thread specification (in inches) • .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) .5 - 28 UNC - 3 B *There are several thread forms. UN is common. Autumn Quarter

  11. Threaded Fasteners – Specification Continuation of example of a typical thread specification (in inches) • 3 - class of fit (3 is precise, 2 is normal, 1 is loose fit) • B - internal thread (A is for external) .5 - 28 UNC - 3 B Autumn Quarter

  12. Threaded Fasteners – Specification Example of a typical metric thread specification • 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) M6 x 1 - 4H5H Autumn Quarter

  13. 1. End View Detailed 2. Schematic Representing External Threads • Options for representing external threads in a drawing Autumn Quarter

  14. End View Unsectioned Schematic(in section) Detailed(in section) Representing Internal Threads Options for representing internal threads Autumn Quarter

  15. Non-Threaded Fasteners • Rivets • Pins • Keys • Retaining rings • Locking washers Autumn Quarter

  16. Other Machine Elements • Springs • Bushings • Bearings (See references for more details) Autumn Quarter

  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 Autumn Quarter

  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 9.8 in BTG) Autumn Quarter

  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 Autumn Quarter

  20. Reference Line Leader Tail Welding Symbol Autumn Quarter

  21. Fillet Weld Weld around Opposite side Arrow side Welding Symbol – Example Specification Result Autumn Quarter

  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 Autumn Quarter

  23. References • Threaded and Other Fasteners • BTG Chapter 9, Appendices A24 – A42 • Welding • BTG Appendix B.25 Autumn Quarter

  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 Autumn Quarter

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