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Threads and Fasteners

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Threads. and. Fasteners. Purpose. To fasten objects together. Common Fasteners: Nuts & bolts ... Course Threads, Fine Threads, Metric threads and whitworth. ... – PowerPoint PPT presentation

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Title: Threads and Fasteners


1
Threads and Fasteners
2
Purpose
  • To fasten objects together
  • Common Fasteners
  • Nuts bolts
  • Tapers
  • Rivets
  • Screws
  • Nails
  • Machine screws
  • Locking pins
  • Adhesives
  • Keys

3
Threads
  • Course Threads, Fine Threads, Metric threads and
    whitworth.
  • Course and fine are common imperial
  • Metric is common
  • Whitworth is the old British standard

4
Course Threads
  • Threads farther apart
  • Deeper cut
  • Best used with soft materials
  • Aluminum
  • Brass
  • Copper
  • Plastic

5
Fine Threads
  • Threads closer together
  • More thread contact for length
  • Common in harder metals

6
Metric
  • Has similar course and fine types
  • Measured differently
  • Different head markings

7
Whitworth Threads
  • Only found in old British cars
  • 55 thread instead of standard 60

8
Thread classification
  • UNC Unified national course
  • UNF Unified national fine
  • Standard measurement
  • Measured in threads per inch
  • Metric
  • Measured by the distance in mm between the treads

9
Measuring
  • Bolt Size Major Diameter
  • Bolt head size Distance between the flats of
    the hexagon

10
Measuring
  • Bolt length the distance from the base of the
    head to the end of the thread
  • Thread pitch Threads per inch Distance
    between threads

11
Grade
  • Tensile strength (pulling strength)
  • Amount of PSI the bolt can handle
  • Only accurate for bolts with a 1 inch diameter

12
Grade
  • Grade stamped on top
  • Imperial grade number of lines Two
  • Metric Grade is printed
  • 5D, 8G, 10K, 12K.

13
Under load
  • When a bolt goes past its load capacity it
    reaches its elastic limit
  • After elastic limit the bolt stretches and looses
    strength

14
Torque Specs
  • All bolts on a vehicle have a special
    specification that they have to be tightened too.
  • Always look this up in the manual before
    tightening any thing

15
Flat Washers
  • Used to make larger bearing surfaces for nuts to
    ride on
  • Stops nuts and bolts from becoming imbedded in
    soft materials

16
Lock Washers
  • Prevents fastener from loosening
  • Made from spring steel
  • Split and bent, cuts in to base material and
    fastener

17
Multiple Tooth Washer
  • Solid piece
  • Has twisted teeth that dig in to fastener and
    base metal

18
Pins
  • Retains parts in a fixed position
  • Used for alignment

19
Cotter Pins
  • Used to hold nuts in position
  • Specifically Castle nuts

20
Snap Ring
  • Clips in to groves to retain parts
  • Groves can either be external or internal

21
Keys
  • Used to fix gears and pulleys to shafts
  • Cut in gear or pulley called the key seat
  • Cut in shaft called the key way

22
Adhesives
  • Liquid or semi-liquid
  • Prevents loosening
  • Only one drip
  • Range from light to strong

23
Sealants
  • Resistance from the elements
  • Oil, water, gas, grease, and salt
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