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008 threading
008 threading
008 threading
008 threading
008 threading
008 threading
008 threading
008 threading
008 threading
008 threading
008 threading
008 threading
008 threading
008 threading
008 threading
008 threading
008 threading
008 threading
008 threading
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008 threading

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Transcript

  • 1. THREAD-CUTTING TOOLS and PROCEDURES
  • 2. HAND TAPS
    • Taps are cutting tools used to cut internal threads.
  • 3. THREAD SYSTEMS Dimensioning Code American National and Unified Screw Thread Classes of fit: 1 – lose fit 2 – medium fit 3 – tight fit
  • 4. THREAD SERIES
    • There are five basic thread series in American National and Unified Screw Thread system. They are:
    • Coarse (UNC)
    • Fine (UNF)
    • Extra Fine (UNEF)
    • Special (UNS) National
    • Pipe Thread (NPT)
  • 5. THREAD SERIES
    • ISO Metric threads have a somewhat different coding system. For example a metric thread would be noted as:
    • M 10 x 1.5 - 6H
    • M indicates a Metric thread.
    • 10 indicates a basic size of 10 millimeters.
    • 1.5 is the pitch in millimeters. Note that the M 10 taps are also available as M 10 x 1.00 - 6H and 10 x 1.25 -6H.
    • 6 identifies the grade of tolerance. Six (6) is commonly used and comparable with class 2 Unified American Standard.
    • The grade of tolerance ranging from 3 to 5 fine, 6 medium tolerances 7-9 are coarse.
    • H means that it is an internal thread with no allowance. Internal threads are defined with capitals, for example G designates a tight allowance.
  • 6. COMMON THREAD STANDARDS
  • 7. TAP DRILL SIZE
    • American National, or Unified Thread
    • TDS = D – (1/N)
    • Where: TDS = tap drill size
    • D = major diameter of tap
    • N = number of threads per inch
    • ISO Metric Thread
    • TDS = major diameter (mm) – pitch (mm)
    Cross-section of tapered hole Major Diameter Minor Diameter Pitch Depth Tap Drill Size
  • 8. SET OF HAND TAPS
    • Taper tap – tapered from the end approximately six threads and used to start a thread easily.
    • Plug tap - tapered for approximately three threads and used to thread a hole going through a work piece.
    • Bottoming tap – not tapered but chamfered at the end for one thread . Used for threading to the bottom of a blind hole.
  • 9. HAND TAP WRENCH
  • 10. DIFFERENT TYPES OF TAP
  • 11. TAPPING A HOLE
    • Before tapping the following should be determined:
    • The proper tap hole has been drilled.
    • The tap has the correct specifications.
    • The tap hole is clean and free of all chips (particularly for blind holes).
    • A suitable cutting fluid has been selected for application during the tapping process.
    • If the thread is too tight, "chase" the threads by running the tap through again until it meets specifications.
  • 12. REMOVING BROKEN TAPS
    • Tap Extractor
    • Made to fit all sizes of taps
  • 13. PROPER CARE OF TAPS
    • Care must be taken not to damage the cutting edges.
    • A chipped tap must never be used. When not in use, taps should be kept clean and stored in a rack .
  • 14. THREADING DIES
    • Threading dies are used to cut external threads on round work.
  • 15. THREADING DIES Solid die Adjustable split die Used for chasing or recutting damaged thread Has an adjustment screw that permits an adjustment over or under the standard depth of the thread. Half dies have the advantage of taking smaller cuts to reach correct size, so the amount of material taken off can be controlled. Half die
  • 16. DIE STOCK
  • 17. USING DIES
    • The work should be chamfered for ease of starting. The work piece must be securely supported and vertical in the vise .
    • Great care must be taken to start the thread true to the axis of the bar.
    • Lubricant should be used. The threads must be cleaned as often as is necessary.
  • 18. TAP AND DIE SET
  • 19. TYPES OF MACHINE SCREWS

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