Screw thread cutting internal

Cutting Internal Thread

1. Mechanical Engineering Technology Topic: Internal Screw Thread Cutting.   Objectives : Students should be able to: Define internal screw thread. State explain the uses of taps Calculate tap size drill. State precautions associated with screw thread cutting.

2. Cutting Internal Threads Internal threads are made by using a tap . Taps are made of Carbon Steel or High Speed Steel (HSS) and are carefully hardened and tempered for long life. Taps are quite brittle and are easily damaged if not handled properly.

3. Internal Threads

4. Taps are usually made in sets of three Taper Tap Second or Intermediate Tap Plug or Bottoming tap

5. TAPER OR FIRST TAP

6. SECOND OR INTERMEDIATE

7. PLUG OR BOTTOMING TAP

8. Tools used for holding Taps Adjustable Tap Wrench

9. Chuck Pattern Tap Wrench

10. How to use wrench and tap together.

11. INTERNAL SCREW THREADS CUTTING STEPS A hole must be drilled. This hole is called Tapping Size Hole. Formula= D-P where D= Major Diameter P= Pitch Example- M10 * 1.5 Tapping Size= 10-1.5 =8.5mm Clamp work securely in a bench vice, level and square. Make clockwise turns to start the threads and anti-clockwise turns to break the chip Oil must be used to lubricate the threads.

12. Care in Tapping Considerable care must be exercised when tapping. Use the tap before the die because the taps are non-adjustable for size, the dies are Start the tap square. Use a cutting solution where necessary.

13. Care in Tapping Cont’d Ensure that a blind hole is drilled deeper than the depth of thread required to allow clearance for chipping. Do not force a tap to cut. Remove the chips as necessary.

14. Internal THREAD HEX NUT 25 M10x1.5

15. True or False Taps are made in sets of 3. Taps are made of high tensile steel. Taps are usually very brittle. Quiz Time

16. Quiz Time Identify the taps shown below  

17. Quiz Time Identify the tap shown below

18. Quiz Time Identify the tap shown below

19. Quiz Time Identify the tool shown below