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3. 3. SCREW THREADSINTRODUCTION  PLAY AN IMPORTANT ROLE IN ENGINEERING INDUSTRY  EASIEST FASTENERS
4. 4. SCREW THREADSDEFINITION A THREAD IS A HELICAL RIDGE OF UNIFORM SECTION THAT LIES ON INSIDE OR OUTSIDE OF A CYLINDER OR CONE CUTTING GROOVES OF EQUAL LENGTH AND EQUAL DEPTH ON EXTERNAL OR INTERNAL SURFACE OF A CYLINDRICAL OR CONE SHAPED JOB ARE CALLED THREAD CUTTING
5. 5. SCREW THREADSELEMENTS  MAJOR DIAMETER  MINOR DIAMETER  PITCH DIAMETER  PITCH
6. 6. SCREW THREADSPITCH ROOT CREST M P M I I ADEPTH N T J O C O R H R D D D I I I A A A THREAD ANGLE
7. 7. SCREW THREADSELEMENTS OF THREAD Angle Crest Flank Pitch Point M P M A I I J T N O C O R H R D D D I I I A A A Root Thread Depth Center Axis Depth Pitch Base of Thread
8. 8. SCREW THREADSELEMENTS  ROOT  CREST  FLANK  THREAD ANGLE
9. 9. SCREW THREADSPITCH ROOT CREST M P M I I ADEPTH N T J O C O R H R D D D I I I A A A THREAD ANGLE
10. 10. ELEMENTS OF SCREW THREADSMAJOR DIAMETER CREST OR OUTSIDE DIAMETER OF EXTERNAL THREAD ROOT DIAMETER OF INTERNAL THREAD MAJOR DIAMETER = CORE DIAMETER + (2 X DEPTH OF THREAD)
11. 11. SCREW THREADSPITCH ROOT CREST M P M I I ADEPTH N T J O C O R H R D D D I I I A A A THREAD ANGLE
12. 12. ELEMENTS OF SCREW THREADSMINOR DIAMETER CORE OR ROOT DIAMETER OF EXTERNAL THREAD CREST DIAMETER OF INTERNAL THREAD MINOR DIAMETER = MAJOR DIAMETER – 2 DEPTH
13. 13. SCREW THREADSELEMENTS OF THREAD Angle Crest Flank Pitch Point M P M A I I J T N O C O R H R D D D I I I A A A Root Thread Depth Center Axis Depth Pitch Base of Thread
14. 14. ELEMENTS OF SCREW THREADSPITCH DIAMETER DIAMETER OF CENTERS OF TWO OPPOSITE THREADS ASSUMED DIAMETER PASSES THROUGH CENTRE OF THREADS PD = MAJOR DIAMETER – DEPTH
15. 15. SCREW THREADSELEMENTS OF THREAD Angle Crest Flank Pitch Point M P M A I I J T N O C O R H R D D D I I I A A A Root Thread Depth Center Axis Depth Pitch Base of Thread
16. 16. ELEMENTS OF SCREW THREADS PITCH DISTANCE BETWEEN CORRESPONDING POINTS OF TWO ADJACENT THREADS MEASURED PARALLEL TO AXIS PITCH = 1 / TPI
17. 17. SCREW THREADSPITCH ROOT CREST M P M I I ADEPTH N T J O C O R H R D D D I I I A A A THREAD ANGLE
18. 18. ELEMENTS OF SCREW THREADS ROOT  BOTTOM PORTION OF THE THREAD WHERE BOTH SIDES MEET CREST  TOP PORTION OF THE THREAD WHERE BOTH SIDES MEET FLANK  STRAIGHT SIDES, WHICH CONNECT THE CREST WITH THE ROOT
19. 19. SCREW THREADSPITCH ROOT CREST M P M I I ADEPTH N T J O C O R H R D D D I I I A A A THREAD ANGLE
20. 20. ELEMENTS OF SCREW THREADS THREAD ANGLE  ANGLE AT WHICH BOTH SIDES OF THE THREAD MEET AXIS OF A SCREW  LONGITUDINAL CENTERLINE THROUGH A SCREW BASE OF THE THREAD  BOTTOM SECTION OF THE THREAD  GREATEST SECTION BETWEEN THE TWO ADJACENT ROOTS
21. 21. SCREW THREADSPITCH ROOT CREST M P M I I ADEPTH N T J O C O R H R D D D I I I A A A THREAD ANGLE
22. 22. SCREW THREADS DEPTH OF THREAD  DISTANCE FROM CREST TO ROOT MEASURED VERTICALLY LEAD  DISTANCE TRAVELED BY A NUT IN ONE COMPLETE REVOLUTION  SINGLE START THREADS : LEAD = PITCH  MULTI START THREADS : LEAD = PITCH X NUMBER OF STARTS
23. 23. SCREW THREADSPITCH ROOT CREST M P M I I ADEPTH N T J O C O R H R D D D I I I A A A THREAD ANGLE
24. 24. SCREW THREADS THREADS PER INCH  NUMBER OF THREADS IN ONE INCH LENGTH OF SCREW. IT IS ABBREVIATED AS TPI. THICKNESS OF THREADS  DISTANCE BETWEEN THE ADJACENT SIDES OF THE THREADS MEASURED ALONG THE PITCH LINE
25. 25. SCREW THREADSPITCH ROOT CREST M P M I I ADEPTH N T J O C O R H R D D D I I I A A A THREAD ANGLE
26. 26. SCREW THREADS DEPTH OF ENGAGEMENT  DEPTH OF THE THREAD CONTACT OF TWO MATING PARTS MEASURED RADIALLY LENGTH OF ENGAGEMENT  LENGTH OF CONTACT BETWEEN TWO MATING PARTS MEASURED AXIALLY.
27. 27. SCREW THREADSCLASSIFICATION  ACCORDING TO POSITION  SHAPE AND WORK  DIRECTION  NUMBER OF STARTS
34. 34. SCREW THREADSWORM AND WORM GEAR
40. 40. SQUARE THREADS  USED IN LIFTING WEIGHT, VICE SPINDLES, PRESS MACHINE SPINDLE, POWER TRANSMISSION AND SCREW JACK ETC  ANGLE = 90°  DEPTH = 0.5 X PITCH  CREST AND ROOT WIDTH = 0.5 X PITCH
44. 44. ACME THREADS ANGLE = 290 DEPTH = 0.5 X P + 0.01 INCH FLAT AT BOTTOM =.3707X P-.0052 FLAT AT TOP =.3707X P
45. 45. ACME THREADS USED FOR POWER TRANSMISSION USED WHERE ENGAGEMENT WITH A HALF NUT IS REQUIRED AS IN LATHE ANGLE = 290 DEPTH = 0.5 X P + 0.001 INCH