Gear manufacturing methods (poly)

1. GEAR
CUTTING
BY
KHATIK T.R.
SPC Sangola, Dis-Solapur

2. GEAR MANUFACTURING METHODS
- CASTING
- FORMING
- STAMPING
- POWER METALLURGY
- EXTRUSION
- PLASTING MOLDING
- ROLLING PROCESS
- MACHINING

3. 1] CASTING
a) Die casting
b) Sand casting
c) Investment casting
2] FORMING
a) Cold Drawing
b) Gear Rolling
3] Machining processes
a. Rotary wheel- milling
b. Rotary thred wheel-hobbing
c. Rotary/Reciprocating tool-
Gear shapping,broaching

4. Universal Gear Dividing Head

5. Types of Dividing Head
1.Plain and simple Dividing Head
2.Universal Dividing Head
3. Helical Dividing Head
4.Optical Dividing Head

6. Indexing Methods
-Definition
-Types of Indexing method
1.Direct Indexing method
2.Plain / simple Indexing method
3.Compound Indexing method
4.Differiantial Indexing method
5.Angular Indexing method

7. 1.Direct Indexing
• Direct Indexing (Rapid Indexing) is the simplest form of
indexing. Used for quick indexing of work piece.
• The direct indexing plate is mounted on the nose of the
dividing head spindle which also carries the work.
• The number of divisions required by direct indexing is
limited by the number of holes/slots in the direct
indexing plate.
• Direct indexing plates are available with 24, 30 and 36
holes or slots. It is possible to index any number of
divisions which is a factor of total holes/slots in the
plate

8. 1.Direct Indexing in Universal Dividing
Head
• To perform this type of indexing, the worm shaft must be
disengaged from the worm gear wheel.
• Since most direct indexing plate have 24 holes, all divisions
which are factors of 24 (24, 12, 8, 6, 4, 3, 2) can be produced
with this plate.
• Indexing data = N  T
• N – No. of holes in Indexing Plate
• T – No. of required divisions
Example: What is the index movement required to mill 8 slots on
a workpiece?
• N  T = 24  8 = 3 (3 holes on a 24 hole circle)

9. 1.Direct Indexing
• Whenever starting to machine the first hole, it
is necessary to make sure that the indexing
pin is in the hole or slot No. Zero or 24 of the
indexing plate.
• After doing the necessary indexing movement,
it is required to clamp the indexing spindle so
that the cutting force will not go onto the
indexing plate and indexing pin.

10. 2.Plain Indexing (or) Simple Indexing
• Used for divisions beyond the range of direct
indexing
• Universal Dividing Head is used for this
• The Indexing plate should be locked with the
body
• Worm and worm gear is to be engaged
• Dividing head is rotated by turning the index
crank and locked at the next indexed hole on
the plate

11. Plain or Simple Indexing
• 40 turns of indexing crank = 1 revolution of index
head spindle
• Index plates with concentric circles of holes:
• Plate: 1 - 15, 16, 17, 18, 19, 20
• Plate: 2 - 21, 23, 27, 29, 31, 33
• Plate: 3 – 37, 39, 41, 43, 47, 49
• Index crank movement = 40/N (N = number of divisions
required)
• For cutting 30 teeth, 40/30 = 1 + 1/3 = 1 + 7/21 (One
complete turn of indexing crank and 7 holes in 21 hole
circle of the index plate)

13. 3.Differential Indexing
• This method is used for divisions that could
not be indexed by simple indexing
• The required division is obtained by
combination of:
– Movement of the index crank similar to simple
indexing
– Simultaneous movement of the index plate when
the crank is turned
• The rotation of the index plate may be in the
same direction or opposite to the crank
rotation

15. Differential Indexing
• Lock pin is disengaged to permit rotation of index
plate
• A sleeve with bevel gear is connected to the index
plate
• The sleeve and the bevel gear are free to rotate
on the worm shaft
• Another bevel gear engages with it and the shaft of that
gear has change gears that mesh with the gear mounted
on the back of the main spindle
• Crank rotates the spindle
• Spindle’s motion is transmitted to index plate through
change gears

16. Rule for Differential Indexing
1. Gear Ratio = Driving gear/Driven gear
(= Gear on the spindle/Gear on the bevel gear shaft)
=(A-N) X 40/A
where:
N = The required number of divisions to be indexed
A = a number nearer to N which can be indexed by plain
indexing (assumed number)
2. Index Crank Movement for each division = 40/A
(Index crank is to be moved by this amount for N number of
times for complete division of the work)

17. Rule for Differential Indexing
3. Number of idlers in the change gears:
If (A-N) is positive, the index plate must rotate in the same
direction as the crank
If (A-N) is negative, the index plate must rotate in the
opposite direction to the crank
To achieve the correct direction of rotation, number of idle
gears is obtained as follows:
A-N Simple gear train Compound gear train
Positive One idler No idler
Negative Two idlers One idler

18. Rule for Differential Indexing
Change gears with following numbers of teeth are
generally supplied:
24, 24, 28, 32, 40, 44, 48, 56, 64, 72, 82, 100
With these gears and the three sets of standard
index plates, it is possible to index any number
from 1 to 382.

19. 5.Angular Indexing
• Angular indexing is the process of dividing the
periphery of a work in angular measurements and
not by the number of divisions.
• Indexing method is similar to plain indexing
• One complete turn of crank will cause the spindle
and the work to rotate through 360/40 = 9◦
• Index crank movement =
Angular displacement in deg/9
Angular displacement in minutes/540
Angular displacement in seconds/32400

20. • Gear shaping (pinion cutter)
• Gear planing (Rack cutter)
• Gear hobbing
Gear generating methods

21. Gear shaping

22. Gear shaping

23. Gear shaping

24. Gear shaping

25. Gear Planing Rack

26. Gear Planing with a rack cutter

27. Gear Planing with a rack cutter

28. Gear Hobbing
 Hobbing is a process of generating a gear using a
rotating tool called “Hob”.
 The hob has helical threads
 The threads have grooves cut parallel to the axis to
provide cutting edges.
 The gear teeth are cut into the workpiece by a series of
cuts made by the hob.
 It is the most widely used gear cutting process for
creating spur and helical gears.

29. Gear Hobbing
• Gear hobbing is a multipoint machining process in which
gear teeth are progressively generated by a series of cuts
with a helical cutting tool (hob).
• Both the hob and the workpiece revolve constantly as the
hob is fed across the face width of the gear blank.
• They rotate in a timed relationship
• A proportional feed rate is maintained between the gear
blank and the hob
• Several teeth are cut on a progressive basis
• It is used for high production runs

30. Hobs

31. Gear Hobbing

32. Gear Hobbing

33. Gear Hobbing

34. Gear Generating comparison

35. Gear Hobbing

36. Gear Hobbing

37. Gear Hobbing

38. Gear Hobbing

39. Gear Hobbing

40. Gear Hobbing

41. Gear Hobbing

42. Vertical Hobbing Machine

43. Vertical Hobbing Machine

44. Various Gear Cutters

45. Gear Shaving

46. Gear Shaving Cutter

47. Gear Grinding

48. Gear Grinding