The presentation gives you information about various manufacturing methods of gears and information about milling machine, milling cutters, & dividing head.

1. Milling & Gear Manufacturing
Contents:
Classification of Milling Machines, construction and working of
column and knee type milling Machines, Milling methods – Up
milling and down milling, milling operations, Gear cutting on milling
machines, Gear Hobbing, gear shaving, gear burnishing, indexing
methods, Numerical on Indexing Methods.

2. Milling Machine
 Definitions:
A milling machine is a machine tool that removes metal as
the work is fed against a rotating multipoint cutter.
OR
It is a machine tool in which rotating multipoint cutter is
used for extracting the material from the work piece.
Feature:
Due to multi point cutting edges with high speed of
rotation, the rate of metal removal i.e. MRR is very high.

3. Classification
of
Milling Machine
1. Column and knee type milling machines
(a) Hand milling machine
(b) Plain milling machine
(c) Universal milling machine
(d) Om-universal milling machine
(e)Vertical milling machine
2. Manufacturing Or Fixed-bed type milling machine
(a) Simplex milling machine.
(b) Duplex milling machine.
(c) Triplex milling machine.
3. Planer milling machine
4. Special types of milling machines
(a) Rotary table milling machine.
(b) Drum milling machine.
(c) Planetary milling machine.
(d) Pantograph, Profiling and tracer controlled machine

4. Column
And Knee
Type Machine
ActualView

5. Column
And Knee
Type Machine
Block Diagram

6. Column
And Knee
Type Machine
Sketch Diagram

7. Construction
of
column and
knee type
milling
machine
Base:
The base of the machine is grey iron casting and serves as a foundation
member for all other parts which rests on it.
Column :
The column is the main supporting frame mounted on the base. It is box-
shaped and houses all the driving mechanism for the spindle and feed table.
Knee:
The knee is a fixed grey iron casting that slides up and down on the vertical
ways of the column face. The adjustment of height is affected by an elevating
screw mounted on the base that also supports the knee.
Column:
On the top of the knee is placed the saddle, which slides on guide ways set
exactly at 90 degrees to the column face. A cross feed screw near the top of
the knee engages a nut on the bottom of the saddle to move it horizontally, by
hand or power, to apply cross-feed.

8. Table :
It rests on guide ways on the saddle and travels longitudinally. The top of the table is finished accurately and
T-slots are provided for clamping the work and other fixtures.
Overhanging arm :
Overhanging arm act as a support for the arbor. It is mounted on the top of the column extends outwards the
column face and works as bearing support for the other end of the arbor.
Spindle :
The spindle of the machine is located in the upper part of the column and receives power from the motor
through belts, gears, and clutches and transmit it to the arbor. The front end of the spindle just projects from
the column face and is provided with a tapered hole into which various cutting tools and arbor may be
inserted.
Arbor :
Arbor is an extension of the machine spindle on which milling cutters are securely mounted and rotated.
These are made with taper shanks for proper alignment with the machine spindles having taper holes at their
nose.

9. Up Milling
&
Down Milling
Principal of up-milling
Principal of up-milling

10. SR.NO UP MILLING (CONVENTIONAL MILLING) DOWN MILLING (CLIMB MILLING)
1 In up milling the cutter rotates against direction of feed. In Down milling, the cutter rotates with direction
of feed.
2 In this, chip width size is zero at initial cut and increase
with feed. It is maximum at the end of feed.
In this cutting process, chip size is maximum at
start of cut and decrease with the feed. It is zero
at the end of feed.
3 In this process, heat is diffuse to the work piece which
causes the change in metal properties.
In down milling most of heat diffuse to the chip
does not change the work piece properties.
4 In up milling, tool wear is more because the tool runs
against the feed.
In this, tool wear is less compare to the up
milling, due to the cutter rotate with the feed.
5 Tool life is low Tool life is high.
6 The cutting chips are carried upward by the tool so known
as up milling.
The chips are carried downward by the tool so
known as down milling.
7 It has less surface finish & high cutting force It has better surface finish.&
low cutting force.

11. Standard
Milling
Cutters
Types of Standard Milling Cutter
Following are the different types of standard milling cutters:
1.Plain milling cutter.
1. Light duty plain milling cutter.
2. Heavy-duty plain milling cutter.
3. Helical plain milling cutter.
2.Side milling cutter
1. Plain side milling cutter.
2. Staggered teeth side milling cutter.
3. Half side milling cutter.
4. Interlocking side milling cutter.
3.Metal slitting saw
1. Plain metal slitting saw
2. Staggered teeth metal slitting saw
Continued……

12. 4.Angle milling cutter
1. Single angle milling cutter
2. Double angle milling cutter
5.Endmill
1. Taper shank end mill
2. A straight shank end mill
3. Shell end mill
6.T-slot milling cutter
7.Woodruff key slot milling cutter
8.Fly cutter
9.Formed cutter
1. Convex cutter
2. Concave milling cutter
3. Corner rounding milling cutter
4. Gear cutter
5. Thread milling cutter
10.Tap and reamer cutter
Standard
Milling
Cutters

13. T-Slot Milling
Cutter.

15. Milling
Machine
Operations
The 15 different types of milling machine operations are as follow:
1. Plain Milling Operation
2. Face Milling Operation
3. Side Milling Operation
4. Straddle Milling Operation
5. Angular Milling Operation
6. Gang Milling Operation
7. Form Milling Operation
8. Profile Milling Operation
9. End Milling Operation
10. Saw Milling Operation
11. Milling Keyways, Grooves and Slot
12. Gear Milling
13. Helical Milling
14. Cam Milling
15. Thread Milling

16. 1) 2) 3)
4)
5)
6)

17. 7) 8) 9)
10) 11) 12)

18. Gear &
Gear Materials
Definition:
Gear is toothed wheel has evenly spaced tooth on its periphery.
Gear Materials:
Metallic material:
A. Ferrous metals (for heavy loads)
1) Cast iron
2) Cast steel
3) Medium and high carbon steel
4) Alloy steel
B. Non ferrous metals (for light loads)
1) Aluminum
2) Bronze
Non metallic materials
1) Wood
2) Plastic
3) Fibre

19. Gear
Manufacturing
Process

20. Gear
Manufacturing
Process
By Machining
The different methods of production of gears by machining operations
are described below:

21. Gear
Hobbing
 Definition:
Gear Hobbing is a process of generating a gear by means
of a cutter, called hob and cuts like a milling cutter.

22. Gear Hobbing
SetUp
Diagram

23. Hobbing Machine actual view Hob Cutters

24. GearShaping
 Definition:
It is method of manufacturing gears using shaping cutter
on the machine.
 It gear generating process.
 Types
1) GEAR SHAPING USING RACK CUTTER
2) GEAR SHAPING USING PINION CUTTER

25. Gear shaping
Block and
Actual
diagram

26. Gear shaping
using
pinion cutter

27. Gear shaping
using
rack cutter

28. SR.
No.
Gear Shaping Gear Hobbing
1 It is generating process where the shaper is virtually
a gear provided with the cutting edges and the gear
tooth space is formed by one complete another
tooth is reproduced in gear profile.
It is continuous generating process in which the
tooth flanks of the constantly moving work
piece are formed by equally spaced cutting
edges of the hob.
2 It is not a versatile process, only certain types of
components can be produced especially internal
gears can be produced and even racks.
It is versatile process which convers the variety
of work which includes spur gear , helical gears,
worm gears and worm wheels.
3 The indexing for the next tooth has to be done
causing some errors.
The indexing is continuous and there is no
intermittent motion to give rise to errors.
4 Due to the reciprocating action of the cutter there is
no cutting or return stroke in a gear shaper resulting
in a waste.
There is no loss of time due to non cutting on
the return of stroke.
5 It is most suitable for generating internal gears. It is also possible to generate internal gears, but
the application is very limited.

29. Gear
Finishing
Methods
 For smooth running, good performance and long service life, the
gears need finishing of the gear teeth to achieve -
 To be accurate in dimensions and forms
 To have high surface finish and
 To be hard and wear resistive at their tooth flanks
 Common methods of gear finishing are:
1. Gear shaving
2. Gear rolling or burnishing
3. Gear Grinding
4. Gear lapping
5. Gear honing
6. Roll finishing

30. GearShaving
 Definition:
Gear shaving is a free-cutting gear finishing operation which
removes small amounts of metal from the working surfaces of
the gear teeth.

31. Gear
Burnishing
OR
Gear Rolling
It is similar to gear rolling process.
It is also a cold process for finishing the gear teeth and is
employed on gears after cutting but prior to hardening.
The gear is mounted on a vertical reciprocating shaft in
mesh with three hardened and ground burnishing gears.
These gears are power driven. The three gears are fed into
the cut gear and rotated through a few turns in both
directions.

32. Gear
Burnishing
OR
Gear Rolling
1) 2)

33. Index Head
OR
Dividing Head
 Definition:
The function dividing the periphery of gear blank as per
number of teeth required an indexing (rotating the job) after
each tooth cutting is done by special attachment called a
diving head or indexing head.
Types:
1. Plain or simple dividing head
2. Universal dividing head
3. Helical dividing head
4. Optical dividing head

34. Simple
OR
Plain Dividing
Head

35. Universal
Dividing
Head
Universal Dividing Head:

36. Construction
And
Working of
Universal
Dividing Head
 Universal Dividing Head/Indexing Head consists of a robust
body and a worm drive is enclosed in it. It is having a worm
and worm wheel as shown in fig.
 In this, the dividing head spindle carries a worm wheel that
meshes with the worm.
 This worm carries a crank at its outer end. The index pin works
inside the spring-loaded plunger, which can slide radially along
a slot provided in the crank.
 This plunger can slide, adjust the pin position along a desired
hole circle on the index plate.
 The index plate is mounted on the same spindle as the crank,
but on a sleeve, hence the crank and worm spindle can move
independently on the index plate.
 To set a definite distance along the desired hole circle, sector
arms are used. Sector arms are of a detachable type and can be
set at the desired angles with one another. The index plates are
available in a set of two or three, with a number of hole circles
generally on both sides.

37. Indexing
Definition:
It is the operation of dividing the periphery of a work piece into any
number of equal parts.
OR
It is the operation which rotate the work piece through a certain
number of degrees for the purpose of dividing the part.
Methods of indexing :
a) Direct Or Rapid indexing
b) Simple indexing
c) Compound indexing
d) Angular indexing

38. Formulae
1) Direct or Rapid Indexing:
Index Movement(No. of holes to be moved) = 24/N
2) Plain Or simple Indexing:
Index Crank Movement = 40/N
N= No. of divisions required on work
Index Plate 1: 15,16,17,18,19,20
Index Plate 2: 21,23,27,29,31,33
Index Plate 3: 37,39,41,43,47,49
3) Compound Indexing:
Index Crank Movement = 40/N= n1 / N1 +n2 / N2
For problems refer books…..