8/17/2019 16727 Indexing

1/17

Manufacturing Technology

Milling Machine Tools 

8/17/2019 16727 Indexing

2/17

Dividing head/indexing head:

•Important attachment and almost

indispensible.•Main spindle of dividing head drives

w/p be means of chuck.

•Index plate consist of number of

holes with a crank and pin.

•Worm and worm wheel(have 40

teeth's).

•

Indexing is possible by indexingplate which have equi-spaced holes.

•Full rotation of w/p is produced by

40 revolution of index crank. Fig:Indexing head construction

8/17/2019 16727 Indexing

3/17

Index head parts:

•Headstock with index plates

•Headstock change gears

• Universal chuck

•Footstock

•Center rest

8/17/2019 16727 Indexing

4/17

8/17/2019 16727 Indexing

5/17

The index plate used on Cincinnati and Parkinson dividing heads is

Plate 1: Side 1 :24, 25, 28, 30, 34, 37, 38, 39, 41, 42 and 43 holes

Side 2 : 46, 47, 49, 51, 53, 57, 58, 59, 62 and 66 holes

It is possible to get additional plate using Cincinnati to increase indexing capability.

Plate 2: Side 1-34, 46, 79, 93, 109, 123, 139, 153, 167, 181, 197 holes

Side 2-32, 44, 77, 89, 107, 121, 137, 151, 163, 179, 193 holes

Plate 3: Side 1- 26, 42, 73, 87, 103, 119, 133, 149, 161, 175, 191 holes

Side 2- 28, 38, 71, 83, 101, 113, 131, 143, 159, 173, 187 holes

Method of indexing:

1. Simple/ plain indexing

2. Compound indexing

3. Angular indexing

4. Differential indexing

8/17/2019 16727 Indexing

6/17

1. Simple indexing:

• Carried out using any indexing plate in conjunction with worm.

• Most of the job completed using simple indexing

e.g. we want to divide w/p into 6 equal division.

Then, the rotation of index crank=

This means that the index crack should be rotate 6 full rotation followed by 2/3 of a

rotation.

Fraction of rotation can be done using Brown and Sharpe plate.

Plate 1: 10 holes in 15 hole circle; 12 holes in 18 hole circle

Plate 2: 14 holes in 21 hole circle; 18 holes in 27 hole circle, 22 holes in 33 hole

circle.

Plate 3: 26 holes in 39 hole circle.

8/17/2019 16727 Indexing

7/17

8/17/2019 16727 Indexing

8/17

2. Compound indexing

•When index plate is not sufficient to do a given job then compound indexing is

used.

•Done by moving crank and then a further motion is added or subtracted

•E.g. Indexing is done by moving the crank 5 holes in 20 hole circle and then index

plate together with the crank is indexed back by a hole in 15 hole circle.

•Than total indexing will be

i.e.11 holes in 60 hole circle plate

8/17/2019 16727 Indexing

9/17

Let us make 69 divisions of workpiece circumference by compound indexing

1.Factorise 69= 23*3

2. Select two holes circle at random as 23 and 33

3. Factories them as

23= 23*1 and 33=11*3

3. Use formula as

 After simplifying if we get 1/x then using formula as

Find X and Y by trail and error method

X=21 and Y= 11 i.e. move index crank 21 holes forward in 23 hole plate and

then 11 hole backward in 33 hole plate

8/17/2019 16727 Indexing

10/17

8/17/2019 16727 Indexing

11/17

8/17/2019 16727 Indexing

12/17

8/17/2019 16727 Indexing

13/17

3. Angular indexing:

•Sometimes, if it is desired to carry out indexing using the actual angles rather than

equal number along the periphery, then angular indexing would be useful.

•Since 40 revolution of crank equals one full rotation of w/p which means 360

degree, then one revolution of crank is equivalent to 9 degree.

•E.g calculate the indexing for 41 degree.

Solution: indexing required = 41/9=

This is equivalent to 4 full rotation of the crank followed by 10 holes in the 18 hole

circle in plate no 1.

8/17/2019 16727 Indexing

14/17

4. Differential indexing:

•It is automatic way to carry out compound indexing.

•Indexing is possible using gear train to connect index plate to spindle.

•Index plate moves in relation with head stock spindle.

•Index plate can move right or left.

•Dividing head are supplied with standard set of change(12 gears) gears as

24, 24, 28, 32, 40, 44, 48, 56, 64, 72, 86 and 100

Both simple and compounding indexing used for differential indexing

Differential indexing

8/17/2019 16727 Indexing

15/17

e.g. differential indexing of 121 division.

Solution:

Required indexing is not possible i.e 40/121. hence choose nearest possible divisionas 120.

by simple indexing= 40/120=1/3=6/18

Means choose 6 holes in 18 hole circle.

but still we have 1/3 of rotation is required to get 121 division.Select these rotation from gear train as= 1/3=1/3*16/16=16/48=driver/driven

8/17/2019 16727 Indexing

16/17

differential indexing of 97 divisions

Required indexing is not possible i.e 40/97. hence choose nearest possibledivision as 100 so indexing decided is 40/100=2/5= 8/20

The actual indexing decided is 8 holes in 20  –hole circle.But this indexing is less

than what required 40/97

w/p should move one revolution when crank is moved through 97 turns,

 Actual motion generated = 40  – 97x 40/100 = 3x40/100 =6/5

Change gear set = Driver/driven = 6/5=48/40

Idler gear is required.

8/17/2019 16727 Indexing

17/17