Indexing is the process of evenly dividing a circular workpiece into spaced divisions. Indexing heads, also called dividing heads, contain an indexing mechanism to accurately control rotation of the spindle and divide the workpiece. There are three types of indexing heads: plain, universal, and optical. The optical head provides the most precision and can measure angles to the second. Indexing methods include simple indexing using a plain head where the plate mounts directly to the spindle, and ratio indexing where the head contains a worm and wheel driven by a crank to divide the workpiece into the desired number of sections.

1. LENDI INSTITUTE OF ENGINEERING
AND TECHNOLOGY
METAL CUTTING AND MACHINE TOOLS
COURSE CODE: C302
REGULATION: R16
3rd BTECH 1st SEM
PREPARED BY :
POLAYYA CHINTADA M.TECH,M.B.A,(PhD)
ASSISTANT PROFESSOR
TOPIC:
INDEXING OF MILLING

2. INDEXING:
Indexing is the process of evenly dividing the circumference of a
circular work piece into equally spaced divisions, such as in cutting gear
teeth, cutting splines, milling grooves in reamers and taps, and spacing
holes on a circle.

3. INDEXING head or dividing head:
The index head of the indexing contains an indexing mechanism which is
used to control the rotation of the index head spindle to space or divide a
work piece accurately.
An indexing head, also known as a dividing head or spiral head
 Indexing heads are usually used on the tables of milling machines, but
may be used on many other machine tools including drill presses, grinders,
and boring machines.
The work piece is held in the indexing head in the same manner as a
metalworking lathe.
A simple indexing mechanism consists of a 40-tooth worm wheel fastened
to the index head spindle, a single-cut worm, a crank for turning the worm
shaft, and an index plate and sector.
Since there are 40 teeth in the worm wheel, one turn of the index crank
causes the worm, and consequently, the index head spindle to make 1/40 of a
turn; so 40 turns of the index crank revolve the spindle one full turn.

4. INDEXING head or dividing head:
 Dividing heads are 3 types
Plain dividing Head
Universal Dividing Head
Optical dividing Head
Optical dividing Head
Optical Dividing Head is a most precision attachment
Used for precision work, and also
used for checking the accuracy of other indexing heads
It is possible to measure or read the angular dimensions up to seconds

5. INDEXING head or dividing head:
PLAINDIVIDINGHEAD:
This type of dividing heads are 2 types
First type carries indexing plate directly mounted
on its plane with no use of worm and worm wheel
It is simple and used In direct Indexing
The indexing plate consist of 12 or 24 equi spaced
slots on its periphery
Job is held between 2 centers like tailstock centre
and dividing head spindle centre
Hand lever is used for locking the spindle position
A lug engages desired slot of the indexing plate
24 slots plate consist of 2,3,4,8,12 and 24 divisions can be obtained
12 slots plate consist of 2,3,4,6 and12 divisions can be obtained

6. INDEXING head or dividing head:
PLAINDIVIDINGHEAD:
Another form plain dividing head is used in simple indexing
method
The front end of the spindle carries carrier and centre rear side
indexing plate
The indexing plate gets movement by through a worm worm
rotating the wheel
Crank can be any desired position to bring the pin in front of the
desired hole
These plates having 3 plates circle holes 16,42 and 60 or 24,30,36

7. INDEXING head or dividing head:
Universal dividingHEAD:
This type of head used for indexing work
Mainly consist of robust body, enclosed in it by worm drive, consist of worm and
worm wheel
The dividing head spindle carries worm wheel
spindle carrying worm,which meshes with worm wheel, carries a crank at outer
wheel
The index pin works inside the spring loaded plunger, the plunger can slides
radially along a slot provided in the crank in order to adjust the pin position
Sector arms are provide on indexing plate in order to adjust desired angle and hole
position
Indexing plates are available in a set of two or three, with no of hole circles on
both sides
On the backside of the dividing head provided a bracket which carries a slot along
its length

8. INDEXING METHODS

9. INDEXING METHODS
SIMPLE INDEXING METHOD
In this indexing plain dividing head is used, the indexing plate directly mounted on spindle rotated by hand.
This indexing also called as rapid indexing, and does not consist of worm and worm wheel
It can be used when the no of divisions to be obtained is such that the no slots on the periphery of the index
plate is a multiple of the former
Indexing Ratio= N/n
N= no of slots on the periphery of the index plate
n= no of divisions required to be obtained
EXAMPLE
To divide the surface into 6 divisions and the dividing head consists of 24 slots on the periphery
Indexing Ratio= N/n=24/6=4
So the index plate is will be required to move through 4 slots after each cut is over
If the dividing head consist of worm and worm wheel set up
Example
To divide the surface into 10 divisions and the dividing head consists of 60hole circle on the periphery
Indexing Ratio= N/n=60/10=6
So the index plate is will be required to move 6 divisions on 60 hole circle

10. Yours:
POLAYYA CHINTADA M.TECH,M.B.A,(PhD)
ASSISTANT PROFESSOR