5. analysis of spur gear cutting using milling

International Journal For Technological Research In Engineering
Volume 3, Issue 6, February-2016 ISSN (Online): 2347 - 4718
www.ijtre.com Copyright 2015.All rights reserved. 1225
ANALYSIS OF SPUR GEAR CUTTING USING MILLING
MACHINE
Sagar1
, Mr. Neeraj Kumar2
, Mr. Jagbir Sharma3
1
Student of M.E, 2
Assistant Professor, 3
Workshop in charge
Mechanical Dept., Panchkula Engineering College, Haryana.
ABSTRACT: Spur gears are the simplest type of the gear.
Spur gears have teeth parallel to the axis of the wheel. Spur
gears are the most commonly used for the transmission of
power. The most common method of cutting the spur gears
on milling machine is by form cutting. This is done by
taking a blank gear and rotating a cutter, with the desired
tooth pattern, around its periphery. This ensures that the
gear will fit when the operation is finished. While cutting
the spur gears using the milling machine, the analysis of
spur gear is very important. While analysis various
parameter like pressure angle, cutting speed, feed rate,
production time, tooth form, size of the teeth, pitch circle
diameter, depth of cut and outside diameter. All the aspects
are being calculated which is important while making the
spur gears. Spur gears are cutting on milling machine
utilized the various tooth cutters. The no of tooth cutters
can be determined by the tooth count of the gear to be cut
and also analysis the stress concentration in the spur gear
while cutting.
Keywords: Spur gear, milling machine, cutting tool, cutting
speed
I. INTRODUCTION
Gears are used for a wide range of industrial application.
Gears used in aviation industries, textile looms, automobile,
industrial machine, geared motors, agricultural machinery
etc. To meet the service conditions the geared should have
robust construction, reliable performance, high efficiency,
economy and long life. The gear should be fatigue free and
free from all stresses to avoid their failures. The gears should
be free from noise, chatter and should ensure high load
varying capacity at constant velocity ratio. Spur gears are the
mostly used in all type of gear. It is used for the transmitting
of power between two parallel shafts. In this type of gear, the
teeth cut on the cylindrical face are parallel to the axis of the
gear. In milling, a multi-toothed cutter, rotating at a fixed
position on the machine, shapes the work as it is traversed
across the cutter. The work is firmly secured on the machine
table which can be adjusted to set the depth of cut and can be
moves directions in the horizontal plane. In some machines, a
vertical transverse also is possible manufacture of metallic
components using conventional machine tools, cutter tool
wear, its effects on surface finish, and cutter tool failure
provide major limitations to the achievement of economic
production.Form-milling the tooth of involute spur gear
involves specification of the cutting speed for the work piece
material and feed rate of the milling cutter. The speed and
feed rate selection for such cutting has a strong link with the
completion period of the machining exercise, which
indirectly also determines the cost of producing the gears. In
cutting of the gear, most important is that machinability.
Machinability is defined that to cut the material how easily
on a machine to get the desired shape with respect to tooling.
Figure 1 Spur Gear
Form milling is the process of machining special profile
composed of curved and straight lines. It is done with milling
cutter shaped to the profile to be cut.
II. METHOD FOR GEAR CUTTING
Gear cutting on a milling machine, the gear blank is mounted
on a mandrel which is supported between the center of the
dividing head and one more center at the other end. one tooth
space is cut by the milling cutter and a dividing head
/indexing head is used to index the job to the next required
tooth space. The cutter is chosen according to the module (or
DP) and number of teeth of the gear to the cut. This cutter is
mounted on the milling arbor. Before the gear can be cut, it
is necessary to have the cutter centered accurately relative to
the gear holding mandrel. One way is to adjust the machine
table vertically and horizontally until one corner of the cutter
just touches the mandrel on one side. Both the dials are then
set to zero. The table is then adjusted for the cutter to just
touch on the other side of the mandrel with vertical dial
showing zero. The reading of the horizontal feed screw is
read. This reading divided by two gives the central position
of the mandrel relative to the cutter. When the table is set
centrally in this manner it should be locked in that position.
The table is then fed vertically so that the blank just touches
the cutter. The vertical dial is then set to zero. This is
required to give the depth of cut on the job.With these
settings the machine can be started and traversed along the
axis of the job to cut the tooth over the whole width of the
gear. Depth is increased slowly until it reaches the full depth

of the tooth. With the depth setting the backlash of the gear
can be controlled suitably and gear can be manufactured.
Figure 2: Milling Machine
III. PROCEDURE OF GEAR CUTTING
While cutting the gear on a milling machine, it is important
to know how to make the spur gear. One of the most common
ways of making spur gears is by using a dividing head on a
milling machine. The dividing head makes it possible to cut a
gear with almost any number of teeth. It is possible to use
either a horizontal milling machine or a vertical milling
machine. Work piece to be held in dividing head.
A. DIVIDING HEAD
The dividing head is essentially a horizontal shaft with a
worm wheel on it that can be driven round by means of a
worm. The shaft has various means of holding a work piece.
This may seem very similar to a rotary table. It is different in
that there is no table to mount the work piece on. It is
possible to mount a center in the shaft or mount a chuck onto
it. Usually dividing heads are supplied with a tailstock. This
is essential when using a center with the dividing head. It can
also be very useful for supporting the workpiece when using
the chuck. On all dividing heads the worm is turned by
means of a handle. Each turn of the handle can be divided by
means of a dividing plate that contains a number of rings
each with a different number of holes in it. The handle has a
pin that can be moved to fit the holes in any one of the rings
of holes. Dividing heads are designed to divide the circle.
They are not designed to turn by so many degrees though this
can be done.
Figure 3: Dividing Head
B. Indexing Plate:
Dividing plate is the most important part of the dividing
head. The major role of the dividing plate is to key the
dividing circle. The plate contains no of rings of holes. This
means that one turn of the handle can be divided into the
number of holes in the particular ring. Dividing plate having
no of holes on the half of plate drilled on one side and other
side to be drilled.The dividing plate is fitted properly all of
the “zero” holes will be in line and will be vertically above
the shaft of the handle. Usually, next to each of the zero
holes, is stamped the number of holes in the ring
Figure 4: Indexing Plate
C. Holding the work piece:
Work piece can be held in a chuck using with the help of
dividing head. Whereas on a lathe if a chuck holds the
workpiece slightly off center it is often still possible to turn
all the required surfaces so they are concentric to each other.
This is not relevant when milling. If the workpiece has to be
aligned accurately then it either has to be held between
centers or centered accurately using a four-jaw chuck. Most
home machinists do not have horizontal milling machines
but have a vertical one. In this case the gear cutter is held on
a stub arbor held in the vertical spindle’s socket. In this case,
the cutter cuts into the workpiece in the middle of the front
side. The cutters for gear cutting are designed for use on a
horizontal arbor. If a vertical milling machine is being used
then the same cutter is used but it is mounted on a stub arbor.
This is then fitted to the vertical head. High speed cutter cut
the material and makes the teeth on the material and soluble
oil use for the Cooling of cutter and removes the dissipated
heat.
IV. CUTTER OF CUTTING SPUR GEAR
A cutter that was made for a tooth size would make any gear
with that size tooth. But, unfortunately, for any given size of
tooth, pressure angle etc. the shape of the tooth will vary
depending upon the number of teeth on the gear being made.
This means that to be able to cut a gear with any number of
teeth but for a given size of tooth a set of eight cutters is
required. In order to cope with this it is necessary to have a
cutter for each of a range of teeth numbers.

Figure 5: High Speed Cutter
V. SPUR GEAR PARAMETER
There are still a few key features of gear we need and have to
be defined. For gear of size having 28 teeth to mesh properly
with the other gear. There are several conditions that must be
fulfilled:
A. No of Teeth
The number of teeth is important since this determines the
gearing obtained with other gear of this or other numbers of
teeth. Spur gear made on a milling machine having 28 teeth
in proper manner so that they can mesh withanother gear
without rubbing and do not create wear and friction and work
properly.
B. Pitch Circle Diameter
Though a gear has an outside diameter this is not as
important as the pitch circle diameter. This is the distance
between the two centers of two identical gears meshed
together. It is roughly the distance from the middle of a tooth
on one side of the gear to the middle of a tooth on the other
side.
C. Outside Diameter
The gear will have an outside diameter. This is the size the
blank has to be turned down to. Since gears are usually
defined by their tooth size and the number of teeth these set
the outside diameter.
Outside diameter = (no of teeth +2)/ module
D. Depth of Cut
The depth the cutter needs to cut is always marked upon the
gear cutter. It includes an allowance of 10% at the bottom of
the cut so the top of one lot of teeth will not clash with the
bottoms of the other gear
E. Pressure Angle
Where two gears touch each other the angle relative to a
normal on the pitch circle diameter to the tooth face at this
point can vary. In the past the fashion was for a pressure
angle of 14.5º. The current fashion is for 20º. For special
applications this can be even higher.
VI. MATHEMATICAL FORMULAE’S AND TABLE
 PCD = module * no of teeth
 Diametric Pitch = no of teeth / pitch circle diameter
 Circular pitch = (pi * pitch circle diameter) / no of
teeth.
 Outside diameter =(no of teeth +2)/ module
 Cutting Speed= (pi * Diameter * spindle speed) /
1000.
 Feed = spindle speed * feed per tooth * no of flutes
 Indexing Movement = 40 / no of teeth
Observation Reading
No of teeth 28 teeth
Module 2.5
Pitch circle diameter 70mm
Pressure angle 20 deg.
Material Mild Steel
Outside Diameter 75 mm
Indexing Movement 1.428
Working depth mm
circular Pitch 0.7837mm
VII. CONCLUSION
In present work steps involved in manufacturing engineering
of gear teeth have been explained using steps like alignment
of mandrel on which work piece or job to be held, Work
piece size, cutter, center mark on job and teeth profile
generation. According to the manufacturing of the spur gear
various kind of parameter have been calculated. These
parameter help the fresher and new student how to cut the
spur gear on the milling machine using form cutting
technique. Various doubts are being easily solved. In this
paper, analysis that time taken for cutting spur gear tooth
reduces with increase in the cutting speed and feed rate
respectively.
REFERENCES
[1] Khurmi. R. S and Gupta. J. B, a textbook of
machine design, 14th
edition, India: Eurasia
Publishing house limited, 2014.
[2] Oladejo, K.A. and Oriolovo, K.T.,” Analysis of
Gear Milling at various speed, time and feed rate”,
Nigerian Journal of technology (NIJOTECH),
vol.34, No.1, January 2015, pp.150-155.
[3] Kumar. A, Jain. P. K and Pathak. P. M.,” Study of
Tooth Wear on Spur Gear Performance Parameters
Using Reverse Engineering”, International
Conference on Production and Mechanical
Engineering (ICPME), Dec 2014,pp. 30-31, 2014
Bangkok, Thailand.
[4] Rech, J. and Moissan, A., “Surface Hardened
Steels”, International Journal Machine Tools and
Manufacture, vol. 43, Issues 5, pp. 543-550, 2007.
[5] Ozel. C,” Research of production times and cutting
of the spur gears by end mill in CNC milling
machine”, International Journal of Advanced
Manufacturing Technology 54(1):pp.203-213 ·
April 2011.
[6] Papaioannou.S.G,” Manufacture of High Precision
Spur Gears with End Milling Cutters”, The
American Society of Engineers, vol.10, pp-359-366,
1988.

[7] Kumar. M. D,” Fabrication of multi milling
process”, international journal of research in
aeronautical and mechanical engineering”, Vol.2
Issue.2, February 2014, Pgs.: 105-111.
Sagar is pursuing Bachelor of Technology from Panchkula
Engineering College Barwala in the Department of
Mechanical Engineering. His research interest includes
designing, manufacturing and production. It is my first
research paper that I published in international level.
Student of Mechanical Engineering
Mr. Neeraj Kumar is working as assistant professor in the
Mechanical Department at Panchkula Engineering College
Haryana.Currently, he is also the Head of the department. He
obtained his M.Tech in the area of thermal engineering from
National Institute of technology Kurukshetra.He has
published several research papers and articles in various
reputed national and international journals and attend various
conferences.
HOD of Mechanical Department
Mr. Jagbir Sharma is working as a workshop in charge in the
Mechanical Department a Panchkula Engineering College
Haryana. He had done ITI form Ambala. He had worked in
various industries having 22 years experience in mechanical
department and also in teaching.
Workshop In charge

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