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INTRODUCTION
Surface roughness has become the most significanttechnical requirement and it is an index of product quality. Inorder to improve the mechanical properties like :-
Fatigue strength
Corrosion resistanceA reasonably good surface finish is desired. Nowadays,the manufacturing industries specially are focusing theirattention on dimensional accuracy and surface finish. In orderto obtain optimal cutting parameters to achieve the best
possible surface finish, manufacturing industries have resortedto the use of handbook based information and operatorsexperience. This traditional practice leads to improper surfacefinish and decrease in the productivity due to sub-optimal useof machining capability.
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OPERATION
Turning operations
Turning is the removal of metal from the outer
diameter of a rotating cylindrical work piece. Turningis used to reduce the diameter of the work piece,
usually to a specified dimension, and to produce a
smooth finish on the metal.
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Turning is the most commonly used method
for metal cutting. Turning operations are
evaluated based on the performance
characteristics such as :-
Surface Roughness
Material Removal Rate
Tool Wear
Tool life
Cutting force.
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PARAMETER
These performance characteristics are strongly
correlated with cutting parameter such as :-
Cutting Speed
Feed Rate
Depth of cut.It is an important task to select cutting
parameter for achieving high cutting performance.
There is need to operate this machines are efficiently as
possible in order to obtained required payback.
Achieving desire surface quality is of great importance
for the functional behavior of the mechanical parts.
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Adjustable Parameters in Turning
Operation
In turning operation a piece of material
(wood, metal, plastic, or stone) is rotated and
a cutting tool is traversed along 2 axes of
motion to produce precise diameters and
depths. Turning can be either on the outside
of the cylinder or on the inside (also known as
boring) to produce tubular components tovarious geometries.
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The turning processes are typically
carried out on a lathe, considered to be theoldest machine tools, and can be of four
different types such as :-
Straight Turning Taper Turning
Profiling or External Grooving
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Those types of turning processes can
produce various shapes of materials such as:- Straight
Conical
Curved
Grooved work piece.
Turning is the process whereby a single
point cutting tool is parallel to the surface. Itcan be done manually, in a traditional form oflathe.
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Conventional Lathe:
A lathe is a machine tool used principallyfor shaping pieces of metal, wood, or othermaterials by causing the work piece to be held
and rotated by the lathe while a tool bit isadvanced into the work causing the cuttingaction. Lathes can be divided into three types foreasy identification:
Engine lathe Turret lathe
Special purpose lathes.
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EssentialFeatures of The Lathe
Bed and Ways :- The bed is the base forthe working parts of the lathe. The mainfeature of the bed is the ways which are
formed on the bed's upper surface and whichrun the full length of the lathe. The tailstockand carriage slide on the ways in alignmentwith the headstock. The headstock is normally
permanently bolted at one end (at theoperator's left).
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Headstock:- The headstock carries the headspindle and the mechanism for driving it. In the
belt-driven type headstock, the driving mechanismconsists merely of a cone pulley that drives thespindle.
Tailstock:- The primary purpose of the tailstock
is to hold the dead center to support one end ofthe work being machined between centers.However, it can also be used to hold live centers,tapered shank drills, reamers, and drill chucks. The
tailstock moves on the ways along the length ofthe bed to accommodate work of varying lengths.It can be clamped in the desired position by thetailstock clamping nut.
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EngineLathes.
The engine lathe is intended for generalpurpose lathe work and is the usual lathe foundin the machine shop. The engine lathe may bebench or floor mounted The engine lathe consists
mainly of :- Headstock
Tailstock
Carriage
and a bed upon which the tailstock and
carriage move.
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Most engine lathes are back-geared and
high torque, which is required for machining
large diameter work pieces and taking heavy
cuts. The usual engine lathe has longitudinal
power and cross feeds for moving the
carriage. It has a lead screw with gears to
provide various controlled feeds for cutting
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Bench-Type Engine Lathe
The bench-type engine lathe is the most
common general purpose screw cutting lathe
normally found in a small shop. It commonly
has an 8 to 12 inch swing and a 3 to 5 foot bed
length, the size being limited by the
practicality of bench mounting. The bench
upon which the lathe is mounted may be astandard wood-topped shop bench or a
special metal lathe
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Carriage:- The carriage carries the crossfeed slide and the compound rest which in
turn carries the cutting tool in the tool post.
The carriage slides on the ways along the bed.
Apron:- The apron is attached to the front
of the carriage. It contains the mechanism
that controls the movement of the carriage for
longitudinal feed and thread cutting. It
controls the lateral movement of the cross-
slide.
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Floor-MountedEngine Lathe
The floor-mounted engine lathe or pedestal-typeengine lathe, is inherently more rigid than the bench-type lathe and may have a swing as great as 16 or 20
inches and a bed length as great as 12 feet, with 105inches between centers. The drive motor is located inthe pedestal beneath the lath headstock. A tensionrelease mechanism for loosening the drive belt is
usually provided so that the drive belt may be quickly
changed to different pulley combinations for speedchanges.
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SlidingGap-Type Floor-Mounted
Engine LatheThe sliding gap-type floor-mounted lathe orextension gap lathe contains two lathe beds, thetop bed or sliding bed, and the bottom bed .Thesliding bed mounts the carriage and the tailstock
and can be moved outward, away from theheadstock as desired. By extending the slidingbed, material up to 28 inches in diameter may beswung on this lathe. The sliding bed may also be
extended to accept between centers work piecesthat would not normally fit in a standard lathe ofthe same size.
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DesignofExperiments:
TaguchiMethods
Design of Experiment (DOE) has been
implemented to select manufacturing process
parameters that could result in a better
quality product. The DOE is an effective
approach to optimize the throughput in
various manufacturing-related processes. In
their study, three independent variables,
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each with three levels, had total of (33) = 27
experimental runs. Oftentimes, the optimum
metal cutting process required studying morethan three factors for the cutting parameters.
For example, if a DOE setup considered
four or five independent variables, each withat least three levels, then (34) = 81 runs or
(35) = 243 runs were required in the
experiments.
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Purposeof Study
There were two purposes of this research.
The first was to demonstrate a systematic
procedure of using Taguchi parameter design
in process control of individual lathe
machines. The second was to demonstrate a
use of the Taguchi parameter design in order
to identify the optimum surface roughnessperformance with a particular combination of
cutting parameters in a lathe operation.
Procedure and Steps of Taguchi
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Procedure and Steps of Taguchi
Parameter Design
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Orthogonal arrays have a balanced
property in which every factor setting occurs
the same number of times for every setting of
all other factors in the experiment.
Orthogonal arrays allow researchers or
designers to study many design parameterssimultaneously and can be used to estimate
the effects of each factor independent of the
other factors. Therefore, the informationabout the design parameters can be obtained
with minimum time and resource.
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Selection of Orthogonal Array
There are 18 basic types of standard OrthogonalArrays (OA) in the Taguchi parameter design(Torng, Chou, & Liu,1997). Since four factors werestudied in this research, three levels of each
factor were considered. Therefore, an L18Orthogonal Array (L18 (21 x 37)) was selected forthis study. The layout of this L18 OA is shown infig. Each run will have three data collected.
Therefore, a total of (18*3) = 54 data values werecollected, which were conducted for analysis inthis study.
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Variable factor levels
Controllable
Factors
Level 1 Level 2 Level 3
A: Depth of cut
B: Cutting speed
C: Feed rateD: Tool diameter
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Orthogonal array (L18(21 x 37))
Column No.
Trial No. 1 2 3 4 5 6
1 1 1 1 1 1 1
2 1 1 2 2 2 2
3 1 1 3 3 3 3
4 1 2 1 1 2 2
5 1 2 2 2 3 3
6 1 2 3 3 1 1
7 1 3 1 2 1 3
8 1 3 2 3 2 1
9 1 3 3 1 3 2
10 2 1 1 3 3 2
11 2 1 2 1 1 3
12 2 1 3 2 2 1
13 2 2 1 2 3 1
14 2 2 2 3 1 2
15 2 2 3 1 2 3
16 2 3 1 3 2 3
17 2 3 2 1 3 1
18 2 3 3 2 1 2
R lt T bl
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Result Table
Experimen
t No. 1
2. (A) Depth of
cut (in)
3. (B) Cutting
speed(rpm)
4 .(C)Feed Rate
(ipm)
5. (D)Back Rack
angle(0C)
Surface
Measurment
1 1
2 1
3 1
4 1
5 1
6 1
7 1
8 1
9 1
10 2
11 2
12 213 2
14 2
15 2
16 2
17 2
18 2
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Thank You