ENM208
INTRODUCTION to MACHINING •
ANADOLU UNİVERSITY •
Industrial Engineering Department •
Manufacturing Processes
Introduction To Machining
Machining is the process of removing unwanted
material from a workpiece in the form of chips.
Machining is capable of creating geometric
configurations, tolerances, and surface finishes often
unobtainable by any other manufacturing processes
Machining is the most important of the basic
manufacturing processes.
If the workpiece is metal, the process is often called
Metal Cutting or Metal Removal.
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Manufacturing Processes
Machining and Precision
Because of the increased demand for high quality, precision machining is
becoming common and hence the need for high accuracy measurement systems.
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Manufacturing Processes
Examples of Machined Parts
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Manufacturing Processes
Inputs to Machining Processes
The machining process is complex because it has such
a wide variety of inputs which are listed as follows:
• The machine tool selected to perform the process.
• The cutting tool selected (geometry and material).
• The properties and parameters of the workpiece.
• The cutting parameters selected (cutting speed, feed
rate, and depth of cut).
• The workpiece holding devices or fixtures.
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Types of Machining Operations
Types of Machining Operations
Manufacturing Processes
Turning Operations
Turning is the process of machining external cylindrical and
conical surfaces. The process uses a machine tool called a lathe.
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Manufacturing Processes
Lathe Machine
The Centre Lathe is used to manufacture cylindrical shapes from a range of materials
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Manufacturing Processes
Lathe Machine
Lathe Machine Characteristics
• Swing - maximum diameter that can be
rotated on the lathe.
• Maximum distance between centers
• Power of the lathe engine.
• Rotational speed range.
• Feed Rate range.
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Manufacturing Processes
Lathe Operations
Turning Operations
To produce straight, conical, formed, or grooved
workpieces such as shafts, spindles and pins
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Manufacturing Processes
Lathe Operations
Facing Operations
To produce flat surface at the end of the part, which are
useful for parts that are attached to other components.
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Manufacturing Processes
Lathe Operations
Boring Operations
To enlarge hole or cylindrical cavity made by a previous
process or to produce circular internal grooves
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Manufacturing Processes
Lathe Operations
Parting or Cutting off Operations
To cut a piece from the end of a part
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Manufacturing Processes
Lathe Operations
Drilling
To produce a hole, which may be followed by boring to
improve its accuracy and surface finish
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Manufacturing Processes
Lathe Operations
Threading
To produce external or internal threads
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Manufacturing Processes
Lathe Operations
Knurling Operations
To produce a regularly shaped roughness on cylindrical
surfaces
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Manufacturing Processes
Cutting Tools for Lathe Operations
Single Point Cutting Tools
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Manufacturing Processes
Single Point Cutting Tool Geometry
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Manufacturing Processes
Turning Tool Angles
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Manufacturing Processes
Cutting-Tool Materials
The selection of cutting-tool materials for a particular application is
among the most important factors in machining operations
The cutting tool is subjected to: (a) high temperatures; (b) contact
stresses, and (c) sliding along the tool-chip interface and along the
machined surface.
A cutting tool material must possess the following characteristics:
Hardness, so that the hardness, strength, and wear resistance of the
tool are maintained at the temperature encountered in cutting
operations.
Toughness, so that impact forces on the tool or due to vibration
during machining do not fracture the tool.
Wear resistance, so that an acceptable tool life is obtained before
the tool is indexed or replaced.
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Manufacturing Processes
Cutting-Tool Materials
Various cutting-tool materials with a wide range of
mechanical, physical, and chemical properties are available.
Tool materials are usually divided into the following general categories:
1- Carbon and medium-alloy steels.
2- High-speed steels.
3- Carbides (coated and uncoated).
4- Ceramics.
5- Diamond.
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Manufacturing Processes
Characteristics of Cutting-tool Materials
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Manufacturing Processes
Workholding on a Lathe
You cannot perform accurate work if the workpiece is improperly
mounted. The requirements for proper mounting are as follows:
1- The work center line must be accurately centered along the
axis of the lathe spindle.
2- The work must be held rigidly while being turned.
3- The work must NOT be sprung out of shape by the holding
device.
4- The work must be adequately supported against any deflection
caused by its own weight and against springing caused by the
action of the cutting tool.
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Manufacturing Processes
Workholding on a Lathe
There are four general methods of holding work in the lathe:
(1) between centers,
(2) In a chuck,
(3) on a mandrel, and
(4) on a faceplate.
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Manufacturing Processes
Turning Parameters
1- Cutting Speed (V) is the primary cutting motion, which relates
the velocity of the cutting tool relative to the workpiece. It is generally given
in units of (m/min).
2- Feed (f) is the amount of material removed per revolution or per
pass of the tool over the workpiece. In turning, feed is in millimeter per
revolution (mm/r), and the tool feeds parallel to the rotational axis of the
workpiece.
3- Depth of Cut (d) It is the distance the tool is plunged into the
surface. In turning, it is half the difference between initial and final diameters
given in (mm).
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Manufacturing Processes
Selection of Cutting Speed
Selection of Cutting Speed depends on three factors:
1- Operation Type.
2- Workpiece Material
3- Tool Material
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Manufacturing Processes
Selection of Feed Rate
Selection of Feed Rate depends on three factors:
1- Operation Type.
2- Workpiece Material
3- Tool Material
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Manufacturing Processes
Roughing and Finishing Cuts
In machining the general procedure is to
(a) Perform one or more roughing cuts at low speed,
fast feed rate and large depth of cut (little consideration
of dimensional tolerances and surface finish), and
V
f
d
(b) Follow it with a finishing cut a higher speed, slower
feed rate and smaller depth of cut for a good surface
finish.
V
f
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d
Manufacturing Processes
Summary of Turning Parameters and Formulas
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Manufacturing Processes
Drilling and Related Hole Making Operations
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Manufacturing Processes
Hole Making Processes
Various Types of Drilling and Reaming Operations
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Manufacturing Processes
Drilling Sequence
The Most Accurate holes are produced by the following
sequence of operations:
1- Center drilling.
2- Drilling.
3- Boring, and
4- Reaming.
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Manufacturing Processes
Drilling Operation
Drilling is the process of producing or enlarging a
hole. This is accomplished by rotating the tool and/or
workpiece.
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Manufacturing Processes
Reaming
Reaming
- Enlarging an existing hole with a multiedged tool (reamer) for dimensional accuracy and/or
surface finish
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Manufacturing Processes
Countersinking Operation
Countersinking
- operation for producing a
tapered feature at the end of a hole. Most popular
application is a feature for a flathead screw (82
degrees).
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Manufacturing Processes
Counterboring Operation
Counterboring -
Enlarging of an existing hole at
one end. This enlarged hole is concentric with the
existing hole and is flat at the bottom.
One
application of this process is a feature to set the head
of a bolt below a surface.
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Manufacturing Processes
Center Drilling
Center Drilling – is an operation used to start a hole
at the desired location on a surface or to produce the
hole at the end of a piece of stock so that it may be
mounted between centers in a lathe.
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Manufacturing Processes
Tapping
Tapping
– an operation used to produce internal
thread in workpieces.
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Manufacturing Processes
Drilling Machines
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Manufacturing Processes
Drilling Tools
Most Commonly used
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Manufacturing Processes
Reamer
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Manufacturing Processes
Drilling Parameters
- Given hole diameter, D (mm),
- Given hole length, L (mm),
- Select cutting speed, V (m/min),
- Select feed, f (mm/r),
• Rotational speed,
• Feed speed,
• Machining time,
1000V
N
D
f m  fN
(mm/min)
L
tm 
fm
• Metal removal rate, MRR 
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(rpm)
(min)

4
D 2 fN
(mm3/min)
Manufacturing Processes
Recommended speeds and feeds
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Manufacturing Processes
Workholding in Drilling
Workholding devices for drilling are important to
ensure that the workpiece can be located properly.
•
•
•
•
Vise
Angle plate
Jig
Clamp to table of drill press
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