A tool that has a single point for cutting purpose is called single point cutting tool. It is generally used in the lathe machine, shaper machine etc. It is used to remove the materials from the workpiece.
A tool that has a single point for cutting purpose is called single point cutting tool. It is generally used in the lathe machine, shaper machine etc. It is used to remove the materials from the workpiece.
Fundamentals of Metal cutting and Machining Processes
MACHINING OPERATIONS AND MACHINING TOOLS
Turning and Related Operations
Drilling and Related Operations
Milling
Machining Centers and Turning Centers
Other Machining Operations
High Speed Machining
This presentation contains various aspects of metal cutting like mechanics of chip formation, single point cutting tool, chip breakers, types of chips,etc
This chapter aims to provide basic backgrounds of different types of machining processes and highlights on an understanding of important parameters which affects machining of metals with their chip removals.
Metal cutting or Machining is the process of producing workpiece by removing unwanted material from a block of metal. in the form of chips. This process is most important since almost all the products get their final shape and size by metal removal. either directly or indirectly.
The major drawback of the process is loss of material in the form of chips. In this chapter. we shall have a fundamental understanding of the basic metal process.
Unit 3A1 Lathe turning and related operationsMechbytes
Coverage of machine tools classification, types, functions and Lathe machine, Turning & related operations, Lathe construction, parts, accessories and attachments
Unit 2 Machinability, Cutting Fluids, Tool Life & Wear, Tool MaterialsMechbytes
Concept of machinability, machinability index, factors affecting machinability
Different mechanism of tool wear types of tool wear (crater, flank etc.), Measurement and control of tool wear
Concept of tool life, Taylor's tool life equation (including modified version)
Different tool materials and their applications including effect of tool coating
Introduction to economics of machining
Cutting fluids: types, properties, selection and application methods
Fundamentals of Metal cutting and Machining Processes
MACHINING OPERATIONS AND MACHINING TOOLS
Turning and Related Operations
Drilling and Related Operations
Milling
Machining Centers and Turning Centers
Other Machining Operations
High Speed Machining
This presentation contains various aspects of metal cutting like mechanics of chip formation, single point cutting tool, chip breakers, types of chips,etc
This chapter aims to provide basic backgrounds of different types of machining processes and highlights on an understanding of important parameters which affects machining of metals with their chip removals.
Metal cutting or Machining is the process of producing workpiece by removing unwanted material from a block of metal. in the form of chips. This process is most important since almost all the products get their final shape and size by metal removal. either directly or indirectly.
The major drawback of the process is loss of material in the form of chips. In this chapter. we shall have a fundamental understanding of the basic metal process.
Unit 3A1 Lathe turning and related operationsMechbytes
Coverage of machine tools classification, types, functions and Lathe machine, Turning & related operations, Lathe construction, parts, accessories and attachments
Unit 2 Machinability, Cutting Fluids, Tool Life & Wear, Tool MaterialsMechbytes
Concept of machinability, machinability index, factors affecting machinability
Different mechanism of tool wear types of tool wear (crater, flank etc.), Measurement and control of tool wear
Concept of tool life, Taylor's tool life equation (including modified version)
Different tool materials and their applications including effect of tool coating
Introduction to economics of machining
Cutting fluids: types, properties, selection and application methods
Traditional machining processes involves the machining processes using machine tool like lathe milling, drilling, milling grainding, shaper, planner machines
Mechanics of chip formation, single point cutting tool, forces in machining, Types of chip, cutting
tools– nomenclature, orthogonal metal cutting, thermal aspects, cutting tool materials, tool wear,
tool life, surface finish, cutting fluids and Machinability
Theory of Metal cutting - Principles of Metal cutting, orthogonal and oblique cutting, Merchant circle diagram, cutting forces, power requirements, Economics of machining,problems
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Student information management system project report ii.pdfKamal Acharya
Our project explains about the student management. This project mainly explains the various actions related to student details. This project shows some ease in adding, editing and deleting the student details. It also provides a less time consuming process for viewing, adding, editing and deleting the marks of the students.
Forklift Classes Overview by Intella PartsIntella Parts
Discover the different forklift classes and their specific applications. Learn how to choose the right forklift for your needs to ensure safety, efficiency, and compliance in your operations.
For more technical information, visit our website https://intellaparts.com
Vaccine management system project report documentation..pdfKamal Acharya
The Division of Vaccine and Immunization is facing increasing difficulty monitoring vaccines and other commodities distribution once they have been distributed from the national stores. With the introduction of new vaccines, more challenges have been anticipated with this additions posing serious threat to the already over strained vaccine supply chain system in Kenya.
COLLEGE BUS MANAGEMENT SYSTEM PROJECT REPORT.pdfKamal Acharya
The College Bus Management system is completely developed by Visual Basic .NET Version. The application is connect with most secured database language MS SQL Server. The application is develop by using best combination of front-end and back-end languages. The application is totally design like flat user interface. This flat user interface is more attractive user interface in 2017. The application is gives more important to the system functionality. The application is to manage the student’s details, driver’s details, bus details, bus route details, bus fees details and more. The application has only one unit for admin. The admin can manage the entire application. The admin can login into the application by using username and password of the admin. The application is develop for big and small colleges. It is more user friendly for non-computer person. Even they can easily learn how to manage the application within hours. The application is more secure by the admin. The system will give an effective output for the VB.Net and SQL Server given as input to the system. The compiled java program given as input to the system, after scanning the program will generate different reports. The application generates the report for users. The admin can view and download the report of the data. The application deliver the excel format reports. Because, excel formatted reports is very easy to understand the income and expense of the college bus. This application is mainly develop for windows operating system users. In 2017, 73% of people enterprises are using windows operating system. So the application will easily install for all the windows operating system users. The application-developed size is very low. The application consumes very low space in disk. Therefore, the user can allocate very minimum local disk space for this application.
Event Management System Vb Net Project Report.pdfKamal Acharya
In present era, the scopes of information technology growing with a very fast .We do not see any are untouched from this industry. The scope of information technology has become wider includes: Business and industry. Household Business, Communication, Education, Entertainment, Science, Medicine, Engineering, Distance Learning, Weather Forecasting. Carrier Searching and so on.
My project named “Event Management System” is software that store and maintained all events coordinated in college. It also helpful to print related reports. My project will help to record the events coordinated by faculties with their Name, Event subject, date & details in an efficient & effective ways.
In my system we have to make a system by which a user can record all events coordinated by a particular faculty. In our proposed system some more featured are added which differs it from the existing system such as security.
Automobile Management System Project Report.pdfKamal Acharya
The proposed project is developed to manage the automobile in the automobile dealer company. The main module in this project is login, automobile management, customer management, sales, complaints and reports. The first module is the login. The automobile showroom owner should login to the project for usage. The username and password are verified and if it is correct, next form opens. If the username and password are not correct, it shows the error message.
When a customer search for a automobile, if the automobile is available, they will be taken to a page that shows the details of the automobile including automobile name, automobile ID, quantity, price etc. “Automobile Management System” is useful for maintaining automobiles, customers effectively and hence helps for establishing good relation between customer and automobile organization. It contains various customized modules for effectively maintaining automobiles and stock information accurately and safely.
When the automobile is sold to the customer, stock will be reduced automatically. When a new purchase is made, stock will be increased automatically. While selecting automobiles for sale, the proposed software will automatically check for total number of available stock of that particular item, if the total stock of that particular item is less than 5, software will notify the user to purchase the particular item.
Also when the user tries to sale items which are not in stock, the system will prompt the user that the stock is not enough. Customers of this system can search for a automobile; can purchase a automobile easily by selecting fast. On the other hand the stock of automobiles can be maintained perfectly by the automobile shop manager overcoming the drawbacks of existing system.
TECHNICAL TRAINING MANUAL GENERAL FAMILIARIZATION COURSEDuvanRamosGarzon1
AIRCRAFT GENERAL
The Single Aisle is the most advanced family aircraft in service today, with fly-by-wire flight controls.
The A318, A319, A320 and A321 are twin-engine subsonic medium range aircraft.
The family offers a choice of engines
Water scarcity is the lack of fresh water resources to meet the standard water demand. There are two type of water scarcity. One is physical. The other is economic water scarcity.
Overview of the fundamental roles in Hydropower generation and the components involved in wider Electrical Engineering.
This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
Collaborators and co editors: Charlie Sims and Connor Healey.
(C) 2024 Robbie E. Sayers
Industrial Training at Shahjalal Fertilizer Company Limited (SFCL)MdTanvirMahtab2
This presentation is about the working procedure of Shahjalal Fertilizer Company Limited (SFCL). A Govt. owned Company of Bangladesh Chemical Industries Corporation under Ministry of Industries.
2. FUNDAMENTALS OF METAL CUTTING
Overview of Machining Technology
Theory of Chip Formation in Metal Machining
Tool geometry
Force Relationships and the Merchant Equation
Factors affecting tool life
Power and Energy Relationships in Machining
Cutting Temperature
Tool inserts Specifications
Cutting fluid
2
4. MANUFACTURING PROCESS
Additive
Manufacturing (AM)
is an appropriate
name to describe the
technologies that
build 3D objects by
adding layer-upon-
layer of material
Subtractive
manufacturing is a
process by which 3D
objects are
constructed by
successively cutting
material away from a
solid block of material.
4
6. A machine tool is a power driven cutting machine which is used for
shaping, sizing or processing a work piece to a product of desired
accuracy by removing excess material from the surface in the form
of metal chips.
e.g. lathe, Shaping machine, planning machine, slotting machine,
milling machine, drilling machine, grinding machine etc.
Machine Tools
6
7. FUNCTIONS OF MACHINE TOOL
Functions of a machine tool are
Holding, supporting and guiding the work piece to be machined.
Holding, supporting and guiding the cutting tool.
Regulating the cutting speed and movement between work piece and
cutting tool.
Providing the required motion to the work piece and cutting tool.
Performing various operations required. 7
8. During machining the cutting tool exerts a compressive
force on the workpiece and when this force exceeds the
yield point, the material starts to deform plastically.
Figure 21.2 - (a) A cross-sectional view of the machining process, (b)
tool with negative rake angle; compare with positive rake angle in (a)
10. ORTHOGONAL CUTTING
2-D cutting process.
Only two components of
cutting force are there
Cutting edge is perpendicular
to the direction of cutting
speed
Chip flows over the face of
tool.(normal to cutting edge)
Max chip thickness occurs at
the middle
Tool is perfectly sharp and
contacts the chip on rake face
only
Only one cutting edge is in
action
Tool life is less
11. OBLIQUE CUTTING
3-D cutting process.
Three components of
cutting forces are there
Cutting edge is at an angle
to the direction of cutting
speed
Chip flows over the face of
tool.(at an angle to cutting
the edge)
Max chip thickness may or
may occurs at the middle
More than one cutting edge
is in action,
Tool life is more
12. CHIP FORMATION
o Unwanted material removed from the workpiece is known
as Chip.
o The basic requirement for the chip formation are
o The tool must be harder than workpiece material
o There must be a relative motion between tool and workpiece
Types of chips
1. Discontinuous chip
2. Continuous chip
3. Continuous chip with Built-up Edge (BUE)
12
13. Ductile work materials (e.g., low
carbon steel)
Small depth of cut, large rake
angle , presents of cutting fluid,
High cutting speed, small feed rate
Chips are in the form of long coil .
Uniform thickness
Sharp cutting edge on the tool
Low tool-chip friction.
Good surface finish.
High tool life.
Less power consumption
Chip disposal is a problem
CONTINUOUS CHIP
13
14. Continuous with BUE
Ductile materials
Small rake angle , low to
medium cutting speed& absence
or insufficient cutting fluid
Chip get welded on to tool /work
surface
High adhesion causes portions of
chip to adhere to rake face
BUE formation is cyclical; it
forms, then breaks off
(c) continuous with built-up
edge
14
15. Discontinuous chip
Brittle work materials (e.g., cast
iron,bronze,)
Low cutting speed, and no
coolant.
Small rake angles
Large feed and depth of cut
High tool-chip friction
This chip can be easily handled
15
17. VARIABLES INFLUENCING CHIP FORMATION
Mechanical properties of material to be cut
Depth of cut
Cutting speed
Feed rate
Type of cutting fluid
Machining temperature at cutting region
Coefficient of friction between chip and tool
17
18. CUTTING TOOL CLASSIFICATION
1. Single-Point Tools
One cutting edge
Turning uses single point tools
Point is usually rounded to form a nose radius
2. Multiple Cutting Edge Tools
More than one cutting edge
Motion relative to work usually achieved by
rotating
Drilling and milling use rotating multiple cutting
edge tools.
18
19. Figure 21.4 - (a) A single-point tool showing rake face, flank, and tool
point; and (b) a helical milling cutter, representative of tools with
multiple cutting edges
19
20. PARTS OF SINGLE POINT CUTTING TOOL
Shank
it is the body of the tool, on one
end of which cutting point is
formed
Face
The surface over which the
chip impinges as it is removed
from workpiece
Flank
The surface of the tool which is
facing the work piece
20
21. Base
Bottom surface of shank.
Nose
It is the curve formed by
joining the side cutting
edge and end cutting edge.
Cutting edge
The portion of the face edge
along which the chip is
separated from the work
21
23. TOOL GEOMETRY
Back rake angle:
It is the angle b/w the face of
the tool and the line parallel to
the base of the tool
Measured in a plane parallel
to the centre line of point
and right angles to the base.
+ve = face slopes downward
-ve = face slopes upward.
It controls the formation of
chip and guides its direction
of flow
23
24. Side rake angle:
It is the angle b/w the tool face and line parallel to
the base of the tool
Measured in a plane perpendicular both the centre
line of point and the base.
6-15⁰
It also controls the direction of chip flow
24
25. Relief Angle:
It is the angle b/w a plane perpendicular to the base
of a tool and the flank immediately adjacent to cutting
edge.
It controls the rubbing at tool-workpiece interface.
Higher the relief angle ,the tool may be chip-off
Smaller the relief angle, greater will be the flank wear.
(a) side relief angle
(b) end relief angle
Side relief angle
Angle b/w the portion of the flank immediately below
the cutting edge and a line drawn through the cutting
edge/point .
25
26. End relief angle
Angle b/w the portion of the end flank immediately
below the cutting edge and a line drawn through the
that cutting edge perpendicular to base.
8-15⁰
26
27. Clearance (cutting)angle
o Angle between a plane perpendicular to the base of a
tool and that of flank immediately adjacent to the
base.
End clearance angle
Angle between a plane perpendicular to the base of a
tool and that of end flank(surface below the end
cutting edge) immediately adjacent to the base
Side clearance angle
Angle between a plane perpendicular to the base of a
tool and that of side flank(surface below the cutting
edge) immediately adjacent to the base
27
28. Nose radius
It is the curve formed by joining side cutting edge and
the end cutting edge.
Larger the nose radius, greater will be the surface
finish.
28
29. TOOL SIGNATURE
Tool angles have been standardized by the American
Standard Association (ASA)
Tool angles given in a definite pattern
Back rake angle-
Side rake angle-
End relief angle
Side relief angle-
End cutting edge angle 8
Side cutting edge angle
Nose radius – 0.8 mm
29
30. PROBLEM
A tool having 8, 8, 5, 5, 6, 6, and 1 as signature
in ASA system will have the following angles.
30
31. MACHINABILITY
MT
Machinability is the easiness with which a material can
be machined satisfactorily.
Good machinability refers to removal of material with
moderate cutting forces.
Variables affecting machinability are
Work variable
Tool variable
Machine variable
Cutting conditions
32. 32
Work variables
Chemical composition
Micro structure
Mechanical Properties
Physical properties
Method of manufacturing
Tool variables Tool geometry
Nature of cutting
Rigidity of tool
33. 33
Machine variables
Rigidity of machine
Power and accuracy of M T
o Cutting conditions
o Cutting speed has greatest influence on tool life and
machinability.
ADVANTAGES
• Good surface finish
• High cutting speed
• Less power consumption
• High MRR
• Less tool wear
36. FLANK WEAR
This is also called edge wear.
Friction/abrasion/adhesion, b/w tool & workpiece are
the main causes of flank wear.
It is the flat worn out portion on flank, and called
wear land.
Flank wear takes place when machining brittle
materials like cast iron.
It also occurs when the feed is less than
0.15mm/revolution.
As the flank wear increases, the temperature at
tool/workpiece also increases.
Due to this the hardness of the tool decreases and it
fails. 36
38. CREATER WEAR
It occurs at face of the tool.
As chip slides over the face of the tool, it worn out
gradually.
The cavity formed on the face of the tool is known as
creater wear.
As the creater become large, the cutting edge may
break from tool.
It occurs when machining ductile material.
38
39. 39
a) Features of tool wear in a turning operation. VB: indicates average flank
wear
b) – e)
Examples of
wear in
cutting tools
b)
Flank
wear
c)
Crater
wear
d)
Thermal
cracking
e) Flank
wear and
built-up
edge (BUE)
40. FACTORS INFLUENCING CRATER WEAR
40
1. Temperature at the tool–chip interface
2. Chemical affinity between tool and workpiece
materials
Crater wear occurs due to “diffusion mechanism”
This is the movement of atoms across tool-chip interface
Since diffusion rate increases with increasing
temperature, ⇒ crater wear increases as temperature
increases
Note how quickly crater wear-rate
increases in a small temperature
range
Coatings to tools is an effective
way to slow down diffusion process
(e.g. titanium nitride, alum. oxide)
41. OTHER TYPES OF WEAR
41
Nose wear is the rounding of a sharp tool due to
mechanical and thermal effects
It dulls the tool, affects chip formation, and causes rubbing of
the tool over the work piece
This raises tool temperature, which causes residual stresses
on machined surface
Tools also may undergo plastic deformation because
of temperature rises in the cutting zone
Thermal cracking happens due to elevated temperature
at tool work piece interface.
42. CHIPPING, AND FRACTURE
42
Tools may undergo chipping, where small fragment
from the cutting edge of the tool breaks away
Mostly occurs with brittle tool materials (e.g. ceramics)
Small fragments: “microchipping” or “macrochipping”
Large fragments: “gross fracture” or “catastrophic failure”
Chipping may occur in a region of the tool where a
small crack already exists
This causes sudden loss of tool material, change in tool shape
⇒ drastic effects on surface finish, dimensional accuracy
Two main causes of chipping
Mechanical shock (impact due to interrupted cutting)
Thermal fatigue (variations in temp. due to interrupted
cutting)
43. 43
It is very important to continuously monitor the
condition of the cutting tool to observe wear, chipping,
gross failure
Classified into 2 categories:
1. Direct method
2. Indirect methods
WEAR MEASUREMENT
44. 44
1. Direct method for observing the condition of a cutting tool
involves optical measurements of wear
e.g. periodic observation of changes in tool using tool maker’s
microscope
e.g. programming tool to touch a sensor after every machining cycle
(to detect broken tools)
45. 45
2. Indirect methods of observing tool conditions involve the
correlation of the tool condition with certain parameters
Parameters include forces, power, temp. rise, surface finish,
vibration, chatter
e.g. transducers which correlate acoustic emissions (from stress
waves in cutting) to tool wear and chipping
e.g. transducers which continually monitor torque and forces
during cutting, plus measure and compensate for tool wear
e.g. sensors which measure temperature during machining
46. FACTORS AFFECTING TOOL LIFE
The life of the cutting tool is affected by
Cutting speed
Feed & depth of cut
Tool geometry
Tool material
Cutting fluid
Work material
Rigidity of work, tool, and machine
46
47. CUTTING SPEED
When cutting speed increases, the tool life
decreases because cutting speed has greater
influence on the MRR and thereby tool life.
when cutting speed increases the tool/workpiece
interface temperature will also increase and as a
result hardness of tool decreases.
The relation b/w cutting speed and tool life in
terms of Taylor’s formula
47
49. FEED AND DEPTH OF CUT
The life of the cutting tool is influenced by the
amount of metal removed by the tool per minute
The effect of feed and depth of cut on tool life is
given by
V= 257 / (T^0.19*f^0.36*t^0.8) m/min
V= cutting speed
T= tool life
f = feed in mm/min
t = depth of cut in mm
49
50. TOOL MATERIAL
An ideal tool is one which remove max volume of
material at all cutting speed
Mechanical , Physical and chemical properties of tool
material will influence tool life
Carbide tools have more life than high speed steel.
50
51. CUTTING FLUID
Heat produced during metal cutting is carried away
from the tool and work by means of cutting fluid
Cutting fluid reduces friction at chip tool interface and
increases tool life.
Cutting tool which directly control the amount of heat
at the chip tool interface is given by the formula
TӨ^n= C
T= tool life
Ө = temp @chip tool interface
n= index which depends upon the shape and material
of the cutting tool.
51
52. WORK PIECE MATERIAL
Tool life also depends on the micro structure of the
work piece material.
Tool life will be more when machining soft metals
than hard metals like cast iron and alloy steel.
52
53. RIGIDITY OF WORK , TOOL , AND MACHINE
A strongly supported tool on a rigid machine will
have more life than tool machining under
vibrating machine.
loose work piece will decrease the tool life.
53
54. FORCES ON A SINGLE POINT CUTTING TOOL
Work material offers resistance during machining.
This resistance is overcome by cutting force applied to tool
face/ point.
Work done by this force causes the deformation of the
metal in the form of chip.
Magnitude of this cutting force depends upon
Material being machined
Feed rate
Depth of cut
Tool geometry
Cutting speed
Coolant used
54
55. MEASUREMENT OF CUTTING FORCES
DIRECT METHOD
Mechanical dial gauges
Strain gauge dynamometer
Pneumatic and Hydraulic dynamometers
Electrical Dynamometers
Piezo-electrical dynamometers
INDIRECT METHODS
With the aid of watt meter
By measuring variation of voltage & current consumption during
machining.
55
56. NEED FOR CUTTING FORCE DETERMINATION
Determination of power consumption.
Selection of motor.
Structural design of Machine.
Maximize productivity
56
60. MERCHANT’S CIRCLE
Introduced by Earnst Merchant.
This theory assumes that the cutting is orthogonal and
shear angle is located where the energy required for the
deformation is minimum, also the workdone is
minimum.
This is known as the minimum energy theory
60
61. MERCHANT’S CIRCLE DIAGRAM
The following is a circle diagram Known as Merchant’s
circle diagram, which is convenient to determine the
relation between the various forces and angles.
61
62. In the diagram two force triangles have been combined
and R and R’ together have been replaced by R. the force
R can be resolved into two components Fc and Ft.
Fc and Ft can be determined by force dynamometers
The rake angle (α) can be measured from the tool, and
forces F and N can then be determined. The shear angle
(φ) can be obtained from it’s relation with chip reduction
coefficient.
Now Fs & Fn can also be determined
62
63. ASSUMPTIONS
Work moves with uniform velocity.
The shear is occurring in a plane.
The tool is perfectly sharp and no contact along clearance
face.
The cutting edge is a straight line.
Width of tool is greater than width of work piece
Stress on the shear plane is uniformly distributed.
Uncut chip thickness is constant.
Continuous chip is produced with no built up edge.
The chip does not flow to either side.
63
64. THE PROCEDURE TO CONSTRUCT A MERCHANT’S
CIRCLE DIAGRAM
Set up x-y axis labeled with forces, and the origin in
the centre of the page. The cutting force (Fc) is drawn
horizontally, and the tangential force (Ft) is drawn
vertically. (Draw in the resultant (R) of Fc and Ft
64
Ft
U
M
Fc
L
65. 65
R
Locate the centre of R, and draw a circle that encloses
vector r. if done correctly, the heads and tails of all 3
vectors will lie on this circle
R
66. Draw in the cutting tool in the upper right hand
quadrant, taking care to draw the correct rake angle
(α) from the vertical axis.
66
α
67. Draw the cutting tool in the upper right hand quadrant,
taking care to draw the correct rake angle (α) from the
vertical axis
67
F
P
68. A line can now be drawn from the head of the friction vector,
to the head of the resultant vector (R). This gives the normal
vector (N). Also add a friction angle (β) between vectors R and
N. Therefore, mathematically, R = Fc +Ft= F +N.
68
N
β
69. Draw a feed thickness line parallel to the horizontal axis.
Next draw a chip thickness line parallel to the tool
cutting face
69
Feed thickness line
Chip thickness line
α
φ
S
αFs
70. Draw a vector from the origin (tool point) towards the
intersection of the two chip lines, stopping at the circle.
The result will be a shear force vector (Fs). Also measure
the shear force angle between Fs and Fc
70
Fn
71. Finally add the shear force normal (Fn) from the head
of Fs to the head of R.
Use a scale and protractor to measure off all distances
(forces) and angles.
71
U
α
L
W
Β-α
φ
90- α
90- β
z
84. ADVANTAGES OF MERCHANT’S CIRCLE
DIAGRAM
Easy , quick and reasonably accurate
determination of several other forces from a few
known forces involved in machining.
Friction at chip tool interface and dynamic yield
shear strength can be easily determined.
Equation relating the different forces can be
easily developed
84
85. LIMITATIONS OF MCD
MCD is valid only for orthogonal cutting
By the ratio F/N, the MCD gives apparent (not
real)coefficient of friction.
It is based on single shear plane theory.
85
86. ECONOMIC OF MACHINING
It is used to obtain lowest possible unit cost and highest
possible production rate for any given operation.
At highest cutting speed , the tool cost may increase owing
to shorter tool life , and the tool cost per unit piece decrease.
COST PER PIECE = IDLE COST PER PIECE+TOOL
CHANGING COST PER PIECE+ + CUTTING COST PER
PIECE
86
87. CUTTING COST PER
PIECE.
Cutting cost per
piece depends on the
time , the tool
actually cut the
workpiece
It can be reduced by
increasing MRR
87
88. IDLE COST PER PIECE
This includes the
time spent in loading
and unloading the
piece and the tool
approach time.
It can be reduced by
using jigs & fixtures,
centralized machining
concept etc.
88
89. TOOL CHANGING COST PER PIECE
This includes operators
time to change the tool
and to grind it.
89
90. This includes
depreciation of tool and
the cost of grinding.
TOTAL COST CURVE IS
THE SUM OF ALL
INDIVIDAUL CURVES.
90
TOOL REGRINDING COST PER PIECE
91. TOOL INSERT SPECIFICATION
Tool insert
Uncoated tungsten carbide tool-CNMG 12 04 08 H13 A
Make: Sandvik Coromant.
C Insert shape (C=80˚)
N Insert clearance angle (N=0˚)
M Tolerance ± on thickness (s)
G Insert type
12 Insert size (cutting edge l2 mm)
04 Insert thickness, s (04mm)
08 Insert radius, rɛ mm
94. CUTTING FLUIDS
To improve machinability , any substance applied to
the cutting zone during machining is called cutting
fluids.
Cutting fluids can act as coolant and as lubricant
A cutting fluid used to cool the tool and work piece is
called coolant
Water based coolants.
A cutting fluid used for the purpose of diminishing
friction between contacting surface in the cutting
zone is called lubricants.
Oil based fluids 94
95. FUNCTIONS OF CUTTING FLUIDS
1. To carry away the heat generated at work-tool
interface.
Tool hardness maintained
Less tool wear
Longer tool life
2. To reduce the friction at work tool interface.
Less power consumption.
Less heat generation
3. To flush away the chip from the tool.
4. To protect the finished surface from corrosion.
5. To break up the chip into small pieces.
6. To prevent formation of built-up edge.
7. To improve surface finish.
95
96. PROPERTIES OF CUTTING FLUIDS
It should posses good lubricating properties to minimize
friction at tool/work piece interface.
It should posses high heat absorption capacity.
It should not produce any skin irritation to the operator.
They should not emit obnoxious odours and vapours, harmful
to operator.
It should have less viscosity
It should be transparent.
It should be easily available at low price.
It should be chemically stable.
It should have high flash point.
96
97. TYPES OF CUTTING FLUIDS
A) Soluble oils (emulsions)
Water based cutting fluids
Mineral oil is dispersed in the form of fine droplets.
Oil & Water mixed in different proportions to get desired
properties.
Ratio varies from 1 : 5 to 1 : 50
Suitable for light cutting operations.
97
98. B) Straight oils
It is a mineral oil with suitable viscosity.
It has improved lubricating properties over soluble oils.
It maintains the lubricating film at low pressure.
98
99. C) Chemical additives
Additives such as sulphur and chlorine are used to
increase both the cooling & lubricating properties of oil.
It can maintain the lubrication film at extreme pressure.
Prevents the formation of built-up edge.
Suitable for machining low carbon steel.
D) Chemical compounds
Rust inhibitors such as sodium nitrate is mixed with high
percentage of water to obtain chemical compounds.
It prevents rust formation on machined surface.
Suitable for grinding operation 99
100. Solid Lubricants
Stick waxes, bar soaps and graphite powder are sometimes
used as solid lubricants.
100
101. SELECTION OF CUTTING FLUIDS
Cutting speed
Feed rate
Depth of cut
Tool and workpiece material
Viscosity of cutting fluid
Tool life to be expected
Economical aspects
Life of cutting fluids
101
102. CHIP BREAKERS
Long continuous chip are undesirable.
Chip breaker is a piece of metal clamped to the rake
surface of the tool which bends the chip and breaks it.
Chips can also be broken by changing the tool geometry,
thereby controlling the chip flow
Types
Step type
Groove type
Clamp type
102
103. Step type
A step is formed on the tool face behind the cutting edge.
Groove type
A groove is provided on the face behind the cutting edge.
Clamp type
A thin piece of material (chip breaker) is clamped or screwed
on the face of the tool.
103
104. CUTTING TOOL MATERIALS
Hot hardness
The material should remain harder than the work material at
elevated operating temperatures.
Wear resistance
The material must withstand excessive wear even though the
relative hardness of the tool-work material changes.
Toughness
The material must have sufficient strength to withstand shocks and
vibrations and to prevent breakage.
Cost and easiness in fabrication
The cost and easiness of fabrication should have within reasonable
limits.
104
106. Carbon steel
Plain carbon steel containing
Carbon - 0.8 – 1.3 %
Silicon 0.1 – 0.4 %
Manganese – 0.1 – 0.4 %
Suitable for low cutting speeds and cutting temperature
less than 200⁰c.
At heat treated & tempered condition this steel have
sufficient hardness, strength and toughness.
Heat treatment is done to provide keen cutting edge
This material is cheap , easy to forge and simple to
harden.
Suitable for
Taps & dies
Reamers
Hacksaw blades
106
107. HIGH SPEED STEEL
These tools can cut the material efficiently at high
speed.(2 to 3 times if carbon steel)
It has superior hot hardness and high wear resistance.
It maintains its hardness up to 900⁰C.
The various alloying elements added to improve its hot
hardness and wear resistance are
Tungsten
Chromium
Vanadium
Cobalt
molybdenum
Types of HSS
18-4-1 HSS
Molybdenum HSS
Cobalt HSS
107
108. 18-4-1 HSS
Tungsten - 18%
Chromium – 4 %
Vanadium – 1 %
Carbon – 0.75 %
Most commonly used tool steel.
Molybdenum HSS
Tungsten – 5 %
Chromium – 4 %
Vanadium – 2 %
Molybdenum – 6 %
It has high toughness and cutting ability.
Cobalt HSS
Tungsten – 20 %
Chromium – 4 %
Vanadium – 2 %
Cobalt – 15 % - (to increase hot hardness)
It is used for heavy duty and rough cutting tools in planers and milling
machines.
108
109. CEMENTED CARBIDES
Cemented carbides are made by mixing tungsten powder
and carbon at high temperature (1500⁰C) in the ratio 94 :
6 by weight.
Then it is combined with cobalt ,compacted and sintered
in a furnace about 1400 ⁰ C
It can be operated at higher cutting speed.
109
110. CERAMICS
Aluminium oxide and boron nitride powders are
mixed together and sintered at1700⁰C to form the
ingredient of ceramic tools.
It has high hardness and compressive strength.
It is made as tips and brazed/clamped on to the metal
shank for cutting
110
111. DIAMOND
Hardest cutting tool material.
It can be run at a speed 50 times greater than HSS
It can be made artificially by sintering at very high
pressure and temperature.
It has low coefficient of friction.
High compressive strength and wear resistance.
Low coefficient of thermal expansion.
111
113. SELECTION OF DIFFERENT WORK
PIECE MATERIALS
Hardness
Abrasive qualities
Toughness
Tendency to weld
Inherent hard spot and surface inclusion.
113