Detail study of cutting tool materials, some special materials, carbide tip tools, carbide inserts, types, carbide insert holders, ISO designation of carbide inserts, single point cutting tool nomenclature and angles, tool geometry, Tool life, tool wear and types, machinability

1. Manufacturing Eng. II
Cutting Tools and Tool Holders
Chapter 5
Gaurav Mistry
Assistant Professor
Diwaliba Polytechnic, UTU.

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❑ Cutting Tools & Tool Holders Manufacturing Eng. - II
What is Cutting Tool?
• In the context of machining, a cutting
tool or cutter is any tool that is used to
remove some material from the work
piece by means of shear deformation.
• Cutting may be accomplished by
single-point or multipoint tools.
• Single-point tools are used in turning,
shaping, planning and similar
operations, and remove material by
means of one cutting edge.
• Milling and drilling tools are often
multipoint tools. It is a body having
teeth or cutting edges on it. Grinding
tools are also multipoint tools

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What is Tool Holder?
• A tool holder is a machining component that holds the tool in place. Its purpose is
to hold the tool in place as precisely and firmly as possible.
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Cutting tool Materials, Alloying elements and Properties:
• The Principal Cutting tool material are:
1. Carbon Steels
2. Medium alloy steels.
3. High speed steels.
4. Stellite.
5. Cemented carbides.
6. Ceramics.
7. Diamonds.
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Characteristics of Cutting Tool Materials:
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Characteristics of Cutting Tool Materials:
1. Carbon Steel:
• Tools of complex form should not be made with carbon steel.
• Only applicable for low cutting speeds (about 12 m/min) since its hardness is
substantially reduced at temperature above 190-200 degree C.
2. Alloy Steel:
• Compared to plain carbon steel it has 5% alloy content consisting of tungsten,
molybdenum, chromium and vanadium in addition.
• It has medium performance between plain carbon and high speed steels.
• They loose their required hardness at temperature from 250 to 350 degree C.
3. High Speed Steels:
• They have high red hardness, high wear resistance to retain cutting property up to
600 – 620 degree C.
• 18-4-1 HSS: 18 % tungsten, 4% chromium and 1% vanadium with carbon of 0.6 –
0.7 %
• Cobalt HSS/Super HSS: cobalt is added from 2 to 15 % to increase hot hardness
and wear resistance along with tungsten, chromium and vanadium.
• Molybdenum HSS: (6% tungsten/6% molybdenum) i.e. little % of tungsten is
compensated by addition of molybdenum. Excellent toughness and cutting ability.
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Characteristics of Cutting Tool Materials:
4. Stellite:
• It is non ferrous alloy with range of elements: 40 – 48 % cobalt, 30 – 35 %
chromium and 12 – 19 % tungsten. Carbon is added to 1.8 – 2.5 %.
• They cannot be forged to shape.
• They preserve hardness up to 1000 degree C.
• Can be operated at cutting speed 2 times higher than HSS.
• Not widely used for metal cutting since they are very brittle, however used
extensively in some non metal cutting applications like rubbers, plastics where
loads are gradually applied.
5. Cemented Carbides:
• The name is for they are composed principally of carbon mixed with other
elements.
• Tungsten carbide is mixed with cobalt. Also boron, titanium and tantalum are also
used to form carbides.
• Carbide tools are made by brazing or silver – soldering.
• Cemented carbides have high heat & wear resistance, high compressive strength.
• Types: Tungsten type cemented carbide and Titanium – tungsten type cemented
carbide.
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Characteristics of Cutting Tool Materials:
6. Ceramics:
• Aluminium oxide powder is compacted in a mould at about 28 MN/𝑚2 and
sintered (https://en.wikipedia.org/wiki/Sintering) at 2200 degree C.
• Hot pressing are more expensive then above cold pressing due to higher mould
costs.
• Low heat conductivity (so used without a coolant) and high compressive strength.
• Also Brittle with low bending strength.
• To give increased strength to ceramic tools, often ceramic with a metal bond
known as cermet's is used.
7. Diamond:
• Hardest know material.
• Cutting speed about 50 times greater than HSS and at temperature up to 1650
degree C.
• It is incompressible, good conductor of heat and has low coefficient of friction.
• Suitable for cutting very hard materials such as glass, plastics, ceramics and other
abrasive materials.
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Special Cutting Tool Materials:
1. Coated Carbides:
• By providing 4 – 8 mm thick coating of titanium carbide, titanium nitride by vapour
deposition technique, the wear resistance and toughness properties of simple
carbide are increased.
• Friction is also reduced and it reduces 15 – 20 % of cutting force.
• This type of tool enhances metal removal rate and also tool life.
2. UCON:
• This material is product of Union Carbide of USA.
• Its hardness is 2500 – 3000 Vickers (unit for hardness HV, Vickers Pyramid
Number) (Generally measured in pascal, used in Vickers hardness test)
• It has best thermal shock resistance, high hardness and toughness.
• Highly resistant to diffusion and adhesion wear.
• Its life is 4 times that of carbides.
• It has limited application to turning, facing and boring.
• It is not used for milling, parting and form tools and also for nickel, cobalt and
titanium based stainless steel and super alloy.
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Special Cutting Tool Materials:
3. Cubic boron nitride (CBN):
• It is second in hardness to diamond.
• It contain nitrogen and boron.
• It has high hardness and thermal conductivity.
• It does not react with oxygen.
• It does not chemically react with iron even at high temperature.
• It is used in grinding wheel for grinding HSS.
• It is used for grinding lead screw, splines, threads, ball and roller bearings, cast iron
slide ways, etc.
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Carbide Insert Tools:
Production process:
• Carbide inserts or tips are produced from tungsten carbide (WC) or cobalt
carbide (Co) powder by powder metallurgy using suitable binder.
• The required shape is given by moulding. The moulded insert is then machined to
necessary sharpness and cutting edge.
• Around 1850 HV hardness can be obtained with carbide WC 93% and Co 7%.
• When sintered at 1300 – 1600 degree C, becomes extremely strong with hardness
almost double the hardness of HSS tools.
Need:
• Manufacturing of carbon steel and HSS components require carbide tipped tool for
their machining operation.
• CNC machines require carbide tipped tools for high speed and feed manufacturing
process. (where HSS and other material tools cannot be used.)
• Large sized heavy duty casting and forgings are machined by carbide tipped tools
only.
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Carbide Insert Tools:
Advantages:
• Hardness is double than HSS and carbon steel tools.
• Used for high speed and high feed machining and hence increase the production
rate.
• Very high compressive strength.
• Do not wear out easily and hence not needed to be changed frequently.
• They can be made smaller size and can conveniently fitted on tool holder.
Types of Carbide Tips:
• There are two types of carbide tips:
I. Brazed tip: This type of tips are brazed on the face of cutting tool.
II. Indexable inserts: It is clamped in tool holder. It has more than one cutting edge.
It is also known as throw away tips. They are available in Triangular, diamond
and square shapes.
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Carbide Insert Tools: I.S.O designations
• Maximum 13 symbols are used to indicate the type of indexable carbide
inserts. http://www.carbidedepot.com/formulas-insert-d.htm
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Carbide Tool Holders:
• Different types of tool holders are used for different types of machining operations.
• There are three methods of fixing carbide inserts on tool holders:
a. Brazed to the tool.
b. Fitted by screw in a given hole.
c. Clamped with help of clamp or screw.
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General Cutting Tool Parameters:
o There are three important parameters:
1. Cutting Speed: The travel of a point on cutting edge
relative to the surface of the cut in unit time.
• In lathe, when a workpiece of D diameter in mm rotates at
a speed of N revolutions per minute, then the cutting speed
V is given by V =
𝜋𝐷𝑁
1000
m/min
2. Feed: Also called rate of feed is the amount of tool
advancement per revolution of job parallel to the surface being
machined. It is expressed as the distance moved by tool in one
minute, unit is mm/rev.
• Feed depends on depth of cut, rigidity of cutting tool and
type of cutting tool material.
3. Depth of Cut: The thickness of layer of metal removed in
one cut or pass measured in a direction perpendicular to the
machined surface.
• It is always perpendicular to the direction of feed motion.
• In external longitudinal turning, the depth of cut is half the
difference between the work diameter D1 and the diameter
of machined surface D2 obtained after one pass.
• T =
D1 - D2
2
mm.
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Tool Nomenclature and Tool Angle:
(Single Point Cutting Tool)
1. Shank: The shank is that portion of the tool
bit which is not ground to form cutting edges and is
rectangular in cross – section.
2. The Base: The base of a tool is the under slide of
the shank. It takes the tangential pressure of the cut.
3. Heel: The heel of a single point tool
is the lowest portion of the side cutting
edges.
4. Face: The face of the cutting tool is that surface against which the chip slides upward.
❑ Cutting Tools & Tool Holders
Minor
flank
Major
flank

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Tool Nomenclature and Tool Angle:
(Single Point Cutting Tool)
5. Flank: The flank of a cutting tool is that surface
which face the work piece. (Minor and Major Flank)
6. Tool Point: The part of tool which is shaped to produce
the cutting edge and face.
7. Cutting edge: The portion of face edge along which
the chip is separated from the work. It consist of side
cutting edge, nose and end cutting edge.
8. Nose: The nose of a tool is the conjunction of the
side and end cutting edges. A nose radius increases the
tool life and improves surface finish.
9. Neck: The neck is an extension of the shank of reduced sectional area.
❑ Cutting Tools & Tool Holders
Minor
flank
Major
flank

18. Minor
flank
Major
flank
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Manufacturing Eng. - II
Tool Nomenclature and Tool Angle:
(Single Point Cutting Tool)
10. Back rake angle: It is the angle of face to the
Plane Parallel to the Shank in longitudinal direction
of shank. It guides the direction of chip flow.
The back rake angle may be positive, zero or negative.
11. Side rake angle: The slope of the Top surface
to the side in a direction Perpendicular to the
longitudinal axis.
12. End relief angle: The angle between plane
perpendicular to the base and longitudinal
axis and the minor flank surface (flank edge).
13. Side relief angle: The angle made by Flank edge of the tool and a side plane perpendicular
to the base but parallel to longitudinal axis under side cutting edge.
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19. Minor
flank
Major
flank
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Tool Nomenclature and Tool Angle:
(Single Point Cutting Tool)
14. End cutting edge angle: It is the angle between
the end cutting edge of the tool and plane
perpendicular to the longitudinal axis
( or parallel to the cross section of the shank).
15. Side cutting edge angle: It is the angle between the
side cutting edge and side plane parallel to the
longitudinal axis of the tool.
16. Nose radius: The nose radius is provided to
increase the finish and strength of the cutting tip of the tool.
17. Lip Angle: The lip or cutting angle is the included angle between face and flank (minor and
major both).
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Tool Signature (Single Point Cutting Tool):
:
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Tool Life:
• It is desired that the tool life should be as long as possible so that machining may
become economical.
• It is usually expressed as the time for which the cutting edge lasts.
• Other criteria's to specify the tool life are:
1) Actual cutting time to failure.
2) Volume of metal remove to failure.
3) Number of components produce to failure.
Tool Wear:
1. Abrasive wear.
2. Diffusion wear.
3. Attrition wear (Built up edge).
4. Electro chemical wear.
5. Chemical wear.
6. Plastic deformation.
7. Thermal cracking.
8. Flank wear.
9. Carter wear.
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Machinability:
• It is defined as the ease with which machining operation can be performed on the
workpiece. It is evaluated under different circumstances considering the following
factors:
1) Tool Life.
2) Limiting rate of metal removal.
3) Cutting force or power consumption.
4) Surface finish.
5) Chip shape.
Resharpening or Grinding of cutting tool Methods:
1) Simple Grinding Machine.
2) Universal tool and cutter grinder
3) Special tool grinder.
a. Dry Grinding.
b.Wet Grinding.
c. Peripheral Grinding.
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Different tools Geometry other than single point tool:
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Different tools Geometry other than single point tool:
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REFERENCES:
1. www.google.com
2. ME – II, R. R. Mahitcha and C. M. Desai, Atul Prakashan
❑ Cutting Tools & Tool Holders Manufacturing Eng. - II