Cutting tools must possess certain key characteristics like hardness, toughness, wear resistance, and chemical stability. The selection of a cutting tool material depends on factors like the work material, cutting conditions, required surface finish, and cost. Common tool materials include high-speed steel, cast cobalt alloys, cemented carbides, ceramics, cubic boron nitride, and diamond. New developments in coated tools and ceramics have improved tool performance and allowed for higher cutting speeds.

1. Cutting Tool MateriCutting Tool Materi
Cutting tool must possess thCutting tool must possess th
Hardness
HSS Cast Carbid
Alloys WC
Hardness 83 86 82 84 1800Hardness 83-86 82-84 1800-
(N/mm²) HRA HRA 2400
Toughness
Wear ResistanceWear Resistance
Chemical Stability or Inert
ialsials
he following characteristics:he following characteristics:
es Ceramics CBN Diamond
TiC
1800 2000 4000 70001800- 2000- 4000- 7000-
3200 3000 5000 8000
ness

2. Hardness / Wear RResistance

3. ToughnessToughness

4. Relative time required t
various tool materialsvarious tool materials,
the tool materials were
to machine with
indicating the yearindicating the year
introduced

5. Selection of Cutting
FIGURE: The selection of the cutting-tool material
conditions for a given application
g Tool Materials
and geometry followed by the selection of cutting
n depends upon many variables

6. Cutting Tool Mag terial Hardness

7. Properties for GroupProperties for Groupps of Tool Materialsps of Tool Materials

8. General Characteristics o
Carbon &
Alloy
High
Speed
Cast
Cobalt
Unc
Car
Steels Steels Alloys
Car
Hot Hardness
Toughnessg
Impact
Strength
Wear
Resistance
Cutting Speed
ThermalThermal
Shock
Resistance
Cost of Tool
Material
Depth of cut
Light to
Medium
Light to
Heavy
Light to
Heavy
Lig
He
i i hFinish
Obtainable
Rough Rough Rough Go
of Cutting-Tool Materials
coated
rbides
Coated
Carbides
Ceramics
Cubic
Boron Diamond
rbides Carbides
Nitride
Increasing
Increasingg
Increasing
IncreasingIncreasing
Increasing
Increasing
IncreasingIncreasing
ht to
eavy
Light to
Heavy
Light to
Heavy
Light to
Heavy
Very Light
ood Good
Very
Good
Very
Good
Excellent

9. Alloy steels:Alloy steels:
Chromium: Improves strengt
and hot hardness. In significa
corrosion resistance.
Manganese: improves the str
Tungsten: increases toughne
Mol bden m increases to gMolybdenum: increases toug
Nickel: improves strength andNickel: improves strength and
Vanadium: inhibits grain grow
temperatures thereby enhanc
of steelof steel.
th, hardness, wear resistance,
nt proportions, Cr improves
rength and hardness of steel.
ess and hot hardness.
ghness and hot hardnessghness and hot hardness.
d toughness.d toughness.
wth during elevated
cing strength and toughness

10. Carbon SteelsCarbon Steels
Hi h C b t l (0 6 t 1 5% CHigh Carbon steel (0.6 to 1.5% Car
Small percentages of silicon, mang
used to help refine grain size and inused to help refine grain size and in
Easily shaped and sharpened
Greater resistance to abrasive wea
Do not have sufficient hot hardness
Widely used for files, saw blades, c
Speeds – 5 m/minSpeeds – 5 m/min
b )rbon)
ganese, chromium and vanadium are
ncrease tool hardnessncrease tool hardness
ar
s (200°C) for cutting at high speeds
chisels, taps, broaches and reamers

11. High Speed Steel
High speed tool steel differs from plain high c
steel in the addition of alloying elements to ha
strengthen the steel and make it more resistastrengthen the steel and make it more resista
(600 0C)
Commonly used alloying elements: many y g
chromium, tungsten, vanadium, molybde
and niobium
The M series (10% Mo, with Cr, V,
alloying elements) represents tool
molybdenum type and the T series
V and Cobalt as alloying elements)y g )
the tungsten type.
Weq = 2 (%Mo) + %Weq ( )
Some of the High SpeedSome of the High Speed
powdered metal (PM) fo
carbon
arden and
ant to heatant to heat
nganese,g ,
enum, cobalt
W and Cobalt as
steels of the
s (18% W, 4% Cr, 1%
) represents those of) p
d Steels are now available in ad Steels are now available in a
orm.

12. Cast Cobalt AlloysCast Cobalt Alloys
A typical composition for this cla
21% W, and 2% C which gives a
Cast alloys provide high abrasio
for cutting scaly materials
They are not as tough as HSS a
cutting operations.
When applying cast alloy tools, t
mind and sufficient support shou
Speeds – 45 to 60 m/min.
ss of tool material was 45% Co,
a hot hardness of 750 °C)
n resistance and are thus useful
and are sensitive for interrupted
their brittleness should be kept in
uld be provided at all times.

13. CarbidesCarbides
Also known as cement
Because of their high hardness (
thermal conductivity, abrasive re
carbides are the most importantp
and die materials for a w
Most carbide tools in use todayMost carbide tools in use today
carbides of W-Ti or W-Ti-Ta, de
be ma
Speeds –
ted or sintered carbides
(1000 °C), High elastic modulus,
esistance and chemical stability,
t, versatile and cost effective tool,
wide range of applications
y are either straight WC or multiy are either straight WC or multi
epending on the work material to
chined.
125 m/min.

14. Cemented Carbide
FIGURE: P/M process for making ce
e Inserts
emented carbide insert tools.

15. Production of WCProduction of WC
Blended WC powder produced byBlended WC powder, produced by
mixing WC (94%) with Cobalt (6%)
in a ball milling press
Carbide blending equipment,
Ball mill

16. Production of WCProduction of WC
Blended WC powder is then dried andp
compacted using a pill press
The compacted powder is then sintered inp p
a sintering furnace at 1350 to 1600 °C

17. CarbideCarbide
Typical carbide inserts with
features; round ins
The holes in the inserts are stThe holes in the inserts are st
InsertsInserts
various shapes and chip breaker
serts are also available.
tandardi ed for interchangeabilitytandardized for interchangeability.

18. Methods of attachingMethods of attaching
(a) Clamping, and
(c) threadless lockpins (d) In
inserts to toll holdersinserts to toll holders
(b) Wing lockpins
sert brazed on a tool shank

19. Boring Head
FIGURE: Boring head with carbide insert cuttin
cause the chips to curl tightly and br
ng tools. These inserts have a chip groove that can
reak into small, easily disposed lengths.

20. Insert StrengthInsert Strength
FIGURE: Relative edge strength and tendency for
chipping and breaking of inserts with various shapeschipping and breaking of inserts with various shapes.
Strength refers to that of the cutting edge shown by the
included angles. Source: Courtesy of Kennametal, Inc.
F
s
FIGURE: Edge preparations for inserts to improve edge
strength. Source: Courtesy of Kennametal, Inc.

21. Coated Carbide To
Necessity: New alloys and en
strength and toughness Thesestrength and toughness. These
chemically reac
Need for improving the performaNeed for improving the performa
materials has led to import
Coated tools don’t perform
The thickness of these coa
Speeds –
ools
ngineered materials, which have high
e materials are generally abrasive ande materials are generally abrasive and
ctive with tool materials.
ance in machining common engineeringance in machining common engineering
tant developments in coated tools.
m efficiently at low cutting speeds.
atings is on the order of 2 to 10 µm.
200 to 250 m/min.

22. Coating MaterialsCoating Materials
CTitanium Nitride:
(Gold Color)
Titanium Carb
(Gray Color
Low friction
ffi i t
These
ticoefficients,
high
hardness,
i t t
coatings
WC inse
have hig
fl kresistance to
high
temperature
d d
flank we
resistan
in
hi iand good
adhesion to
the substrate.
machinin
abrasiv
material
bide:
r)
Ceramics:
(Black Color)
e High chemical
inertness lowon
erts
gh
inertness, low
thermal
conductivity, high
thermal stabilityear
ce
thermal stability,
resistance to flank
and crater wear.
However ceramicng
ve
ls.
However ceramic
coatings bond
weakly to the
substratesubstrate.

23. Cutting inserts indicating the diverse range of shapes

24. Coating Materialsg
Diamond Coatings:
Effective in machining abrasive
materials
Tool life will be improved by ten
f ld h d t thfolds when compared to other
coated tools.
Poor adherence characteristics
and difference in thermal
expansion between diamond
and substrate materialsand substrate materials.
Titanium Carbo NitrideTitanium Carbo-Nitride
coatings:
Normally appears as the
intermediate layer of two or
three phase coatings.
Acts as a neutral layerActs as a neutral layer,
helping the other coating
layers to bond into a
sandwich-like structure.

25. Triple Coated Carbp
FIGURE: Triple-coated carbide tools provide
machining of steel, abrasive wear in c
bide Tools
resistance to wear and plastic deformation in
cast iron, and built-up edge formation.

26. Triple Coated Carb
FIGURE: Triple-coated carbide tools provid
hi i f t l b i imachining of steel, abrasive wear in
bide Tools
de resistance to wear and plastic deformation in
t i d b ilt d f tin cast iron, and built-up edge formation.

27. Multiphase CoatingMultiphase Coating
The first layer
The inter
lThe first layer
should bond
well with the
substrate
layer s
bond wel
compatib
b th thsubstrate both the
High speed,
continuous
Heavy
contincontinuous
cutting:
TiC/Al2O3
contin
cutti
TiC/Al2O
gsgs
The outer
layer should
rmediate
h ld layer should
resist wear
and have low
thermal
should
l and be
ble with
l thermal
conductivity
layers.
duty,
uous
Light,
interrupted
tti
uous
ng:
O3/TiN
cutting:
TiC/TiC +
TiN/TiN

28. Multiphasep
Multiphase coatings on a tungsten carbide sub
are separated by very thin layers of titanium
coatings have been made. Coating thickn
e Coatingsg
bstrate. Three alternating layers of aluminum oxide
nitride. Inserts with as many as thirteen layers of
esses are typically in the range of 2 to 10 m..

29. CVD Process:CVD Process:
FIGURE: Chemical vapor deposition is used to apply layers (TiC, TiN, etc.) to carbide cutting tools.

30. PVD ProcessPVD Process
FIGURE: Schematic of PPVD evaporation process

31. Ceramics (Cement(
Ceramics are non-metallic materia
The main constituent is Al2O3 , up
Extremely high resistance to
Extremely high hot hardness (1400
The application of ceramic cutting tooThe application of ceramic cutting too
brittleness. The transverse rupt
The strength of ceramics under compressg p
tools and they can be used
To use ceramic tools successfully, insert sh
capability set up and general machcapability, set-up, and general mach
ted Oxides))
als produced by sintering process.
pto 10% oxides of Mg, Ti and Cr
abrasive wear and cratering.
0 °C) and low thermal conductivity
ols is limited because of their extremeols is limited because of their extreme
ture strength (TRS) is very low.
ion is much higher than HSS and carbideg
at speeds upto 250 m/min.
ape, work material condition, machine tool
hining conditions must all be correcthining conditions must all be correct.

32. Various sizes and shapes of hhot and cold pressed ceramics

33. Sialon (Si Al O N)Sialon (Si-Al-O-N)
P d d b illi tProduced by milling tog
nitride, alumi
Dried and pressed to s
temperature of
Sialons are considerabl
Can be used success
involving inte
Cutting speeds –
th Si N Al i igether Si3N4, Aluminium
ina and yttria.
shape and sintered at a
f about 1800 °C
ly tougher than alumina.
sfully during machining
errupted cuts.
200 to 300 m/min.

34. CermetsCermets
C t b i ll bCermets are basically a comb
carb
The manufacturing process
process used for ho
The materials, approximately
The strength of cermets is gr
ceramics. Therefore, cermets,
cu
However, when compared to s
30% TiC i t d30% TiC in cermets decre
resistance to
bi ti f i d tit ibination of ceramic and titanium
bide.
s for cermets is similar to the
ot pressed ceramics.
y 70% ceramic and 30 % TiC.
reater than that of hot pressed
s perform better on interruptedp p
uts.
solid ceramics, the presence of
th h t h d deases the hot hardness and
abrasive wear.

35. DiamondDiamond
Diamond is the hard
Diamond tools have high
conductivity very low friconductivity, very low fri
most materials, the abi
edge for a long time and
Diamond cutting tools sho
finishing cuts of precision
b li ht d dbe very light and speeds
5000 S
dest material known
h hardness, good thermal
ction non adherence toction, non-adherence to
ility to maintain a sharp
a good wear resistance.
ould only be used for light
n surfaces. Feeds should
ll i fs are usually in excess of
SFPM

36. Disadvantages of DDisadvantages of D
Rigidity in the machine tool
Because diamonds are p
affinity for the carbon in the f
they can only be usedthey can only be used
Diamond has a tendency toDiamond has a tendency to
(7000 C) to graphite
Diamond is very brittle and
too
DiamondDiamond
and the setup is very critical
pure carbon, they have an
ferrous materials. Therefore,
on non-ferrous metalson non-ferrous metals.
revert at high temperaturesrevert at high temperatures
and/or oxidize in air.
costly to shape into cutting
ols.

37. Polycrystalline
Di d T lDiamond Tools
FIGURE: Polycrystalline diamond tools are
carbides with diamond inserts.
They are restricted to simple geometries.

38. Polycrystalline diamond mateerial bonded to a carbide base.

39. Polycrystalline Cubic BPolycrystalline Cubic B
CBN is similar to diamond in itCBN is similar to diamond in it
is also bonded (a layer of 0.5 t
bas
While the carbide provides sho
provides very high wear re
stren
With the exception of titanium,
CBN will work effectively as a
work mawork ma
CBN should mainly be con
material because of its extremmaterial because of its extrem
Machine tool and set-up rigiditMachine tool and set up rigidit
criti
Boron Nitride (PCBN)Boron Nitride (PCBN)
ts polycrystalline structure andts polycrystalline structure and
to 1.0 mm PCBN) to a carbide
se.
ock resistance, the CBN layer
esistance and cutting edge
ngth.
, or titanium alloyed materials,
cutting tool on most common
aterialsaterials.
nsidered as a finishing tool
me hardness and brittlenessme hardness and brittleness.
ty for CBN as with diamond isty for CBN as with diamond is
cal

40. Cubic BoroCubic Boro
Construction of a polycrystalline cubic boron
nitride or a diamond layer on a tungsten-carbide
i tinsert.
on Nitrideon Nitride
Inserts with polycrystalline cubic boron nitride
tips (top row) and solid polycrystalline cBN
i t (b tt )inserts (bottom row).

41. Improvements in Cp
FIGURE: Improvements in cutting tool materials
(and productivity
Cutting speedsg p
have led to significant increases in cutting speeds
y) over the years.

42. Approximate Cost of SApproximate Cost of S
TABLE
Tool
High-speed steel tool bitsHigh speed steel tool bits
Carbide-tipped (brazed) tools for turning
Carbide inserts, square 3/16"thick
Plain
CoatedCoated
Ceramic inserts, square
Cubic boron nitride inserts, square
Diamond coated insertsDiamond-coated inserts
Diamond-tipped inserts (polycrystalline)
Selected Cutting ToolsSelected Cutting Tools
Size (in.) Cost ($)
1/4 sq.x 2 1/2 long 1–21/4 sq.x 2 1/2 long 1 2
1/2 sq. x 4 3–7
1/4 sq. 2
3/4 sq 43/4 sq. 4
1/2 inscribed circle 5–9
6 106–10
1/2 inscribed circle 8–12
1/2 inscribed circle 60–90
1/2 inscribed circle 50 601/2 inscribed circle 50–60
1/2 inscribed circle 90–100

43. THATHAANK YOUANK YOU