theory of tool wear

1. GROUP MEMBERS NAME
Sumit Mehta (A12405413023)
Utkarsh Chowdhary (A12405413022)
Mateshwari Prasad Mishra (A12405413037)
Ashwin (A12405413026)
Dhananjay Kumar (A12405413034)
Under the guidance of :- Ms. Khushbhu Yadav

2. 1. Factor of tool wear
2. Types of tool wear
3. Tool life
4. Machinability
5. Cutting fluids

3. FACTORS AFFECTING TOOL WEAR
 TOOL WEAR:-
Tool wear describes the gradual failure of cutting tools due to regular operation.
It is a term often associated with tipped tools , tool bits, or drill bits that are used
with machine tools.
 IMPACTS OF TOOL WEAR ARE:-
1)Extremely poor surface on the workpiece
2)High consumption of power
3)Overheating of the cutting tool
4)Metal to metal contact with work and chip
5)Virgin metal
6)Very high stress

4. OTHER FACTORS
 SOFTENING
1)Due to heat of the tool tip
2)The cutting becomes very hot
3)The tool deforms plastically at the tip
4) This deformation occurs due to cutting pressure and high temp.
Thus the tool looses its cutting ability and is said to have failed due to softening

5.  THERMAL CRACKING
1)Fluctution in temperature
2)Expansion and contraction in material
3)Rise in temperature and thermal stresses
Due to which cracks are developed & this is known as THERMAL CRACKS

6.  MECHANICAL CHIPPING
1)High cutting pressure
2)High mechanical impact
3)Too high vibration
4)This generally occurred in carbide tip or diamond tool due to high britlness of
the material

7. TYPES OF TOOL WEAR
There are 2 major types of tool wear-
1) Crater wear
2) Flank wear

8. CRATER WEAR
 The crater is on the rake face and is more or less circular
 It does not always extend to the tool tip it may end a distance
from the tool tip
 It increase the cutting forces, effects the tool geometry and
softens the tip.
 Thus making irregular in shape which decreases tool’s cutting
abilities

9. FLANK WEAR
 Flank wear is on the clearance surface of the tool.
 It modifies the tool geometry and changes cutting parameters
such as depth of cut.
 It makes the tool blunt and irregular .
 As tool wear progresses cutting forces increases and also
vibrations increses.

10. TOOL LIFE
 Tool life can be design as the time interval for which the tool
worths satisfactory between two successive grinding thus it can
basically consider as functional life of the tool .the tool is
subjected to wear continuously while it is operating so after some
time the tool looses its ability to cut decently and must be
degrounded.
There are three common ways to expressing tool life-
1) As the time period is minimum between two successive
grinding.
2) In terms of no of component machine.
3) In terms of volume of material removed.

11. a)volume of metal remove per minute= π. D.t.f.N mm^3/min
where,
D=dia of w/p in mm
t =depth of cut in mm
f =feed rate in mm/rev
N=no of revolution of work per min
b)Total volume of metal removed to tool failure=π.D.t.N.T mm^3
where,
T=time in min to tool failure and we know that
V= π.D.N/1000
Thus, π.D.N=V*1000
Where,
V=cutting speed.
So,
Total volume of metal remove to tool failure=1000.V.t.T
Therefore,
Tool life in term of tool failure=V.1000.t.f.T mm^3

12. FACTORS AFFECTING TOOL LIFE
1) Cutting speed
2) Tool material
3) Tool geometry
4) Rigidity of machine tool and work.
5) Feed and depth of cut
6) Work material
7) Nature of cutting
8) Use of cutting fluid

13. TOOL LIFE EQUATION
VT^n=C
Where,
T=tool life in min
V=cutting speed ,m/min
C and n are constant
Basically ‘n’ is known as tool life index-
n=0.1 to 0.15 for high speed steel tool.
n=0.2 to 0.5 for cemented carbide tool.
n=0.6 to 1.0 for ceramic tools.

14. Quantifying Machinability
 Tool life method
 Tool forces and power consumption method
 Surface finish method
 Mchinability rating
MACHINABILITY

15. Steels
Additives
Stainless steel
Aluminium

16. FUNCTIONS AND PROPERTIES OF
CUTTING FLUIDS
 Decrease the temperature of the tool and work piece.
 Reduce the friction.
 Protect the work against rusting.
 Improve the surface finish.
 Prevent the formation of build-up-edge.
 Wash away the chips from the cutting tool.
 Increase the tool life.

17. FUNTION OF CUTTING FLUIDS
 Cooling Action.
 Lubricating Action.
 On the back of the chip
 Along the rake crevice between the chip and rake face
of the tool.
 Along the clearance crevice between the finished work
surface and clearance face of the tool.
DIRECTION OF CUTTING FLUIDS

18. CUTTING FLUID APPIED METHOD
 Flooding
 Jet application
 Mist application

19. TYPES OF CUTTING FLUIDS
 Water base emulsions
 Straight minerals oils.
 Minerals oil with additives(Neat oils)