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ME - 535 METAL CUTTING
MIDDLE EAST TECHNICAL UNIVERSITY MECHANICAL
ENGINEERING DEPARTMENT
TEMPERATURES IN METAL CUTTING
By Prof.Dr.Ömer ANLAGAN
Ankara,2001
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1. INTRODUCTION
TEMPERATURES IN METAL CUTTING 1.
Introduction 2. Heat Generation in Metal
Cutting 3. Heat Transfer in a Moving
Material 4. Temperature Distribution in
Metal Cutting 4.1 Temperatures in the
Primary Shear Zone 4.2 Temperatures in the
Secondary Shear Zone 4.3
Effect of Cutting Speed on
Temperature 5. Measurement of Cutting
Temperatures
During the metal cutting, high temperatures are
generated in
Primary shear zone (A-B) plastic
deformationSecondary shear zone (C-B)
frictionBetween tool and workpiece (D-B)
plowing force (negligible)
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TEMPERATURES IN METAL CUTTING 1.
Introduction 2. Heat Generation in Metal
Cutting 3. Heat Transfer in a Moving
Material 4. Temperature Distribution in
Metal Cutting 4.1 Temperatures in the
Primary Shear Zone 4.2 Temperatures in the
Secondary Shear Zone 4.3
Effect of Cutting Speed on
Temperature 5. Measurement of Cutting
Temperatures
High temperature
- shortens tool life - causes thermal
distortion- causes dimensional changes in the
workpiece, making control of dimensional
accuracy difficult
To use coolant is an efficient method to reduce
the cutting zone temperature
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2. HEAT GENERATION IN METAL CUTTING
TEMPERATURES IN METAL CUTTING 1.
Introduction 2. Heat Generation in Metal
Cutting 3. Heat Transfer in a Moving
Material 4. Temperature Distribution in
Metal Cutting 4.1 Temperatures in the
Primary Shear Zone 4.2 Temperatures in the
Secondary Shear Zone 4.3
Effect of Cutting Speed on
Temperature 5. Measurement of Cutting
Temperatures
Energy consumption (or heat generated) during
machining Pm
Fc cutting forceV cutting speed
Pm Fc V
Ps heat generated in primary shear zonePf
heat generated in secondary shear zone
Pm Ps Pf
Pf Ff V0
Ff friction forceV0 velocity of chip flow
V0 V rc
rc ac / a0
where
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TEMPERATURES IN METAL CUTTING 1.
Introduction 2. Heat Generation in Metal
Cutting 3. Heat Transfer in a Moving
Material 4. Temperature Distribution in
Metal Cutting 4.1 Temperatures in the
Primary Shear Zone 4.2 Temperatures in the
Secondary Shear Zone 4.3
Effect of Cutting Speed on
Temperature 5. Measurement of Cutting
Temperatures
3. HEAT TRANSFER IN A MOVING MATERIAL
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TEMPERATURES IN METAL CUTTING 1.
Introduction 2. Heat Generation in Metal
Cutting 3. Heat Transfer in a Moving
Material 4. Temperature Distribution in
Metal Cutting 4.1 Temperatures in the
Primary Shear Zone 4.2 Temperatures in the
Secondary Shear Zone 4.3
Effect of Cutting Speed on
Temperature 5. Measurement of Cutting
Temperatures
Heat transfer across AB
Heat transfer across CD
Heat transfer across AD
Heat transfer across BC
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TEMPERATURES IN METAL CUTTING 1.
Introduction 2. Heat Generation in Metal
Cutting 3. Heat Transfer in a Moving
Material 4. Temperature Distribution in
Metal Cutting 4.1 Temperatures in the
Primary Shear Zone 4.2 Temperatures in the
Secondary Shear Zone 4.3
Effect of Cutting Speed on
Temperature 5. Measurement of Cutting
Temperatures
Net heat flow into the element 0
(i.e. the amount of heat entering the control
volume is equal to that of leaving it)
QAB QAD QCD QBC
Therefore
(3.3)
R, thermal number
v cutting speedac undeformed chip thickness
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4. TEMPERATURE DISTRIBUTION IN METAL CUTTING
TEMPERATURES IN METAL CUTTING 1.
Introduction 2. Heat Generation in Metal
Cutting 3. Heat Transfer in a Moving
Material 4. Temperature Distribution in
Metal Cutting 4.1 Temperatures in the
Primary Shear Zone 4.2 Temperatures in the
Secondary Shear Zone 4.3
Effect of Cutting Speed on
Temperature 5. Measurement of Cutting
Temperatures
Temperature distribution in workpiece and tool
during orthogonal cutting (V25m/s , HSS tool)
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TEMPERATURES IN METAL CUTTING 1.
Introduction 2. Heat Generation in Metal
Cutting 3. Heat Transfer in a Moving
Material 4. Temperature Distribution in
Metal Cutting 4.1 Temperatures in the
Primary Shear Zone 4.2 Temperatures in the
Secondary Shear Zone 4.3
Effect of Cutting Speed on
Temperature 5. Measurement of Cutting
Temperatures
Heat generated during cutting is distributed
among chip, workpiece and tool
Pm Qc Qw Qt
(3.4)
Pm total rate of heat generationQc rate of
heat transportation by the chipQw rate of heat
conduction into the workpieceQt rate of heat
conduction into the tool
Qt has usually very small proportion in Pm .
Except at very low cutting speeds, it may be
neglected.
The maximum temperature in the tool/chip
interface area is almost in the middle of the
tool/chip contact length.
Particular temperature distribution depends on
specific heat and thermal conductivity of tool
work pair materials, cutting conditions such as
cutting speed, feed, depth of cut and type of
cutting fluid.
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4.1 TEMPERATURES IN THE PRIMARY SHEAR ZONE
TEMPERATURES IN METAL CUTTING 1.
Introduction 2. Heat Generation in Metal
Cutting 3. Heat Transfer in a Moving
Material 4. Temperature Distribution in
Metal Cutting 4.1 Temperatures in the
Primary Shear Zone 4.2 Temperatures in the
Secondary Shear Zone 4.3
Effect of Cutting Speed on
Temperature 5. Measurement of Cutting
Temperatures
volume flow
energy generated
energy carried away
Or,
(3.5)
where
Ps heat generation in primary shear zoneG
portion of Ps which is conducted to the
workpiece, so, this portion will not cause
temperature increase in chip?s average
temperature rise in primary shear zoneC
specific heat? densityv cutting
speedac undeformed chip thicknessaw depth
of cut
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TEMPERATURES IN METAL CUTTING 1.
Introduction 2. Heat Generation in Metal
Cutting 3. Heat Transfer in a Moving
Material 4. Temperature Distribution in
Metal Cutting 4.1 Temperatures in the
Primary Shear Zone 4.2 Temperatures in the
Secondary Shear Zone 4.3
Effect of Cutting Speed on
Temperature 5. Measurement of Cutting
Temperatures
The idealized model of the cutting process
defined by Weiner and Rapier
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TEMPERATURES IN METAL CUTTING 1.
Introduction 2. Heat Generation in Metal
Cutting 3. Heat Transfer in a Moving
Material 4. Temperature Distribution in
Metal Cutting 4.1 Temperatures in the
Primary Shear Zone 4.2 Temperatures in the
Secondary Shear Zone 4.3
Effect of Cutting Speed on
Temperature 5. Measurement of Cutting
Temperatures
Weiner assumed that no heat was conducted in the
material in the direction of its motion and
simplified the heat transfer equation to
(3.6)
The following figure shows the theoretical
solution of Weiner and experimental work of
Nakayama for expressing the relationship between
G and RtanF.
It can be seen that the theory has slightly
underestimated G at high values of RtanF (i.e.,
at high speeds and high feeds) due to the plane
heat source assumption.
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TEMPERATURES IN METAL CUTTING 1.
Introduction 2. Heat Generation in Metal
Cutting 3. Heat Transfer in a Moving
Material 4. Temperature Distribution in
Metal Cutting 4.1 Temperatures in the
Primary Shear Zone 4.2 Temperatures in the
Secondary Shear Zone 4.3
Effect of Cutting Speed on
Temperature 5. Measurement of Cutting
Temperatures
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TEMPERATURES IN METAL CUTTING 1.
Introduction 2. Heat Generation in Metal
Cutting 3. Heat Transfer in a Moving
Material 4. Temperature Distribution in
Metal Cutting 4.1 Temperatures in the
Primary Shear Zone 4.2 Temperatures in the
Secondary Shear Zone 4.3
Effect of Cutting Speed on
Temperature 5. Measurement of Cutting
Temperatures
4.2 TEMPERATURES IN THE SECONDARY SHEAR ZONE
(Friction Zone)
Rapier assumed that the heat zone resulting from
friction between chip and tool is a plane heat
source when solving the Equation 3.6.
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TEMPERATURES IN METAL CUTTING 1.
Introduction 2. Heat Generation in Metal
Cutting 3. Heat Transfer in a Moving
Material 4. Temperature Distribution in
Metal Cutting 4.1 Temperatures in the
Primary Shear Zone 4.2 Temperatures in the
Secondary Shear Zone 4.3
Effect of Cutting Speed on
Temperature 5. Measurement of Cutting
Temperatures
The following expression was obtained.
(3.7)
where
?f average temperature rise in chip due to
frictional heating ?m maximum temperature rise
in chip due to frictional heating
This result does not agree with the experimental
observations (given in the next page). Equation
3.7 overestimates ?m. The reason is that the
heat generation does not take place in a plane .
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TEMPERATURES IN METAL CUTTING 1.
Introduction 2. Heat Generation in Metal
Cutting 3. Heat Transfer in a Moving
Material 4. Temperature Distribution in
Metal Cutting 4.1 Temperatures in the
Primary Shear Zone 4.2 Temperatures in the
Secondary Shear Zone 4.3
Effect of Cutting Speed on
Temperature 5. Measurement of Cutting
Temperatures
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TEMPERATURES IN METAL CUTTING 1.
Introduction 2. Heat Generation in Metal
Cutting 3. Heat Transfer in a Moving
Material 4. Temperature Distribution in
Metal Cutting 4.1 Temperatures in the
Primary Shear Zone 4.2 Temperatures in the
Secondary Shear Zone 4.3
Effect of Cutting Speed on
Temperature 5. Measurement of Cutting
Temperatures
heat generatedin friction zone
heat carried awayfrom friction zone
(3.8)
Finally, the maximum temperature in chip can be
obtained by
?max ?m ?s ?0
(3.9)
where
?m maximum temperature rise in chip due to
frictional heating ?s average
temperature rise in primary shear zone ?0
initial temperature of the workpiece
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TEMPERATURES IN METAL CUTTING 1.
Introduction 2. Heat Generation in Metal
Cutting 3. Heat Transfer in a Moving
Material 4. Temperature Distribution in
Metal Cutting 4.1 Temperatures in the
Primary Shear Zone 4.2 Temperatures in the
Secondary Shear Zone 4.3
Effect of Cutting Speed on
Temperature 5. Measurement of Cutting
Temperatures
4.3 EFFECT OF CUTTING SPEED ON TEMPERATURE
If cutting speed increases, heat generation
increases. Increase in heat generation causes
temperature increase only where the heat transfer
does not increase by higher speed, i.e., at tool
face.
?s?m
?s
Mean Surface Temperature ?s?m
T (?C)
Mean Shear Zone Temperature ?s
V (m/s)
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TEMPERATURES IN METAL CUTTING 1.
Introduction 2. Heat Generation in Metal
Cutting 3. Heat Transfer in a Moving
Material 4. Temperature Distribution in
Metal Cutting 4.1 Temperatures in the
Primary Shear Zone 4.2 Temperatures in the
Secondary Shear Zone 4.3
Effect of Cutting Speed on
Temperature 5. Measurement of Cutting
Temperatures
5. MEASUREMENT OF CUTTING TEMPERATURE

• 1. Work Tool Thermocouple
• Most widely used
• - Limited since it can not give the temperature
  distribution on
• chip-tool interface
• Calibration is needed for each tool/workpiece
  combination
• - Calibration of stationary tool may not give the
  same values
• during cutting

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TEMPERATURES IN METAL CUTTING 1.
Introduction 2. Heat Generation in Metal
Cutting 3. Heat Transfer in a Moving
Material 4. Temperature Distribution in
Metal Cutting 4.1 Temperatures in the
Primary Shear Zone 4.2 Temperatures in the
Secondary Shear Zone 4.3
Effect of Cutting Speed on
Temperature 5. Measurement of Cutting
Temperatures
5. MEASUREMENT OF CUTTING TEMPERATURE
Work Tool Thermocouple measurement technique
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TEMPERATURES IN METAL CUTTING 1.
Introduction 2. Heat Generation in Metal
Cutting 3. Heat Transfer in a Moving
Material 4. Temperature Distribution in
Metal Cutting 4.1 Temperatures in the
Primary Shear Zone 4.2 Temperatures in the
Secondary Shear Zone 4.3
Effect of Cutting Speed on
Temperature 5. Measurement of Cutting
Temperatures
5. MEASUREMENT OF CUTTING TEMPERATURE
2. Direct Thermocouple Measurements i. Nakayama
technique (see figure below) ii. Thermocouple
inserted on tool shank to measure insert
temperature
Nakayama cutting temperature measurement technique
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TEMPERATURES IN METAL CUTTING 1.
Introduction 2. Heat Generation in Metal
Cutting 3. Heat Transfer in a Moving
Material 4. Temperature Distribution in
Metal Cutting 4.1 Temperatures in the
Primary Shear Zone 4.2 Temperatures in the
Secondary Shear Zone 4.3
Effect of Cutting Speed on
Temperature 5. Measurement of Cutting
Temperatures
5. MEASUREMENT OF CUTTING TEMPERATURE
3. Infrared Radiation Suitable for determining
of temperature distribution in the cutting
zone i. Radiation pyrometer method ii.
Infrared photograph of cutting operation iii.
Thermal imaging camera, an improved method for
infrared radiation
4. Others
i. Calorimetric techniques ii.
Temperature-sensitive chemicals
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