lijo's

1. Cutting Temperature
Dr Jose Mathew

2. Sources of heat generation in
cutting

3. Distribution of heat

4. Effects of High Temperature
On Tool:
Rapid Tool wear
Plastic deformation of edge
Thermal flaking and
deformation
BUE formation

5. Effects of High Temperature
On Workpiece:
*Thermal distortion and dimesional
inaccuracy
*Surface damage by oxidation,
corrosion, burning, etc.
*Thermal micro cracks and residual
stresses
> Hot machining

6. Purpose of measuring temp.
Assessment of machinability
Design and selection of cutting tools
Helps to proper selection of tools
Proper selection of cutting fluids
Analysis of temp distribution

7. Important parameters for temperature
θs : average shear zone temperature
θi : average (and maximum) temperature
at the chip-tool interface
θf : temperature at the work-tool interface (tool f
θavg : average cutting temperature
Measurement of Temperature
* Analytical
* Experimental

8. Analytical method
W=Wp+Ws ( W –total heat generated)
Ws =FVc=FrV
Wp=FcV-FrV
Ɵp =(1-ß)Wp / (ƿcVt1w)
-ß fraction of primary heat which goes to
the workpiece
- ƿ density of the material
- c sp. Heat of the material
- t1, w Uncut thickness, width of cut

9. is a function of shear angle Φ
and non dimesional quantity Ə
Ə= ƿcVt1/k
k-thermal conductivity of the material
ß =0.15 ln (27.5/ Ə tan Φ)
√
ƟS + 1.13 [ (Ət2/l)(Ws/ƿcvwt1)]
l - length of contact bet.tool and chip

10. Ɵs av = Ws/ƿcvwt1
l/t2 = [1+tan (Φ -α )]
Ɵs=1.13 √(1/ƿcvt1k[1+tan (Φ -α )] (Ws/w)
Ɵ= Ɵ0+ Ɵp +ƟS

11. Experimental methods

12. Tool work thermocouple method

13. Moving thermocouple

14. Embedded thermocouple

15. Compound rake used to measure the
cutting temperature along the rake face

16. Measuring temperature at shear plane
and tool flank by photocell technique

17. Temperature distribution at the
tool tip detected by infra ray
technique

18. Role of variation of the various
machining parameters on cutting
temperature