Transcript Comparison between Experimental & Numerical Results for Single Point Diamond Turning (SPDT) of silicon carbide (SiC) John Patten, Director Manufacturing Research Center Western Michigan University NAMRC.

Comparison between Experimental & Numerical
Results for Single Point Diamond Turning (SPDT)
of silicon carbide (SiC)
John Patten, Director
Manufacturing Research Center
Western Michigan University
NAMRC 35
May 22, 2007
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Agenda
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•
•
•
Introduction to Silicon Carbide (SiC)
Background of HPPT Research
Background of ceramic simulations
2-D orthogonal machining simulations
– Simulations of edge turning
– Simulation of plunge cutting
– Simulations of fly-cutting
• 3-D scratching simulations
– Silicon Carbide
• Summary of results
• Conclusions and future work
2
Silicon Carbide – Advanced Engineering Ceramic
•
•
•
Types of SiC
Properties and applications of SiC
Problems in manufacturing
3
Research background – HPPT of ceramics
• Define HPPT
• HPPT or amorphization of ceramics is responsible for the
ductile behavior of these brittle materials.
• HPPT has been identified in Si and Ge, and other materials.
• Ductile material removal has been achieved in SiC under
nanometer cutting conditions and phase transformation of
chips has been recorded.
• Some factors contributing to ductile material removal at room
temperature
– machining depth < tc
– negative rake angle tools with small clearance
– sharp edge radius
4
Developments in simulations of ceramic machining
• Introduce AdvantEdge
• Developments in AdvantEdge
– 2-D simulations of Silicon Carbide in the nanometer
regime
– 2-D simulations of Silicon Carbide using DP model
– Newly developed 3-D scratching simulation capability
• Other developments outside AdvantEdge
– FEA simulation of polycrystalline alpha-SiC
– MD simulations of nanoindentation in SiC
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2-D orthogonal machining simulations of SiC
• Three types of experiments were simulated
– Edge turning of SiC
– Plunge cutting of SiC
– Fly-cutting of SiC
Visualization of 3-D turning operation in 2-D
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Typical setup for 2-D orthogonal simulations
Parameters
Geometry
Cutting edge radius, r
Tool
Rake angle, α
Clearance angle, β
Workpiece
Workpiece length, l
Workpiece height, h
Depth of Cut, feed
Process
Length of Cut, loc
Cutting Speed, v
Width of cut
Coefficient of friction
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Material model for simulations of SiC
The DP yield criterion is given by
3.J 2  I1.    0
κ is given by

2. t . c
t c
Here, σt = H/2.2 and σc = H
For H=26 GPa, κ becomes 16.25 GPa.
J2 is given by
J2 

1
 1   2 2   2   3 2   3   1 2
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
For a uniaxial state of stress
I1   1
Thus J2 is given by
J2 
 12
3
This gives κ of 16.25 GPa and α of -0.375 .
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Simulations of edge turning
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Edge turning simulations of SiC
Variable Definition
Value
tool cutting edge radius
50 nm
tool rake angle
0º & -45º
tool clearance angle
5º & 50º
In-feed/uncut chip thickness
(50, 100, 250, 300, 500) nm
work piece velocity
0.05 m/s
Width of cut
250 µm
Workpiece-Tool geometry
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Simulation with achieved depth of approx. 220 nm
Note the deflection of workpiece material
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Results from edge turning simulations, 0º rake, 5º clearance
6.00
Cutting Force (N)
6.00
Experiment
Simulation
3.65
4.00
2.00
1.25
0.45
1.00
0.30
0.00
100
300
500
Depth (nm)
12
Results from edge turning simulations, 0º rake, 5º clearance
Thrust Force (N)
6.00
Experiment
Simulation
4.00
2.50
1.75
2.00
0.61
0.90
1.90
1.00
0.00
100
300
500
Depth (nm)
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Results from edge turning simulations, -45º rake, 5º clearance
12.0
Cutting Force (N)
10.0
Experimental
10.2
Simulation
8.0
6.0
4.0
2.3
2.0
2.3
1.5
0.0
50
250
Depth (nm )
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Results from edge turning simulations, -45º rake, 5º clearance
20.0
19.1
Experimental
Simulation
Thrust Force (N)
16.0
12.0
9.0
8.0
5.0
4.8
4.0
0.0
50
250
Depth (nm )
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Simulations of plunge cutting experiments
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2-D plunge cutting simulations of SiC
• Using a flat nose tool, machining was performed across the
wall thickness of a tube of polycrystalline SiC.
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Parameters for plunge-cutting simulations of SiC
Parameters
Tool
Workpiece & Process
Value
Unit
Cutting edge radius, r
50.0
nm
Rake angle, α
-45.0
deg
Clearance angle, β
11 & 0
deg
Workpiece length, l
3.0
µm
Workpiece height, h
1.0
µm
24.0
nm
Width of cut
3.0
mm
Length of Cut, loc
2.0
µm
Cutting Speed, v
5.0
m/s
coefficient of friction, COF
0.1
-
(Actual ) Depth of Cut, doc
Geometry
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Simulation with achieved depth of 25 nm
Note the deflection of workpiece material
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Results from simulations of SiC
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Flycutting experiment
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Flycutting experiment setup
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Force results from flycutting of SiC
• 4 distinct cuts made
• First cut overlapped 6 times
• Significant noise generated towards end of the experiment
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Results from flycutting of SiC
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Results from cut 1, cut 2 & cut 3
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Results from cut 4
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Simulations of flycutting
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Simulations of flycutting experiments
Method A
Parameters
Value
Unit
Tool
Workpiece & Process
Cutting edge radius, r
40.0
nm
Rake angle, α
-45.0
deg
Clearance angle, β
5
deg
Workpiece length, l
20.0
µm
Workpiece height, h
7.5
µm
In-Feed, feed
61 & 75
nm
Length of Cut, loc
15.0
µm
Cutting Speed, v
0.518
m/s
Friction factor
0.1
Geometry
-
Method B
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Results of simulations, Method A
Experiment
Simulation
Normalized force (N/mm^2)
1.40E+11
1.20E+11
1.16E+11 1.19E+11
1.17E+11
1.02E+11
1.00E+11
8.00E+10
6.00E+10
4.00E+10
2.00E+10
0.00E+00
61 nm
75 nm
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Results of simulations, Method B
3.000E+11
Experiment
Simulation
2.47E+11
Normalized force (N/m^2)
2.500E+11
1.99E+11
2.000E+11
1.500E+11
1.162E+11
1.018E+11
1.000E+11
5.000E+10
0.000E+00
61 nm
75 nm
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3-D scratching simulations
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3-D scratching simulations
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Setup for 3-D scratching simulation of SiC
Parameters
Value
Unit
Programmed Depth (feed)
125
nm
Actual depth, doc
103
nm
Length of Cut, loc
10.0
µm
Cutting Speed, v
0.305
mm/s
Friction factor, µ
0.1, 0.26, 0.6
-
Geometry
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Scratching simulations of SiC
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Results from simulation of SiC
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Summary of results
• Summary of 2-D orthogonal machining simulations
– Simulations agree with experiments for depths close to
100 nm and below.
– Pressures at the tool-workpiece interface are greater than
the hardness of the material for these depths.
– Workpiece deflection leads to actual depth being smaller
than the programmed depth.
• Summary of 3-D scratching simulations
– SiC simulations show thrust forces in good agreement
with the experiment.
– SiC simulations show cutting forces that are not in very
good agreement with the experiment.
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Conclusions
• Two types of simulations have been presented: 2-D & 3-D
– 2-D orthogonal simulations of SiC produce useful results
for depths at or below the DBT depth of the material.
– 2-D simulations create pressures at the tool-workpiece
interface that are in agreement with what is expected from
the experiments.
– 3-D scratching work shows encouraging results for initial
attempts at simulations of ceramic materials for depths
below the DBT depth of the materials.
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Recent Related Work
• Validation of material models.
• Development of analytical model to predict actual depth of
cut for a programmed depth of cut for each material
• Predicting behavior of ceramic materials under the brittle
mode.
• 2-D flycutting simulation using VAM.
• Current effort: 3-D turning simulations using round nose
cutting tools.
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Acknowledgements
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National Science Foundation for the research grant
Andy Grevstad and Third Wave Systems for software support.
Jeremiah Couey and Dr Eric Marsh at Penn State University.
Dr Guichelaar for equipment at the Tribology lab.
Lei Dong at University of North Carolina at Charlotte.
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Questions and suggestions
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Results from edge turning simulations, -45º rake, 50º clearance
6.00
6
Experiment
Cutting Force (N)
Simulation
3.65
4
2.30
2
1.7
1.45
0.9
1.25
1.23
0
50
100
300
500
Depth (nm)
42
Scratching simulation of Si
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Results from scratching simulation of Si
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