1.
NUMERICAL MODELING IN
COPPER BILLET CASTING
Ioannis Contopoulos, ELKEME
Numerical Modeling Department 1

2.
ELKEME
• The R&D Center of VIOHALCO
• Founded 1999
• Industrial research, technological
development and analysis of
–Aluminum
–Copper
–Steel
–Zinc
Lab/Section Name 2

3.
ELKEME
• Applied technology research towards
– Quality Improvement of existing products
– Development of new, innovative, high added
value products
– Optimization of Industrial Processes
• Energy and cost efficiency
• Health and safety
• Environment and sustainable growth
Numerical Modeling Department 3

4.
ELKEME
• State of the art laboratories
• Highly capable scientists, engineers,
technicians
• Continuous professional development
• Collaborations with External Laboratories
• Research projects in Metallurgy, Material
Sciences and Environmental Engineering
• Build knowledge and competence network
Numerical Modeling Department 4

5.
ELKEME
• Long term relationships with academic and research
institutes (National Tech. Univ. of Athens, Universities of
Patras, Ioannina, Delft, Ghent, Manchester)
• Supervision of Diploma/Master’s/PhD theses
• Student training programs
• Seminars
• International collaborations
• Participation in international scientific/engineering
associations
• Contributions to scientific journals and conferences
(ICEFA, ICAA, ICEAF, Thermec, TMS, etc.)
Numerical Modeling Department 5

6.
100
120
140
160
180
200
220
-7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7(mm)
ΗV1.0
1

7.
Numerical Modeling Department 10
Process
Metallurgy
Physical
Metallurgy &
Forming
Corrosion
Environmental
Metallography &
Electron Optics
Mechanical
Testing &
Manufacturing
Technology
Numerical
Modeling
Surface Science
& Coatings
Analytical
Chemistry

8.
ELKEME Numerical Modeling
13Numerical Modeling Department

9.
14
ELKEME Numerical Modeling
• Software:
– ANSYS Workbench
• Design Modeler
• Meshing
• Fluent (FV)
• Mechanical Enterprise (FE)
– Design Explorer
– AQWA
• 2 HPC
• Maxwell 2D
Numerical Modeling Department

10.
Numerical Modeling Department 15

11.
NUMERICAL MODELING IN
COPPER BILLET CASTING
Ioannis Contopoulos, ELKEME
Numerical Modeling Department 17

12.
Numerical Modeling
• Deeper understanding of process
• Virtual variation of operation parameters
• Assists in
– Identifying critical process parameters
– Optimizing production process
– Improve productivity
Numerical Modeling Department 19

13.
Numerical setup
• ANSYS Fluent 12.0/16.2, solidification model
• Double precision, axisymmetric, 1mm mesh resolution
• Geometry: mold, distributor, air gap, water curtain
• Insulated top (graphite flux)
• DHP Copper physical properties (thermal properties,
solidification properties: latent heat, liquid fraction,
porosity)
– No thermal shrinking
– No micro/macro solute segregation
• Casting speeds: A→1.15A→1.20A→…
• Various cooling setups
Numerical Modeling Department 20

14.
Numerical problems
• The simulation of casting is a very difficult
numerical problem. The fast transition from the
liquidus to the solidus temperature (energy
release-latent heat, viscosity transition from liquid
to solid) makes the equations very “stiff”: small
changes lead to instabilities and to the destruction
of the solidification front
• It is very difficult to find a convergent solution
• Unless one finds a convergent solution, one must
not trust the small details of the final result
Numerical Modeling Department 21

15.
Numerical problems
• We tried many different numerical
approaches
• We were able to obtain convergent
solutions that we can trust!
Numerical Modeling Department 22

16.
Numerical grids
Numerical Modeling Department 23

17.
air gap
distributor
water curtain mould: ΔΤwater=+1 oC

18.
air gap
distributor
water curtain mould: ΔΤwater=+1 oC

19.
air gap mould
distributor
water curtain

20.
3D phi-periodic (8 inlets)
Numerical Modeling Department 27

21.
3D asymmetric installation
Hotter side
Numerical Modeling Department 28

22.
3-D periodic simulation: Corellation between casting speed and
liquid pool depth
490
500
510
520
530
540
550
560
125 130 135 140 145 150 155
Casting Speed (mm/min)
LiquidPoolDepth(mm)
91kW
136kW
181kW
Linear (91kW)
Linear (136kW)
Linear (181kW)
Numerical Modeling Department 29
Low Medium
Casting Speed
High

23.
3-D periodic Simulation: Correlation between casting speed and
primary cooling zone width
0
5
10
15
20
25
30
35
40
45
125 130 135 140 145 150 155
Casting Speed (mm/min)
Primarycoolingzonewidth(mm)
91kW
136kW
181kW
Linear (91kW)
Linear (136kW)
Linear (181kW)
Numerical Modeling Department 30
Low Medium
Casting Speed
High

24.
Solidification rates
Numerical Modeling Department 31

25.
Primary Conclusions
• The original setup had limitations that did
not allow the increase of productivity
• Setup asymmetries
 Fix
Numerical Modeling Department 32

26.
Revisited problem 2015
• Basic factors related with productivity:
– Depth/Geometry of molten metal in mould
 Modifications
 Speed increase 15-20% !
 Need to go even faster!
• Setup asymmetries
 Fixed !
Numerical Modeling Department 33

27.
Preliminary results 2015
• The shape of the solidification front
consists of 3 parts:
1. The growing solidification front in the mold
2. An almost cylindrical front in the air gap
region below the mold
3. A V-shaped final solidification front in the
water curtain region
Numerical Modeling Department 34

28.
220mm air gap
155mm/min
Water cooled
mold
Air gap
Water curtain
Third part
Second part
First part Setup A

29.
220mm air gap
165mm/min
Water cooled
mold
Air gap
Water curtain
Third part
Second part
First part Setup B

30.
270mm air gap
165mm/min
Water cooled
mold
Air gap
Water curtain
Third part
Second part
First part Setup C

31.
220mm air gap
165mm/min
Semi-solidified
zone
Metalostaticpressure Zone of
slow solidification rate
Setup B

32.
Zone of
slow solidification rate

33.
Metalostatic pressure
required to fill
solidification shrinkage
porosity

34.
220mm air gap
165mm/min
Re-heated zone
prone to remelting
of eutectics
Setup B

35.
220mm air gap
165mm/min
Mold exit temperature
around 850-900oC
non uniform
air gap temperature
Setup B

36.
Conclusions
• The shape of the central solidification front
depends only on the casting speed
• The improvement IS NOT due to changes in
the shape of the front at the center
• Increased metalostatic pressure compensates
for solidification shrinkage porosity
• Thermo-mechanical investigation of cooling
beyond solidification
Numerical Modeling Department 44

37.
Conclusions
• Increasing the height of the air gap leads
to secondary problems due to very slow
solidification rates and/or remelting at
intermediate radii
• Future trials:
– Modified cooling
– Thermo-mechanical investigation with ANSYS
Mechanical
Numerical Modeling Department 45