1. High performance cooling system of the die cast dies

2. High performance cooling system of the die cast dies
Objectives: 1. Improve performance of the die cast die cooling system 2. Reduce soldering of the die components 3. Reduce solidification shrinkage defects 3. Improve micro-structure of the casting

3. Typical cooling system layout
High performance cooling system of the die cast dies
Typical cooling system layout

4. Stages of the boiling process
High performance cooling system of the die cast dies
Stages of the boiling process
Convective heat
transfer mode
Steam jets
are forming
Neighboring vapor
jets merge
Nucleate boiling
Most of the surface of the
heated wall is covered with
vapor

5. Heat transfer coefficient distribution along the channel length
High performance cooling system of the die cast dies
Heat transfer coefficient distribution along the channel length
Zone I Convection heat transfer
Zone II Nucleate boiling
Zone III Most of the surface of the heated wall is covered with vapor
Zone IV Transition boiling
Zone V Film boiling

6. High performance cooling system of the die cast dies
There are substantial differences between the two phase flow in micro-channels and conventional cooling channels 1. Surface tension force has a more pronounced influence on the flow. 2. Bubbly flow can be rarely observed because bubbles grow and quickly reach size of the channel. 3. Due to small size of the channel Taylor instability doesn’t occur in the micro-channels.

7. Boiling in thin channel
High performance cooling system of the die cast dies
Boiling in thin channel
Zone I Convection heat transfer
Zone II Nucleate boiling
Zone III Most of the surface of the heated wall is covered with vapor
Zone IV Transition boiling
Zone V Film boiling

8. High performance cooling system of the die cast dies
Full shot with core

9. Core with micro-channel cooling
High performance cooling system of the die cast dies
Core with micro-channel cooling

10. Stress analysis of the core(dyne/cm^2)
High performance cooling system of the die cast dies
Stress analysis of the core(dyne/cm^2)

11. Temperature distribution in the core (Before spray)
High performance cooling system of the die cast dies
Temperature distribution in the core (Before spray)

12. High performance cooling system of the die cast dies
Core after 6,000 shots
Old cooling channel design
Micro-channel cooling design

13. High performance cooling system of the die cast dies
Heat transfer coefficient for micro-channel cooling Heat transfer coefficient is found by a superposition of the nucleate boiling and forced convection components1.
Where,
S suppression factor
hnb - nucleate boiling heat transfer coefficient
F enhancement factor
hsp - single phase heat transfer coefficient
1. J.C. Chen, Correlation for boiling heat transfer to saturated fluids in convective flow, Industrial and Engineering Chemistry – Process Design and Development5 (3) (1966) 322–329.

14. Verification of the numerical analysis results
High performance cooling system of the die cast dies
Verification of the numerical analysis results

15. Smaller core with cooling (Dia. 12 mm)
High performance cooling system of the die cast dies
Smaller core with cooling (Dia. 12 mm)

16. Smaller core with cooling (Dia. 12 mm)
High performance cooling system of the die cast dies
Smaller core with cooling (Dia. 12 mm)

17. Rib insert with micro-channel cooling
High performance cooling system of the die cast dies
Rib insert with micro-channel cooling

18. High performance cooling system of the die cast dies
Old cooling line design
Micro-channel cooling

19. Conclusions High performance cooling system of the die cast dies
Three dimensional micro-channel cooling is an affective high capacity thermal management method. It can support high heat transfer rates from the liquid metal during metal flow and solidification.
Reduction in core heat resistance as well as increase of thermal capacity of the cooling system, allows support of higher heat flux without over-heating of the core
New cooling design concepts allowed further reduction or even elimination of die soldering, casting surface defects, and excessive external cooling while reducing cycle time and cost

20. High performance cooling system of the die cast dies
Questions?