High performance cooling system of the die cast dies

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

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

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

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

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.

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

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

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

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)

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

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

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.

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

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

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

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

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

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

High performance cooling system of the die cast dies Questions?