Abstract

Beyond simply identifying   shrinkage   porosity   and filling   problems,   numerical  tools  have   been   further developed  to  predict  stresses,  microstructures,  defects and   to   model   specific   processes   that   can   be   used effectively   by   the   foundry   engineer   early   in   the manufacturing process to save significant time and cost. More specifically this paper will address the following topics:
•Stress and deformation - what is the final shape of
the cast component? What about fatigue life of the die?   Can   heat   transfer   variation   due   to   gap formation between the casting and the die be taken into account? Can hot tears defects be predicted?
•Micro  and  gas  porosity  -  what  about  the  integrity
of   the   part?   Can  porosity  be  compensated   by graphite   expansion?   What   about  the  initial  gas content in the liquid?
•As-cast mechanical properties-can local
mechanical  properties  be  predicted  such  as  yield strength and hardness?

Keywords

FEM,   casting   simulation,   stress,   deformation,   gas porosity, microstructure, mechanical properties, graphite expansion, ProCAST, QuikCAST.

Introduction

With the generalization of CAD 3D design, the increase of computing performance and now almost 20 years of experience  in  casting  modelling,  foundry  simulation software have reached a state where a relevant input for the  design  of  a  die  or  a  mould  can  be  given  to  the process  engineers.  Gating  systems,  overflows,  venting channels,   risers   can   be   optimized   using   numerical simulation.  Solidification related  defects  like hot spots can  also  be  predicted  taking  into  account  chills  or  die cycling   so   as   to   accurately   reproduce   production conditions.

Today,  most  of  the  casting  simulation  packages  in the market  can  handle  solidification  and  fluid  flow  in  the casting    with    satisfactory    accuracy.    However,    the foundry  industry  wants  to  focus  on  more  advanced predictions such as stress  and deformation, microstructure determination, as-cast  mechanical properties and microporosity indication.