Shell Cracking in Investment Casting with Laser Stereolithography Patterns

This paper presents an investigation of ceramic shell cracking during the burnout process in investment casting with internally webbed laser stereolithography patterns. We hypothesize that shell cracking will occur when the rupture temperature of the ceramic shell is lower than both the glass transition temperature of the pattern material and the web· link buckling temperature. The hypothesis is validated by our experimental observations which confirm the numerical predictions from our finite element analysis. This provides a basis for design of the internal web geometry of a lithography pattern and evaluation of the burnout process with such a pattern. We show the shell cracking and weblink buckling temperatures to be functions of the pattern geometry (including the cross-sectional dimensions and span length of the web link) and the shell thickness