A COMPUTER-AIDED OPTIMIZATION APPROACH FOR THE DESIGN OF INJECTION MOLD COOLING SYSTEMS

A methodology is presented for the design of optimal cooling systems f or injection mold tooling which models the mold cooling as a nonlinear constrained optimization problem. The design constraints and objectiv e function are evaluated using Finite Element Analysis (FEA). The obje ctive function for the constrained optimization problem is stated as m inimization of both a function related to part average temperature and temperature gradients throughout the polymeric part. The goal of this minimization problem is to achieve reduction of undesired defects as sink marks, differential shrinkage, thermal residual stress built-up, and part warpage primarily due to non-uniform temperature distribution in the part. The cooling channel size, locations, and coolant flow ra te are chosen as the design variables. The constrained optimal design problem is solved using Powell's conjugate direction method using pena lty function. The cooling cycle time and temperature gradients are eva luated using transient heat conduction simulation. A matrix-free algor ithm of the Galerkin Finite Element Method (FEM) with the Jacobi Conju gate Gradient (JCG) scheme is utilized to perform the cooling simulati on. The optimal design methodology is illustrated using a case study.