A numerical framework for three-dimensional optimization of cooling channels in thermoplastic printed molds

The rapid progress of additive manufacturing (AM) technology in the last few decades has unlocked new potentials for the injection molding industry by enabling the quick and cost-efficient manufacture of molds with complex geometries Despite the wide literature regarding experimental investigations on AM polymer -based soft tools specifically produced to cope with low-volume production of small-sized injected parts, their lifespan remains uncertain, and premature failures are often related to poor thermal performance. This paper is devoted to the numerical study and enhancement of the heat transfer within a thermoplastic 3D printed insert with cooling channels (CCs). Experimental thermal characterization is performed on printed composite samples made of polycarbonate reinforced with carbon fibers, considered as tool material. The simulations are performed on an industrial case, thereby facilitating a comprehensive validation of the proposed framework. Parametric studies show a marked cycle time sensitivity to insert thermal conductivity within the 0.1-1.0 W/(mK) range while demonstrating negligible influence on cycle times for polymer-polymer thermal contact resistance values below 10-3 m2 K/W. Furthermore, to find a suitable arrangement of the CCs' layout, we propose here an accurate optimization methodology based on 3D overset meshes in the finite element method context coupled to the augmented Lagrangian particle swarm optimizer. The optimized bent CCs' configuration enhances part surface temperature uniformity by 42% and reduces its temperature delta by over 6 degrees C, all while employing 67% of the reference cycle time. The thermal shortcomings of the thermoplastic AM mold, compared to its steel counterpart, are also addressed in this work.

Automated summary

The rapid development of additive manufacturing technology in the past few decades has opened up new possibilities for the injection molding industry. This study focuses on the numerical study and enhancement of heat transfer in thermoplastic 3D printed mold inserts, as well as the comparison of their thermal performance with steel molds.