IMPROVING BUILD SPEED IN RAPID FREEZE PROTOTYPING THROUGH INCREASE OF HEAT TRANSFER

摘要

The heat transfer in the Rapid Freeze Prototyping (RFP) process has been significantly increased for improvement of build speed. RFP is a solid freeform fabrication process in which water droplets are deposited and solidified layer-by-layer to form three-dimensional ice patterns for investment casting. Mechanisms have been devised to cool the substrate to as low as -140 ℃. Chilling plates were developed to enable effective transfer of heat with the aid of conduction. To ensure that the deposited water does not freeze to the chilling plate, various surface coats were investigated. The most effective interface material was identified using contact angles measured with high resolution digital photography. The experimental results were substantiated with simulations performed using Fluent. The improvements in build speed after incorporating the above changes were measured to verify the trends predicted from the simulations.