Direct fabrication of IC sacrificial patterns via rapid prototyping approaches

Abstract

Patterns made from conventional wax materials in the Investment Casting (IC) process can easily be distorted, damaged, or broken in transportation or routine handling or due to exposure to heat. Alternatively, the strength and toughness of most Rapid Prototyping (RP) materials virtually eliminates this drawback due to their resistance to heat, humidity, and post curing. The current study is conducted to investigate the feasibility of using RP processes such as FDM and MJM to fabricate IC patterns from Acrylonitrile Butadine Styrene (ABS) and acrylate based materials respectively to be used directly in IC process. Evaluation of the effects of different internal pattern designs of the RP parts are conducted based on the thermal analysis approach and burnout properties of the RP patterns. Ceramic shell molds are fabricated on both RP patterns and subsequently placed in an oven which is gradually heated to 1000°C. The decomposition temperature and the residual ash of the RP pattern materials is determined and analyzed. Results show that the acrylate pattern ofMJMdecomposes rapidly compared to the ABS pattern from the FDM process. It is also observed that quasi and square hollow internal structures show better collapsibility or burnout properties, with no cracks, compared to cross pattern and cross hatch designs.