As casting geometries become thinner in design and more complex, the influences from resin selection will place a more crucial role in providing a solid casting. An aluminum foundry was experiencing issues with a dendritic type shrinkage defect that was related to a recent change in a resin package, resulting in higher scrap rates from the shrink defect.
The only variable that changed and created the dendritic type shrink defect in this case was the resin. HA-International designed an experiment to determine how PUCB resin percentages, and solvent packages used in urethane cold boxes affected the influence of shrink on this particular aluminum A316 casting during solidification.
Evaluation occurred on a newly developmental phenolic urethane cold box and a modified version of this new system, utilizing the latest solvent packages found in HAI's SigmaCure series of phenolic urethane cold box (PUCB). The experimental setup of the study included computer aided modeling, analytical testing, and actual casting tests to generate cooling curves. These results, in conjunction with the temperature dependent properties were used to create simulation model datasets for the cold box sand mix in order to simulate the actual sand mold physical properties and understand how it was creating the shrinkage defects. Between 1,500-2,000 design iterations were conducted in modeling software to obtain a dataset that matched the results from actual lab casting results. The specific heat capacity and density results required for the simulation datasets were measured directly using instrumentation on test molds.