Abstract
Chemically bonded sand cores and molds are more commonly referred to as precision sand systems in the high production automotive powertrain sector. Their behavior in contact with molten metal can lead to casting defects. Consequently, the interaction is of great interest and an important part of metal casting technology. The American Foundry Society (AFS) sand testing is based on physical, mechanical, thermal and chemical properties of the sand system. Foundry engineers have long known that certain AFS sand tests provide limited information regarding control of molding and casting quality. The inadequacy is due to the fact that sand casting processes are inherently thermo-mechanical, thermo-chemical and thermo-physical.
Non-standard foundry sand testing has proven useful for laboratory measurement of these characteristics in foundry sand using a disc-shaped specimen. Similarly, the equivalent disc-shaped specimens are used for casting trials. In order to accomplish near-net-shape casting with minimal defects, it is necessary to understand both the properties of the sand system, as well as the interface of molten metal when different binders, additives and/or refractory coatings are used. The methodology for the following non-standard chemically bonded sand tests is described: (1) disc transverse; (2) impact; (3) modified permeability; (4) abrasion; (5) thermal distortion; (6) quick loss on ignition. The data related to the non-standard sand tests were analyzed and interpreted. The test results indicate that there is relatively lower test-to-test variability with the disc-shaped specimens. The non-standard tests were able to discriminate between the chemically bonded polyurethane cold box sand specimens. Further studies should be conducted on various other sand and binder systems as well as on different specimen thicknesse
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Male, Ph. D., Professor. His area of specialization is materials & processes emphasizing casting processes. He is a member of the 4F and 4H Research Committees at the American Foundry Society (AFS), and a Key Professor for the Foundry Educational Foundation (FEF). He has published more than two hundred technical papers and has been awarded several patents. His current research projects involve casting issues at the mold/metal interface, aeration sand systems, and new tests for foundry sands.
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Ramrattan, S. Non-standard tests for process control in chemically bonded sands. China Foundry 13, 59–66 (2016). https://doi.org/10.1007/s41230-016-5118-7
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DOI: https://doi.org/10.1007/s41230-016-5118-7