The use of specialty sand blends to improve casting quality and reduce costs
Blends, Chromite, Metal penetration, Silica sand, Steel casting defects, Veining, Zircon
71st World Foundry Congress: Advanced Sustainable Foundry, WFC 2014
Metal casters continually strive to produce the highest quality castings at the lowest competitive cost. Unfortunately they have little control of the cost of the required materials. It's been well established that molding materials such as chromite, zircon, and mullite all exhibit low expansion leading to fewer casting defects related to expansion and better dimensional accuracy. They also have refractory values significantly higher than silica sands. Although some casting applications require the use of 100% specialty sands, there is a significant amount that requires only modest improvements to the properties of silica sand to yield significant casting quality benefits. The present research studies the high temperature physical properties of various blends of Silica sand with Zircon and Chromite sands and defines physical characteristics including expansion, phase transformations, high temperature viscosity and specific heat capacity. The various blends are then evaluated for performance with the use of standard test castings. The test casting used indicates the dimensional stability of the material bends and the dimensional accuracy improvements possible. The research indicates that major advantages are seen in the reduction of expansion and refractory failure related defects. The paper describes characteristics of silica, specialty and sand blends and correlates material properties to quality improvements in defects and dimensional accuracy. The information generated during the research is then used in to provide material dataset information for casting simulation. These simulations are compared and validated using the test casting results to close the loop of defining the causes and solutions to common casting defects. The paper suggest specialty sand levels for several casting applications based on alloy type and casting section size and provides a guide to selection of specialty sands. The research demonstrates the effectiveness of using blends of Silica sand with Zircon and Chromite in the metal casting industry to reduce costs while improving casting quality. Copyright 2014 World Foundry Organization.
Original Publication Date
Ravi, S. and Thiel, J., "The use of specialty sand blends to improve casting quality and reduce costs" (2014). Faculty Publications. 1431.