Originally published in the July 2014 issue of Modern Casting.
The dilution of core sand and other additives into greensand is a popular topic of discussion in the metalcasting industry. In the 1960s and 1970s, industry experts debated whether core sand was a contamination in greensand. But core sand or other additives (new sand) are not considered contaminations because these materials are added into the greensand by design, not by accident. Today’s sand casting facilities treat core sand and new sand as an additive that is monitored, and it is adjusted to compensate for variations in the process.
The testing of greensand with core sand dilution and other additives is based largely on work from a variety of industry experts in the last 25 years. In that time, testing has come a long way. It can be a dynamic process that checks physical properties such as wet tensile strength, cone jolt toughness and friability. Additionally, the sand’s emission characteristics at pouring, cooling and shakeout can and should be evaluated. The influence of core sand and other additives affects the application of greensand in metalcasting facilities.
Recent developments in wet tensile strength, cone jolt toughness and friability have broadened the industry’s understanding of the influence of core sand and other additives. Still, a single test cannot be used to completely understand the influence of these additives. Instead, a combination of testing protocols has generated the greatest amount of information to support the application.
Common Greensand Tests
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