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Fig. 8. Shown is a microscopic view of the Biasill aggregate.


Fig. 9. A control casting made with olivine sand (left) is dis- played next to a casting made in 100% Biasill sand (center) and a casting made with Biasill used as the mold facing sand.


As with Green Diamond and silica


sand, Biasill has shown that it can be incorporated into a company’s sand system with the existing olivine sand.


After Replacement No clear patterns have emerged


for types of metalcasting facilities gravitating toward one new aggregate over another. LaFay stresses that each option has proven to work seamlessly with existing olivine sand systems and


encourages metalcasters to investi- gate their options—all of which have recently been the subject of technical research—with their sand supplier. “Te selection of an aggregate is


unique,” he said. “Many times it is based on the quantity of aluminum and brass poured in a combination facility, or whether it is aluminum-


only or brass-only. And casting configuration is everything. Its level of intricacy will have a bear- ing. It also has to do with the green sand molding techniques of the foundry and the measurement of those characteristics.” While some metalcast-


ers may be sitting on a pile of olivine sand they hoarded when word got out of limited availability,


they are likely only delaying an inevitable transition to an alternative aggregate. “Olivine sand is a forgiving sand, so


metalcasters will have to ramp up their sand testing for a little bit during the transition to understand how the changes go,” Morrison said. “It will be a little bit more upfront work, but once they get there, they are going to be okay.”


24 | MODERN CASTING December 2012


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