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Dynamic Testing of Green Sand


Can metalcasters better monitor sand properties by adopting additional testing methods? SAM RAMRATTAN AND MO KHOSHGOFTAR, WESTERN MICHIGAN UNIVERSITY, KALAMAZOO, MICHIGAN; AND HIROYASU MAKINO, SINTOKOGIO LTD., AICHI, JAPAN


of these current tests do not provide as timely results as desired, but certain laboratory tests are essential in properly controlling processes. Due to the nature of the variables that are being monitored, some test data, such as loss on ignition (LOI) values, tend to change slowly, while other test results, such as green compression strength and compactabil- ity, may fluctuate more abruptly. Current sand testing provides insight into sand quality, but the metalcasting industry as a whole would benefit from methods to better and more quickly quantify the


S


and property testing tells a metalcasting facility how well it is controlling its green sand system. Many


effectiveness of sand-clay bond strength in green sand molds. Research was conducted to deter- mine if a metalcasting facility could improve its monitoring of clay and moisture levels in green sand with non-standard testing methods, such as a thermal erosion test (TET) and modified cone jolt toughness test. Using both ambient and elevated- temperature testing procedures may potentially provide metalcasters with more relevant information about green sand system control.


Methodology & Preparation All green sand data was generated


in Western Michigan Univ.’s Metal


Casting Laboratory. Physical, mechan- ical, and dynamic measurements were taken on the samples using a number of common testing procedures, though the major focus was on the thermal erosion test and modified cone jolt toughness tests. Metalcasting facilities often use


additives to solve green sand problems such as flow. Additives can affect the sand, such as waterproofing the clay. Te researchers kept the bonding formulation simple to reduce potential errors in preparing the green sand batch and simplifying the analysis. Apart from sand, clay and water, no additives were introduced to the green sand systems. Te five bentonite clays


Fig. 1. The wet tensile strength (at 300C for 30 seconds) of systems A and B are shown as compactability increased.


36 | MODERN CASTING September 2015


Fig. 2. The friability of systems A and B are shown as compactability increased.


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