For testing of the cleavage strength, the standardized test specimen according to Fig. 1 with its cylindrical surface is placed between the shear plates of the strength testing device.
The cleavage strength can be read directly from the shear strength scale. The average value of three tests is authoritative for all strength tests, if the separate values do not deviate by more than ± 5% from the average value. With bentonite-bonded molding materials, it can be converted to the green tensile strength (Fig. 2). The relation is linear and the multiplier is 0.637. The quotient of cleavage strength/pressure can be used to represent the bonding capacity.
Mold sand testing