3. Results
3.1. Tensile load on the casting and the contraction of the casting
during cooling in the green sand mold
Fig. 2 shows the results of the tensile load on the castings and
the contractions of the castings in the green sand molds. The tensile
loads on the castings arose for each flange condition immediately
after the expansion at the beginning of the solidification had ended.
The average expansion observed in the experiments was 0.06mm.
This expansion is likely attributable to gas evolution during solidification
(Eskin and Katgerman, 2007; Awano et al., 1992). The
maximum tensile load on the casting with the flange during the
measurement was 729N (Fig. 2(a)), which corresponded to a total
contraction of 6.26mm. In this study, the total contraction was
defined as the contraction from the temperature at the maximum
expansion to 45 ◦C. Fig. 2(b) shows the results for the flangeless
casting in the green sand mold. The maximum tensile load on the
casting during the measurement was 265 N. Although the flangeless
casting lacked a flange, a relatively low tensile load was
measured on the casting. This result could be because of the friction
that existed between the casting and the green sand mold and/or
the reaction force that occurred between the dumbbell portion of
the casting and the metal molding box. The total contraction was
6.25mm for the flangeless casting. The total contractions of the
flangeless and flange castings (Fig. 2) were nearly the same as for
the green sand mold.