4. Conclusions
This report has examined the effects of extended fins on the heating/cooling efficiency of rotational
molding and the molded product qualities. Rotational molding experiments were carried out in a laboratory-scale uniaxial machine, which is capable of measuring internal air temperature in the cycle.
Three types of fins, including pin, rectangular and triangular fins, were used to mold the parts.
Cycle time reductions by the fins were measured. Characterization of molded part properties was also
performed after molding. It was found that the mold surface with pin fins exhibited the highest heating and cooling efficiency. The use of fins in rotational molding can be better justified under conditions for which the convective heat transfer is small. In addition, molds with extended surfaces produce parts with less shrinkage but greater warpage. The internal surface quality and tensile strengths of molded parts were not affected by these fins. It was shown that the heating/cooling efficiency can be increased by the extended fins, and this increase provides significant advantages in terms of reduced cycle time