Comparison of shrinkage, checking, and absorbed energy in impact bending of Korean ash squares dried by a radio-frequency/vacuum process and a conventional kiln.

Korean ash squares, 66 mm thick and 100 cm long, to be used for baseball bats were dried in a radio-frequency/vacuum (RF/V) kiln and a conventional kiln to compare drying times, shrinkage, checking, and absorbed energy in impact bending. RF/V drying time was shortened to approximately three-tenths of conventional kiln-drying time. Average drying rate in the RF/V kiln during the first 12 hours was fifteen times as fast as that in the conventional kiln. The shrinkage during the RF/V drying represents a reduction of almost 40 percent tangentially and 25 percent radially of the shrinkage observed in conventional kiln-drying. The ratio of tangential/radial shrinkage (T/R) in the RF/V drying process was lowered to approximately 1 ; T/R was 1.42 in the conventional kiln-drying process. Surface checks were quite slight in the RF/V kiln, while severe in the conventional kiln. Absorbed energy in impact bending of squares dried in the RF/V kiln was about 14 percent higher than that of squares dried in the conventional kiln.