Abstract
The object this report is to investigate the cause of the scab, rattail and veining in natural sand mold. In this report, it was investigated how the pouring rate, mold-hardness and number of gate give effects on the green and hot-properties of mold and the occuring of the scab.
The conclusion about these are as follows:
1) In natural sand mold, the longer the pouring lasts, the more severe the scab is.
2) In natural sand mold, the mold-hardness influences to its green-properties severely, but not so much to hot-properties. The hot-expansion and hot-strength increase a little with increasing in mold-hardness.
3) The higher mold-hardness is, the more severe the scab in natural sand mold becomes.
4) The relation between the number of gate and scab in natural sand mold has to be sought after the fundamental investigation about the occuring of scab is performed.
