A Study on Freezing of Molding Sand（Part 1） −Characteristics of frozen sand and its freezing behavior −

Results from the questionaire about the foundry shops in Hokkaido confirmed that great interest was focussed on the problem of freezing of molding sand. In the past no scientific research about this problem was performed， so fundamental experiments have been carried out to obtain the characteristics of frozen sand and its freezing behavior. Some interesting results were obtained and indicated that the characteristics of frozen sand should be positively utilized for casting mold in the future. They are as follows : 1）Frozen sand becomes harder than the natural one and stronger in compression and shearing. Permeability is also better than that of natural sand，especially in frozen sand before ramming. 2）In the cooling curve can be recognized the flat part which shows the interval of constant temperature. The length of this part becomes longer according to the moisture content and is changed by the kinds of constitution of molding sand. 3）Deformation of frozen sand rammed in the test piece shows an interesting behavior : expansion or contraction. This behavior is almost similar to that of hot heated sand