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鼠尾的形成是由于铸型型腔局部表面干砂层受热膨胀，当膨胀力大于滑移阻力时，干砂层产生了剪切滑移。滑移的阻力主要来自相邻的干砂层。阻力随干砂层长细比的增加而急剧减小。提高型砂的热强度，减少干砂层的长细比，能有效增加鼠尾产生的临界应力σｃ，有效防止鼠尾的产生。当千砂层长细比小于 １／２或热压应力不大于水分饱和凝聚区的湿压强度时，绝不可能产生鼠尾。
The formation of rat tail is due to the thermal expansion of the dry sand layer on the local surface of the mold cavity. When the expansion force is greater than the sliding resistance, the shear slip occurs in the dry sand layer. The slip resistance comes mainly from the adjacent dry sand layers. Resistance decreases sharply as the slenderness ratio of dry sand increases. Increasing the hot strength of the sand and reducing the slenderness ratio of the dry sand layer can effectively increase the critical stress σc generated by the tail of the rat and effectively prevent the occurrence of rat tail. When the sandshaling slenderness ratio less than 1/2 or hot compressive stress is not greater than the wet strength of the wet area of condensation strength, it is absolutely impossible to produce rat tail.