般情况下，精密铸造件尺寸精度是受铸件结构、铸件材质、制模、制壳、焙烧、浇注等多方因素影响的，其中任何一个环节设置、操作不合理都会使铸件的收缩率产生变化，导致铸件尺寸精度与要求有偏差。以下是可造成精密铸件尺寸精度缺陷的因素：
In general, the dimensional accuracy of precision castings is influenced by various factors such as casting structure, casting material, mold making, shell making, roasting, pouring, etc. Any unreasonable setting or operation of any link can cause changes in the shrinkage rate of the casting, resulting in deviations from the required dimensional accuracy of the casting. The following are factors that can cause dimensional accuracy defects in precision castings:
（1）铸件结构的影响：a. 铸件壁厚，收缩率大，铸件壁薄，收缩率小。 b. 自由收缩率大，阻碍收缩率小。
(1) The influence of casting structure: a The casting wall thickness has a high shrinkage rate, while the casting wall thickness has a low shrinkage rate. b. The free shrinkage rate is high, while the obstructed shrinkage rate is low.
（2）铸件材质的影响：a. 材料中含碳量越高，线收缩率越小，含碳量越低，线收缩率越大。 b. 常见材质的铸造收缩率如下：铸造收缩率K=(LM-LJ)/LJ×100%， LM为型腔尺寸，LJ为铸件尺寸。K受以下因素的影响：蜡模K1、铸件结构K2、合金种类K3、浇注温度K4。
(2) The influence of casting material: a The higher the carbon content in the material, the smaller the linear shrinkage rate, and the lower the carbon content, the larger the linear shrinkage rate. b. The casting shrinkage rate of common materials is as follows: casting shrinkage rate K=(LM-LJ)/LJ × 100%, where LM is the cavity size and LJ is the casting size. K is influenced by the following factors: wax mold K1, casting structure K2, alloy type K3, and pouring temperature K4.
（3）制模对铸件线收缩率的影响：a.射蜡温度、射蜡压力、保压时间对熔模尺寸的影响以射蜡温度明显，其次为射蜡压力，保压时间在保证熔模成型后对熔模终尺寸的影响很小。 b.蜡(模)料的线收缩率约为0.9-1.1%。 c.熔模存放时，将进一步产生收缩，其收缩值约为总收缩量的10%，但当存放12小时后，熔模尺寸基本稳定。 d.蜡模径向收缩率仅为长度方向收缩率的30-40%，射蜡温度对自由收缩率的影响远远大于对受阻收缩率的影响(佳射蜡温度为57-59℃，温度越高收缩越大)。
(3) The influence of mold making on the linear shrinkage rate of castings: a The influence of wax injection temperature, wax injection pressure, and holding time on the size of the investment mold is significant with wax injection temperature, followed by wax injection pressure. Holding time has little effect on the final size of the investment mold after ensuring its formation. b. The linear shrinkage rate of wax (mold) material is about 0.9-1.1%. c. When the investment mold is stored, further shrinkage will occur, with a shrinkage value of about 10% of the total shrinkage. However, after 12 hours of storage, the size of the investment mold is basically stable. d. The radial shrinkage rate of wax molds is only 30-40% of the longitudinal shrinkage rate, and the effect of wax injection temperature on the free shrinkage rate is much greater than that on the hindered shrinkage rate (the optimal wax injection temperature is 57-59 ℃, and the higher the temperature, the greater the shrinkage).
