| The cooling process plays an important role in the quality and performance of the products in injection molding, The temperature is the most important process parameters in injection cooling process. Temperature and temperature distribution which is unreasonable may cause product defects and influence productivity. Therefore, how to accurately analyze the cooling process becomes extremely important. However, when people research the cooling process of injection molding in the past, they often thought that molds and products were close contact in the cooling process. In fact, polymer melt which was very hot will shrink while it is cooling. Resulting in reduced volume of injection molded part, a gap will be produced between the cavity and the surface of the part. The thermal contact resistance (TCR) will appear in the interface of the mold and the part when they were cooled. It will impact on the analysis results if the thermal contact resistance is ignored. In this paper,,The auther considered the part and mold as a whole while dealing with this issue and presumed that the part and mold was close contact all the time, but the thermal contact resistance was not ignored. In this paper, using the basic knowledge of the heat transfer, one-dimensional analytical solution of transient heat conduction equation was obtained when deal with the cooling question of a flat plastic parts.It also obtained the formula of the cooling time of the problem. Then it was extended to a simple two-dimensional, three-dimensional case. Furthermore, on the analysis of injection molding cooling process, control equation of three-dimensional mathematical model about the cooling process was derived. Finally, examples of simulation analysis shows that, the cooling process in the mold temperature changes while considering the thermal contact resistance. The cooling time was increased when TCR was existed. It also find that it was more serious when the thinner part was cooled.
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