模具排气设计是否合理也是决定模具精度保持的一主要因素。精密制品多数是使用工程塑料成型，在成型过程中为了保证塑料良好的流动性以及塑料分子收缩的一致性一般要求模温在一定范围才能成型。当模具温度过高，模具配件因为膨胀会导致模内的气体排出困难，造成产品出现困气、烧焦、缺料等不良现象，因此模具的型腔部分设计要多使用镶嵌配件，顶出配件在磨擦面要设计排气槽防止烧针现象。
Whether the design of die exhaust is reasonable or not is also a main factor to determine the accuracy of die. Most of the precision products are made of engineering plastics. In order to ensure the good fluidity of plastics and the consistence of plastic molecular shrinkage, the mold temperature is generally required to be within a certain range. When the mold temperature is too high, the expansion of the mold parts will lead to the difficulty of exhausting the gas in the mold, resulting in the poor phenomena such as trapped gas, burning, lack of material and so on. Therefore, the design of the mold cavity should use more inlaid parts, and the exhaust slot should be designed on the friction surface of the ejected parts to prevent the burning of the needle.
合理地设计精密注塑模具是获得精密制品的基础和必要前提。通过合理地确定模具的尺寸与公差、采取防止注塑制品产生收缩率误差、注塑变形、脱模变形、溢边等，以及确保模具精度等技术措施，并采用正确的精密注塑工艺、适用的工程塑料材料和精密的注塑设备，使之达到最佳的匹配，对于提高精密塑料件的质量、可靠性和性能，降低生产成本，提高生产效率具有十分重要的意义。
Reasonable design of precision injection mold is the basis and necessary prerequisite for obtaining precision products. Through reasonably determining the dimension and tolerance of the mold, taking technical measures to prevent the shrinkage error, injection deformation, demoulding deformation and edge overflow of the injection molded products, as well as to ensure the accuracy of the mold, and adopting the correct precision injection molding process, applicable engineering plastic materials and precision injection equipment, to achieve the best matching, it can improve the quality and reliability of the precision plastic parts It is of great significance to reduce production cost and improve production efficiency.