Abstract-The article describes a technique to calculate the reliability of a fixing element of a metal-polymer insert of a combined mold for casting products from thermoplastics. To do this, the stress-strain state of the metal-polymer fixing element is calculated by the force of ejection. The characteristics of ejection systems intended for removing molded products from a mold are given. The scheme for removing the product from the punch of a metal-metal-polymer mold, as well as the pressure distribution scheme for the metal-polymeric part of the die punch of the shrink-formed product, is shown. An algorithm is given for calculating the ejection force required to remove a mold from a punch. A special case of the ejection force for an "asterisk" product is calculated. The technique for obtaining the initial data for the calculation is described, in particular, the measurement of the change in the geometry of the article, subject to shrinkage of its material, was carried out using CAD simulation. By the example of the metal-polymer forming part of the mold for the star-shaped product, the reliability of the metal-fixing element in the cage was tested using finite element analysis. Calculations of the stress state of the metal-polymer insert for the "star" product are given. The article specifies a particular problem of finding stress concentrators in a metal-polymer insert, which allows designers to decide on the optimal shape and location of the fixing element. Finite element analysis is carried out using a free application FreeCAD, which enables one to accomplish the task. A step-by-step calculation algorithm in FreeCAD is presented with the description of built-in modules used in the calculations. A technique is proposed to calculate the reliability of a fixing element of a metal-polymer part of a mold for any design of a metal-polymer insert, provided that the design model is parameterized.

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