Application of new conformal cooling layouts to the green injection molding of complex slender polymeric parts with high dimensional specifications

Abstract

Eliminating warpage in injection molded polymeric parts is one of the most important problems in the injection molding industry today. This situation is critical in geometries that are particularly susceptible to warping due to their geometric features, as occurs with topologies of great length and slenderness with high changes in thickness. These features are, in these special geometries, impossible to manufacture with traditional technologies meeting the dimensional and sustainable requirements of the industry. The paper presents an innovative green conformal cooling system that is specifically designed for parts with slender geometric shapes, highly susceptible to warping. Additionally, the work presented by the authors investigates the importance of using highly conductive inserts made of steel alloys in combination with the use of additively manufactured conformal channels in reducing influential parameters such as warpage, cooling time and residual stresses in the complex manufacturing of long and slender parts. The results for a real industrial case study indicate that the use of conformal cooling layouts decreases cycle time by 175.1 s - 66% below the current cooling time, the temperature gradient by 78.5% specifically 18.16 ºC, the residual stress by 39.78 MPa or – 81.88 %, and the warpage by 6.9 mm or- 90.5%. In this way, it is possible to achieve a final warping in the complex geometry studied of 0.72 mm under the maximum value required at the industrial level of 1 mm. The resulting values obtained by the researchers present a turning point from which the manufacturing and sustainability in injection molding of said plastic geometries is possible, taking into account that the geometric manufacturing features 30 analyzed, will present a great demand in the coming years in the auto parts manufacturing industry