A new procedure for calculating cycle time in injection molding based on plastic part geometry recognition

The paper presents a new procedure for the automated calculation of cycle time in the injection molding process based on the recognition of the geometry of the plastic part to be manufactured, taking as input data only the geometry of the plastic part in discrete format and the material in which it will be manufactured. In a first phase, the procedure uses a new geometric algorithm of topology recognition of the plastic part based on the projection of a nodal quadrature on the discrete model of the part. The algorithm is able to obtain the set of geometric parameters necessary for the calculation of the cycle time by providing a map of the thicknesses of the part, indicating its average and maximum thickness as well as the maximum distance that the melt plastic flow runs during the injection stage. Afterwards, a second analytical-empirical algorithm performs an automated analysis of the numerical simulations of the injection stage using a rectangular plate shape test part whose geometry is parameterized according to its volume, its thickness, and the path of the melt plastic flow, generating a set of polynomial functions which determine the radius of the feeding system gate. Finally, taking as data, the geometric and technological parameters resulting from the application of the developed sub-algorithms, the cycle time is calculated. The new procedure presented in the paper does not require the use of additional simulation software or the empirical evaluation of experts. It is not linked to the modeler of the given part since it analyzes its surface externally from its discrete format. In this way, it allows designers to give a response to the client quickly and accurately, obtaining the value of the cycle time in a minimum time.