Moldability diagrams for the reaction injection molding of a polyurethane crosslinking system

A trial and error approach reflects the state of the art in reaction injection molding. Material and process parameters determine the “moldability” of a specific system in a particular application. The concept of “molding areas” on the critical parameters plane can be extended form thermoplastic injection molding (TIM) to reaction injection molding (RIM). In this work moldability diagrams for the filling and curing stages of a RIM process are obtained based on a simplified engineering approach. The key process parameters chosen for the filling stage are initial material temperature and filling time. In the curing stage, the critical parameters are considered to be mold wall temperature and demold time. Experimental results obtained on a laboratory‐scale RIM machine on a Crosslinking polyurethane system are used to check the validity of the predicted molding areas. The agreement obtained is satisfactory considering the broad range of processing parameters used.