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The nature of the resin flow front through the preform affects the quality of resin transfer molded (RTM) parts. The resin flow varies as the permeability of the preform. Race tracking occurs when the resin flows at a faster rate along the mold periphery than in the middle section and arrives at the vents before mold filling is complete. While race tracking is natural to the RTM process, very severe race tracking could adversely affect the filling process. A parameter has been developed to assess the skewness of the flow and is being extended to quantify the severity of this race-tracking.

A major concern in Resin Transfer Molding is race-tracking whereby the matrix flows around the preform and arrives at the vents prematurely. Race-tracking, which is usually caused by a preform-mold misfit, could cause an entire part to be scrapped since recovery from a non-fill is not possible for these thermoset composites. The mold-preform-fit is evaluated by correlating the flow characteristics of nitrogen gas introduced into the ready-to-inject mold with the nature of the skewness of the actual resin flow front. The technique enables us to evaluate the process setup and to determine whether to inject the resin or to re-work the preform-mold fit before the resin injection process.