Perceptions of Prepreg Tack for Manufacturability in Relation to Experimental Measures

A full factorial design of experiments was performed on prepreg tack by varying the processing conditions of BMS 8-212 3K-70-PW, an epoxy based carbon fiber reinforced fabric prepreg, processed in a solution dip prepregging process. The processing conditions varied were line speed, tower temperature, and resin content. Tack measurements were performed both qualitatively on the Boeing shop floor by lay-up personnel, and quantitatively using a compression to tension test previously developed by Seferis and Meissonier III. Relationships were then developed between quantitative and qualitative tack which help define optimum processing conditions for processing the prepreg. Furthermore, the prepreg characteristics of resin content and volatiles content were evaluated, as well as prepreg quality through optical photo-micrographs. From this design of experiments, the operating conditions as well as volatiles content were optimized for "ideal" tack materials and this "ideal" tack could be 'Author to whom correspondence should be addressed measured quantitatively corresponding to perceptions provided by users on the manufacturing floor. Ultimately, from, this "ideal" tack a quantitative processing window was established that could eliminate the extremes of tack (i.e., too dry, too sticky). The importance of this result is also that for the first time a material characterization test of tack has been analyzed and modified in relation to human perceptions.