The effects of material properties in the simultaneous twin-sheet thermoforming of dissimilar materials were evaluated using a selection of 1 mm thick sheets and a test mold. Forming of dissimilar sheets required major modifications to parameters recommended for similar sheets. For this system, increasing the sheet temperature provided the greatest improvement in seal strength. Mold temperature had little effect of seal strength whereas air temperature and pressure had no processing window. The seal strength was sensitive to the solubility parameter mismatch and difference between sheet temperature and critical transition temperature. When the former was large and latter was small, seal strength was inadequate. Of the materials used in this study, polycarbonate and ABS exhibited the highest seal strengths.
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