| Abstract: | Two engineering plastics, an acrylonitrile-butadiene-styrene resin (ABS resin, Cycolac MS) and a rigid polyvinyl chloride resin (PVC resin, Dacovin 2082) were investigated to determine the effects of cold working. In particular, the “bending under tension” stress system of a deep drawing process was considered. The object was to determine the effect of the blank-holder pressure, the ratio of the punch radius to the material thickness, the speed of deformation and the temperature of deformation. The stress-strain characteristics of the deformed and undeformed material were markedly different. Upper yield points were lower in the deformed specimens, the tensile strengths were decreased by 10 to 15% and the %-elongation at break was higher—up to double the values for underformed specimens. An analysis indicated that these effects can be attributed to non-homogeneous yielding. The results also indicated that crazing plays an important role in permitting an ABS material to permanently conform to a radius with no geometric constraints. |
