Experimental investigation of the warpages in rotationally molded parts

Rotational molding is one of the most important methods to produce hollow plastic articles. However there are still some unsolved problems that confound the overall success of this technique. Part warpage caused by inappropriate mold design and processing conditions is one of them. This research tends to examine the effect of different processing factors on the warpages of rotationally molded parts. The factors that were studied included part thickness, oven temperature, cooling condition, mold material, mold release agent and size of venting. A structure buckling model was also proposed to simulate the measured warpages. It is shown that the mechanisms of warpage formation and removal can be explained and having done this, steps can be taken to ensure that once formed, the warpages will be minimized. This provides significant advantages in terms of reduced cycle time and improved product quality.