Technology
PROPERTY| ROTATIONAL MOULDING
Rotational molding is an atmospheric pressure process that produces nearly stress-free parts. The fact that there are no stresses on the melt as it is shaped is a major advantage that rotational molding has over all other manufacturing methods for plastics parts. Also, as there are no forces on the plastic melt during forming, rotational molds can have thin walls and are relatively inexpensive to fabricate. For simple parts, mold delivery times can be a few days or weeks. Modern, multi-armed machines allow multiple molds of different sizes and shapes to be run at the same time. With proper mold design, complex parts, such as double-walled containers, that are difficult or impossible to mold by any other method, can be rotationally molded. With correct process control, the wall thickness of rotationally molded parts is quite uniform, unlike structural blow molding or twin-sheet thermoforming.
FLATNESS
Wide flat surfaces are usually difficult to produce in all plastic moulding processes. In rotational moulding the difficulty is higher because the polymer is only bonded on the external part (to the mould). Therefore, it is usual experience that in flat zones warpage often takes place: a wide concave or convex deformation of the part walls.