12. Design rules for rotomolded parts

If the polymer covers the walls during the rotational movements, almost all shapes may be achieved. However, for the design of a rotomolded part, it is necessary to respect the following rules :

• the internal surface is free which may induce variations in the wall thickness of the part. This variation strongly depends on the complexity of the geometry. For a given geometry, it is necessary to optimize the temperature and the rotation velocity of the two main axes to obtain a homogeneous thickness ;

• sharp edges represent obstacles to the flow of molten polymer and powder. They must be avoided (figure  33 ) ;

• rotational molding creates some special effects (figure