The high-quality rotomolding products need reasonable design which requires designers have profound knowledge and extensive experience.
1. Rotomolding products should have uniform thickness
Generally speaking, most rotomolding products have uniform thickness for the rotomolding technique, except for some corners. The inaccuracy of wall thickness can be controlled within ± 10%. Another feature of rotomolding products is that it’s hard to give strict control wall thickness for very single corner, therefore, it’s impossible to label specific inner dimension for rotomolding products. The ideal method is to control the thickness between normal thickness and minimum thickness.
2. The radius of corner rotomolding products
Rotomolding products should have enough corners, or it will be difficult for raw materials to flow into the mold cavity and will cause some defects. The corners have lager radius to improve the flow of material and uniformity of thickness. At the same time, it also can inhibit the forming of internal force and warpage of products, of course, the radius can not expand without limit, or it will have concave on products’ surface.
3. Design and application of reinforcement ribs
Due to the special structure of the mold, during cooling, it is easy to lead to the concave of rotomolding products. In order to avoid this problem during manufacturing, the most widely used method is the application of reinforcement ribs. In this way, it can not only prevent the concave and improve the strength of rotomolding products, but also can reduce the wall thickness and cost, and improve the performance. Therefore, the reinforcement ribs play a significant role in rotomolding products’ designing.
4. Screw thread
The internal and external screw thread of rotomolding products can be design, however, the screw thread can not be over tight, for the automatic shrinkage problem during manufacturing. Trapezoidal screw thread and sawing screw thread are widely applied, but the engagement can not be too long.
5. Inserts
Rotomolding products can apply the metal or non-metallic inserts. When choosing metal inserts, we need to focus the diathermancy of inserts, so that the products and inserts can be tightly agglutinated. All inserts should be blunt to prevent the forming of internal force. When applying metal inserts, the compatibility between material and products should be taken into serious consideration.
