Materials Used in Rotational Molding: Types and Properties

The rotational speed of the mold is not high in rotomolding processing, and the molding of the products all depends on the natural flow of resin, so the products are almost free of internal stress, and are not easy to be deformed, dented, and other shortcomings. However, not all materials can be processed by this method. This article will introduce some rotational molding material.

Working Principle

Rotational molding is a thermoplastic hollow molding processing method. The resin is added to the mold, the mold is closed, the mold is heated, and at the same time, the mold is rotated uninterruptedly by two right-angled intersecting shafts, so that the mold rolls in three dimensions. The resin evenly spreads all over the inner cavity of the mold with the help of its own gravity and melts gradually until the resin is completely melted and uniformly adheres to the inner wall of the mold cavity. Then the heating is stopped, and the cooling process is transferred to the cooling process, and the desired seamless hollow products are obtained by removing the mold after the products are cooled and solidified.

Polyethylene Resin

Dry powder rotational molding represented by polyethylene resin is the most widely used rotational molding material, as the resin is forced to extrude from powder to melt without external force, the air bubbles formed in the melt between the original powder particles can only rely on their own aggregation to grow up, and then exclude from the melt. Whether the air bubbles can be completely exhausted directly affects the physical and mechanical properties of the product.

Polypropylene

Polypropylene is a lightweight rotational molding material, with a small relative density and excellent mechanical properties. PP's heat resistance is high, continuous use of temperature up to 110-120 ℃, so it is suitable for the manufacture of plastic products need to withstand high temperatures. In addition, PP has good chemical properties, almost non-absorbent, and the vast majority of chemicals do not react, to ensure the stability of the products. The transparency of polypropylene products is also better, suitable for the manufacture of products that require transparency.

Nylon

Nylon is a high-performance rotational molding material with high tensile and compressive strength, superior to ordinary plastics. Nylon's fatigue resistance is excellent, parts can maintain the original mechanical strength after repeated bending. In addition, nylon also has good heat resistance and wear resistance, can be used for a long time in high temperature and friction environments. Nylon has a smooth surface, low coefficient of friction, self-lubricating, and low noise characteristics, suitable for the manufacture of movable mechanical parts.

In short, rotational molding is a kind of wide applicability with wide applicability. It can mold seamless hollow products as small as ping-pong balls, as large as yachts, or chemical storage tanks with hundreds of cubic volume. Choosing the right rotational molding material can give full play to the advantages of rotational molding technology, and produce plastic products with excellent performance and reliable quality.