Roll forming, also known as rotational molding, rotational molding, rotational molding, rotational casting, rotational molding, etc. The rotational molding process involves first adding plastic raw materials to a mold, then the mold continuously rotates along two vertical axes and heats it up. Under the action of gravity and heat, the plastic raw materials inside the mold are gradually evenly coated, melted and adhered to the entire surface of the mold cavity, forming into the desired shape, and then cooled, shaped, and demolded to obtain the product.

The processing process of rotational molding technology

Roll forming process usually consists of several basic processes such as feeding, heating, cooling, demolding, and post-treatment.

During the heating process, the mold is heated while rotating around two perpendicular axes, transferring heat to the materials inside the mold. During the flipping process, the materials inside the mold are subject to friction between each other and drag on the inner surface of the mold, causing the materials in the material pool to move above the mold wall. Only when this force is insufficient to overcome the gravity acting on the materials, do the materials cross the top of the material pool and reach the opposite mold wall. During the rotation of the mold, the material does not rotate 360 degrees along with the mold. The dynamic angle of rest is usually used to characterize the position of material powder falling, which is related to the mold speed, material shape, and viscosity, and should generally be controlled between 25-50 degrees. Materials are mixed and heat exchanged in the mold through the following forms: one is that the materials periodically move from one position on the inner surface of the mold to another; Another type is the shearing motion of materials. As the temperature of the mold rises, the material near the inner surface of the mold is first melted and gradually forms a thin molten layer on the mold wall. Heat continues to be transferred to the center through the molten layer, so the material continuously adheres to the mold wall layer by layer, and all the material melts and adheres to the mold wall, forming a smooth surface. When the mold is heated and enters the cooling stage, the melt inside the mold begins to solidify and form into the desired shape. The post-processing process may include cutting, drilling, trimming, shaping, assembly, etc. After cleaning and applying release agent, the mold is loaded into the next cycle.

Let's summarize the characteristics of the rotational molding process:

The rotational molding process uses powdered or liquid raw materials instead of granular materials commonly used in the plastic industry; During the forming process of raw materials in molds, they are only affected by gravity without the need for additional external forces, so the products produced theoretically have no internal stress, making them more suitable for long-term use; The force on the rotational molding mold is relatively small, so the requirements for the mold material will be relatively low;

The mold can be composed of two or more pieces, and there are no restrictions on shape and size; During the processing, the mold will rotate continuously along the two vertical axes. Based on the above characteristics of the rotational molding process, we can find that its advantages include: low mold cost and short development time; For systems composed of multiple components, the use of roll forming technology can reduce time and processes; The rotational molding process is not limited by size; Can be applied to hollow open or closed products; It can produce multi-layer products (of the same or different materials) and can easily produce products with decorative patterns and other accessories; Can easily set embedded components; The finished product does not have stress concentration areas such as welds; Will not produce during production