September 30, 2023

Basics of rotational molding

Rotational molding is the engineering casting process that will provide hollow plastic components that are made of polymer resins such as polyolefins or polyethylene. You can witness four processes during the production of a component. The powder is put into the rotating mold, and heating is done. The polymer will melt in the heat and coat along the walls of the mold. Hence, your component will be ready after cooling. Custom rotational molding is the process of producing products that are customized for your client’s requirements. In this article, let us discuss the difficulties that you will face during the processes in brief. 

Difficulties in the rotational molding process 

Inability to produce flat surfaces

The rotational process of molding is a brilliant method to produce various products of complicated shapes. But you cannot make a simple shape using the process. It is a large flat surface on your product. You cannot make a flat surface at ease since the product is based on the rotation of the mold as a whole and the process of coating over the walls of the mold. There should at least be any deviations like a bump or a logo, so that the flatness will vary a bit. You should consider removing the flat surfaces in the design stage itself. If your clients are clear in the requirement of a lengthier flat surface, then it is advisable to consider going for any other method of production. Normally, quality engineers will avoid or modify the occurrences of flat surfaces during the design.

Sharp edges and corners 

As the difficulty of producing flat surfaces, it is tedious to make out sharp edges and corners using rotational molding. The nature of the process of rotation can be a reason for this inability. Although you can modify your mold to make a sharp edge, you will face some more difficulties in your product. If a sharp edge is there in your mold, it will be like a cavity with a narrow edge blocking the further flow of material. So, the liquid polymer will not find a way to move freely inside that portion of the mold. It will affect other parts of the product, and there are chances for the creation of gaps or voids in the final component. So, you should better consider removing these sharp edges or replacing them with a slightly bent edge in the design stages itself. 

Walls in the product

Not every product you work on in rotational molding will be round or hollow throughout. Some products may include some walls, ribs, or other blocking structures. In these cases, you should restrict the material flow in the gap between the two structures of the product. Since the material will be in liquid form, it will flow through the gap and fill it. So, your final product will not be as expected. So, it is better to design the product with at least five millimeters between these structures.