A Brief Discussion On How Rotational Molding Molds Are Not Prone To Deformation And Deflection
Molds for roto-molded products The molds used for roto-molding are single-wall closed molds, which give the outer contour of the product but cannot accurately determine the internal contour of the product. The mold material for roto-molding molds is generally selected from ordinary carbon steel plates for welding. The cost of welding molds is relatively low, especially suitable for large roto-molded products. The roto-molding process has the following basic requirements for its molds: the mold is not easy to deform and bend during repeated heating and cooling.
The mold should be equipped with a clamping mechanism that is easy to loosen so that the mold can be tightly closed during the heating and cooling process, and can be easily opened when the product needs to be unloaded and loaded. The design and installation of the roto-molding mold should be conducive to the relative movement of the airflow around the mold surface so that the mold can be evenly heated and cooled.
The roto-molding mold should be equipped with a ventilation duct to prevent the gas in the mold from expanding due to heat during the heating process and squeezing out the molten plastic along the mold seam, and to prevent the negative pressure in the mold from causing deformation of the mold and the product during the cooling process.
When designing the local structure of the mold, try to avoid deep cavities and holes, as well as structures such as reinforcing ribs and solid protrusions, because it is difficult for powdered materials to cover the surface of the above structures.
In most roto-molding processes, plastic molds are under quite high pressure (pressure) during the molding process, such as widely used injection molding, compression molding, extrusion, blow molding, etc. Therefore, when these molding processes are used to produce large plastic parts, not only must molds that can withstand great pressure be used, making the molds bulky and complicated, but the plastic molding equipment must also be designed and manufactured very firmly, and the difficulty of machine mold processing and manufacturing increases accordingly, and the cost increases. On the contrary, since the roto-molding process only requires the strength of the frame to be sufficient to support the weight of the material, mold and frame itself, as well as the closing force to prevent material leakage, even if large and extra-large plastic parts are roto-molded, there is no need to use very bulky equipment and molds. The processing and manufacturing of machine molds is very convenient, with a short manufacturing cycle and low cost. In theory, there is almost no upper limit on the size of parts formed by roto-molding. It is impossible to produce such a large plastic container by blow molding without very expensive and large blow molding equipment.