Discussion on Rolling Forming Technology by Rolling Equipment Manufacturers
Rotational molding, also known as rotational molding, rotational molding, or rotational molding, is a hollow forming method for thermoplastic materials. This method involves first adding plastic raw materials to the mold, then continuously rotating the mold along two vertical axes and heating it. 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 the desired shape, and then cooled and shaped to form the product. Let's take a look together
1、 The main advantages of rotational molding process
(1) Suitable for molding large and oversized parts, most plastic molding processes, such as injection molding, compression molding, extrusion, blow molding, etc., are widely used. During the molding process, both plastic and molds are under relatively high pressure (pressure). Therefore, when using these molding processes to produce large plastic parts, it is not only necessary to use molds that can withstand high pressure, making the molds bulky and complex, Moreover, plastic molding equipment must also be designed and manufactured very firmly, making the machining and manufacturing of machine molds more difficult and costly.
On the contrary, due to the fact that the rotational molding process only requires the strength of the frame to support the weight of the material, mold, and frame itself, as well as the clamping force to prevent material leakage, even large and extra large plastic parts do not require the use of very bulky equipment and molds. The machining and manufacturing of the machine mold 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 the rotational molding process. We used the rotational molding process to prepare polyethylene cylindrical rotational containers with a diameter of. 2m and a height of. 2m. The molds were only made of 3mm thick thin steel plates through cold work welding, while the rotational molding frame was welded with No. 8 channel steel. It was impossible to produce such a large plastic container without using expensive and bulky blowing molding equipment.
(2) Suitable for the production of multiple varieties and small batches of plastic products. Due to the fact that the mold used for rotational molding is not subjected to external forces, the mold is simple, inexpensive, and easy to manufacture, making it very convenient to exchange products; In addition, the rotational molding equipment also has great maneuverability. A rotational molding machine can install one large mold or arrange multiple small molds;
It can not only mold parts of different sizes at the same time, but also products of extremely different sizes and shapes. As long as the raw materials used for the rotational molding products are the same and the thickness of the products is the same, they can be formed simultaneously. Therefore, the rotational molding process has greater flexibility compared to other molding methods.
(3) Rotational molding is very easy to change the color of the product. Each time the material is directly added to the mold, all of it enters the product. After the product is removed from the mold, the necessary materials for the next molding are added. Therefore, when we need to change the color of the product, we do not waste any raw materials or spend time cleaning the machine and mold. When we use multiple molds to roll shape the same plastic product, we can also add different colored materials to different molds and roll shape different colored plastic products.
(4) It is suitable for forming hollow parts with various complex shapes. During the roll forming process, the materials are gradually coated and deposited on the inner surface of the mold. The products have strong replication ability for Fine structure such as patterns on the mold cavity; At the same time, because the mold is not subject to external pressure in the molding process, it can be directly made with precision casting and other methods to produce molds with Fine structure and complex shapes, such as toys, animal molds, etc.
(5) The wall thickness of the roll molded product is relatively uniform and the chamfer is slightly thicker, which can fully utilize the efficiency of the material and is beneficial for saving raw materials; In addition, during the rotational molding process, there are no waste materials such as runners and gates. Once debugged, there is almost no return material during the production process, so the utilization rate of materials in this process is extremely high.
(6) Convenient for the production of multi-layer plastic products, using the rotational molding process, only reasonably matched materials with different melting temperatures need to be loaded into the mold for rotational molding. The plastic with lower melting temperatures is first heated and melted, adhered to the mold, forming the outer layer of the product. Then, the material with higher melting temperatures is melted onto it to form the inner layer of the product.
Alternatively, the outer layer of plastic can be first placed in a mold and rolled to form the outer layer, followed by the addition of the inner layer material, which can then be rolled to produce a multi-layer roll molded product. Regardless of the method, it can be achieved without the need for complex equipment. If blow molding or injection molding methods are used for multi-layer plastic products, special multi-layer molding machine levels and complex molds are required.
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