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What can affect the quality of rotational molding products

By admin In Art, News Posted 2023-03-29

There are many factors affecting the quality of rotational molding products, among which the more important ones are the shape of the mold, the rotational speed of the mold, the heating temperature and time of the mold, the physical characteristics of the plastic powder and so on.

1. Mold for rotational molding products: the mold for rotational molding is a single wall closed mold, which gives the outline of the product, but the internal contour of the product can not be accurate to the details. The common carbon steel plate welding is generally selected as the mold making material of rotary plastic mold. The cost of welding die is relatively low, especially suitable for large rotary plastic products. The rotary molding process has the following basic requirements: the mold is not easy to deform and bend in the process of repeated heating and cooling. The mold should be attached with a clamping mechanism which is easy to loosen, so that the mold can be closed tightly in the heating and cooling process, and can be opened easily when the products need to be unloaded and loaded.

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2. Rotation speed: generally, two adjustable motors are used in the rotary molding machine to provide power for the rotation and swing motion of the mold around the main shaft and the secondary axis, so that the rotational speed of the mold around the main shaft and the swing around the secondary axis can be adjusted. By adjusting the speed of the two speed regulating motors, the relative uniform wall thickness of the products can be obtained in any shape of the products. The basic function of the mold rotation and swing is to make the powder materials evenly mixed and spread over the mold surface.

3. Particle size of polyethylene powder: the particle size of polyethylene powder has an important influence on its melting process. The smaller the particle size, the larger the ratio of surface area to volume, and the higher the melting rate. Generally, the particle size of rotary molding powder should not be less than 30 mesh, but the particle size should not be too small, because too fine powder is easy to absorb moisture and agglomerate, and it is difficult to dry, which increases the process difficulties. Too fine powder materials will agglomerate when rolling in the mold, resulting in uneven heating of the powder, eventually forming uneven wall thickness of the product or forming insufficient melting plastic in the product.

4. Heating time and cooling time: if the heating time is too short, the powder will not melt completely, and the plastic properties will not reach the high index. If the heating time is too long, the plastic will be oxidized, which will damage the molecular structure of the plastic, easy to aging and brittle, and affect the quality of the rotational plastic products. The cooling time is also very important. If the cooling time is too fast, it will easily deform the products and affect the usability and aesthetics of the products.

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