There may be a variety of reasons for air bubbles in rotomolded products, mainly including the following situations:
1.Material problem: If the material used contains a large amount of volatile substances or moisture, it is easy to produce bubbles during the heating process. Especially in the manufacture of plastic products, toxic substances in the materials may also produce harmful gases. In addition, a melting index that is too low can also lead to the formation of bubbles.
2.Temperature problem: During the manufacturing process, if the heating temperature is insufficient or the heating time is insufficient, the material may not be heated enough to fit perfectly with the mold, resulting in bubbles.
3.Pressure problem: The pressure is not enough or uneven during manufacturing, which can easily lead to the formation of bubbles. These bubbles can be caused by gas being indented into the material, or they can be caused by insufficient adhesion between the material and the mold.
4.Mold design: The design of the mold may also affect the generation of air bubbles. For example, the diameter of the mold ventilation pipe is too small or blocked, the pressure inside and outside the mold is not balanced enough, the internal pressure increases, and the resistance increases when the gas escapes, resulting in residual gas in the raw material, resulting in bubbles in the product. In addition, the mold parting surface is not tightly closed or there are sand holes and pores on the cavity surface of the mold, which may lead to air bubbles on the rotomolded product during molding.
5.The gas in the raw material: the gas in the raw material is not completely excluded, and gradually melts and flows and adheres to the mold cavity during the heating process, in this process, the gas trapped in the raw material is gradually squeezed to the surface, but due to the existence of the melt surface tension, if the gas pushes out with insufficient force, it will be unable to detach from the melt surface, and can only be nested in the raw material, thus forming bubbles on the surface of the product.
In order to reduce air bubbles in rotomolded products, corresponding measures can be taken, such as selecting the right material, controlling temperature and pressure, optimizing the mold design, etc. At the same time, for products that have bubbles, you can try to repair them, such as using hot melt adhesives, epoxy resins and other methods to remedy. However, please note that if the damage to the product is severe or the repair effect cannot be determined, it is best to consult a professional or the manufacturer's advice.