Exploring the intricacies of rotational moulding, also known as rotational or rotary casting, reveals a fascinating process. As described in the article “Rotational Moulding (Rotational or Rotary Casting)” from OpenLearn, this technique involves low-pressure, high-temperature molding of hollow plastic components using three separately rotating arms.
In this process, the arms, each with connected molds, rotate bi-directionally around their axes. One arm facilitates loading and unloading of molds, another rotates within an oven, while the third holds a cooling chamber. The sequence involves adding plastisol or powder to the mold, distributing it evenly, heating while rotating, and finally opening the mold to remove the product.
Manufacture of molds varies, including steel, aluminum, Cu-Be, and electroformed nickel molds, each offering specific advantages. Molds are heated using methods like hot air, direct flame, molten salts, or circulating hot oil, with temperatures ranging from 200 to 400°C. Biaxial rotation or “rock and roll” is employed, with rotation speed ratios adjusted as per production requirements.
Rotational moulding, suitable for small to medium production runs and prototypes, demands expertise in mold design, material selection, and process control. Source:
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