What distinguishes blow moulding from other moulding processes?

Blow moulding is distinctly characterized by its use of gases to form the shape of hollow objects. This process involves the introduction of air or gas into a heated plastic tube (parison) that is situated within a mould. As the gas expands, it pushes the molten material against the walls of the mould, shaping it into the desired form. This method is particularly effective for producing hollow items such as bottles and containers.

In contrast, the other options describe characteristics of different processes or would not accurately depict blow moulding. For instance, blow moulding does not form materials without heat, nor does it typically utilize a two-part mould in the same way that other methods, like injection moulding, do. Additionally, while injection moulding involves the injection of molten material, blow moulding specifically requires gas for shaping, setting it apart from these other techniques.