molding

Molding is a manufacturing process in which a material is shaped by confining it within a mold that has a hollow cavity in the shape of the desired part. The mold is typically a rigid tool, though flexible molds are used for certain applications, and it is usually made of metal or durable polymers. Molding is widely applied to plastics, metals, ceramics, and composites. The forming occurs as the material flows, fills the cavity, and cures or cools to achieve the final part.

Common molding processes include injection molding, where molten plastic is injected at high pressure into a cooled mold; blow molding, which forms hollow parts by inflating a preformed tube; compression molding for thermosetting plastics and rubbers using heated platens; rotational molding to build hollow, seamless parts by coating the interior while the mold is rotated; and thermoforming, where a heated sheet is formed over a mold and held by vacuum or pressure. For metals, processes such as die casting and investment casting use molds or patterned cores to shape molten alloy into desired forms.

Mold design and fabrication are central to molding quality and efficiency. A mold typically comprises cavities, cores, gates, runners, and cooling channels, with tolerances, surface finishes, and draft angles affecting part quality. Materials range from hardened steel for high-volume production to aluminum for rapid prototyping. Molding requires consideration of cycle time, material behavior, part ejection, and post-processing. Proper maintenance and inspection extend mold life and reduce defects.