Continuous vulcanization is a manufacturing process in which a rubber or rubber-like material is extruded onto a wire or cable under high pressure to form a seamless, close-fitting insulation or jacket that is then cured continuously rather than in batches.
Continuous vulcanization (CV) represents a key advancement in wire and cable production, enabling faster, more consistent, and higher-quality insulation and jacketing compared to traditional vulcanizing methods. In this process, the base material, often a rubber, thermoset, or elastomeric compound, is extruded over the conductor under high pressure to create a uniform layer. The extruded coating then passes through a heated chamber, such as a steam, gas, or fluidized bed tube, where it undergoes vulcanization (or curing). This chemical process cross-links the polymer chains, giving the insulation enhanced elasticity, toughness, and resistance to heat, moisture, and chemicals.
The continuous nature of this process ensures a smooth and consistent finish, which is vital for maintaining electrical integrity and long-term performance in industrial and commercial cable applications. It also improves manufacturing efficiency, reduces material waste, and allows for precise control of wall thickness and concentricity. CV lines are typically used to produce medium- and high-voltage power cables, instrumentation cables, and specialty rubber-insulated conductors used in demanding environments.
The process and material standards related to continuous vulcanization are commonly governed by the Institute of Electrical and Electronics Engineers (IEEE), Underwriters Laboratories (UL), and the International Electrotechnical Commission (IEC). These organizations establish requirements for insulation integrity, dielectric performance, and heat resistance in vulcanized cable constructions.
The concept of vulcanization was pioneered by Charles Goodyear in the 19th century, revolutionizing the use of rubber by making it durable and stable under varying temperatures. The continuous vulcanization method emerged in the mid-20th century as wire and cable manufacturing advanced toward automated, high-speed production. This innovation allowed manufacturers to produce longer cable runs with greater uniformity and reliability, aligning with the growing demands of industrial automation and high-voltage power systems.