Raw materials. All vinyl products are made from combinations of vinyl resin and various additives which give these products their particular properties. For more information on the vinyl resin manufacturing process, see general vinyl section. Every formulation is different, and most are proprietary. When selecting electrical products, it is essential to choose the right combination of properties to meet the requirements of a particular building. The safety and efficiency of a building depend on an electrical system that performs consistently under a wide range of conditions. Some of the additives commonly used in flexible vinyl electrical products to give the required performance include:
•Plasticizers, which make vinyl flexible even at low temperatures and also give excellent mechanical properties, impact resistance and abrasion resistance.
•Stabilizers, which are an essential ingredient in all vinyl formulations to prevent decomposition during processing. They can also enhance vinyl's resistance to daylight, weathering and heat aging, and have an important influence on the physical properties of the vinyl formulation. The choice of stabilizer will depend upon the end-use application, other factors including the technical requirements of the vinyl product, regulatory approval requirements and cost.
•Fillers. These are primarily used in vinyl electrical compounds to reduce formulation costs and improve insulation resistance, but they also provide smooth matte surface finishes.
•Fire retardants and smoke suppressants. Although vinyl's raw materials provide inherent fire resistance, fire retardants and smoke suppressants may also be used in specialized formulations. These additives have the effect of slowing the spread of an accidental fire and reducing the amount of heat and smoke released, which gives occupants of a building more time to escape.
•Lubricants. To improve the ease of processing, wire and cable manufacturers may add lubricants such as stearic acid to the vinyl compound. Lubricants help provide a consistent, flawless surface finish and make it possible to produce long lengths of wire at high line speeds.
•Pigments. Vinyl wire and cable compound can be manufactured in virtually any color, which is crucial for identification purposes. In some cases, pigments used can have an impact on the end-use product's performance and are chosen very carefully.
Processing/fabricating. Once the additives have been combined with the resin, the resulting material is called vinyl compound, and is often in pellet form. To manufacture vinyl-jacketed wires and cables, these pellets are melted down and extruded over the conductor wire or insulated cable. Once the jacketing has been applied, the cable is cooled in water and wound onto reels to ship to a job site or retailer.
In the case of rigid vinyl electrical products such as raceways and electrical switch boxes, the manufacturing process is similar although different additives are used. Rigid applications do not require the use of plasticizers, and a different mix of modifiers is used to impart the desired characteristics for these products. Raceways are extruded in long hollow tubes (like pipe) and switch boxes are injection molded by forcing melted vinyl compound into a shaped mold and allowing it to cool. Raceways are sold to contractors or retailers in diameters ranging from 1/2" to 6", and typically in 10' lengths. Some products are available in long-length coils.