If you have already reviewed the solution dyeing section, the fiber extrusion process already has been briefly described. All synthetic fibers begin as pellets and they are then melted into hair-like filaments. These filaments are extruded in infinite lengths and the number and diameter of filaments determine the final size of the yarn ply that will be used for the finished carpet product. These filaments may be left as infinite lengths to form bulked continuous filament (BCF) fiber or may be chopped into short lengths for further processing (See staple fiber).
The extrusion of fiber into continuous filaments, limits the carpet manufacturer in styling flexibility. If the spinneret has 1400 holes, the yarn ply must have 1400 filaments throughout the manufacturing process. The size (diameter) of the yarn-ply must remain constant throughout the manufacturing process and cannot be altered. Two of these yarn plies of filament are combined to form the finished fiber that is tufted into carpet.
Staple fiber is obtained by chopping BCF fiber into short lengths. This gives the manufacturer styling flexibility by allowing various ply sizes. These chopped fibers are blended and spun to form long plies of yarn.
After extrusion and spinning (in the case of staple fiber), the individual plies must be combined to prepare for tufting. Twisting is a process of applying twist to the two ply's to bind them together. The amount of twist greatly impacts the cost and finished performance of the finished product (See Twist Level). There are various types of twist such as "S" twist and "Z" twist, but for the consumer it is only important that you understand that there are usually two plies of yarn in most finished carpet products, and the level of twist can affect price and performance.
Following twisting, the yarn must be heat set to lock in the yarn memory and prevent the yarn from unraveling. Heat setting is a process of applying dry heat or steam to the plied yarns. This is an especially important step for cut pile fabrics, which require the fiber twist to hold their aesthetic appeal. There are various types of heat setting, but their explanation would probably be confusing and not relevant for most consumers.
Some fibers, especially olefin, are air entangled rather than twisted and heat set. Since olefin does not have good yarn memory, this process is sufficient for olefin used in loop pile constructions. Air entangling is a process of using forced air to wrap the two plies of yarn together in a loose marriage. This process usually gives the bulky appearance found in many Berber constructions.
Carpet fiber processing affects carpet performance based on yarn denier size, carpet fiber processing technique, and twist level. The type of yarn processing performed actually influences a number of carpet performance factors, such as matting and crushing, carpet stains, and even carpet price.
About the Author
Michael Hilton was the original creator of Carpet Buyers Handbook. Having owned and operated a carpet wholesale company, Hilton has a vast knowledge about all-things carpet related as well as other types of flooring.