Most of the carpet you will see is "tufted," produced on tufting machines. Basically, these are huge sewing machines that insert big stitches, or loops, of pile fiber into a backing material. They often use over 1,000 needles in the process and can be adjusted to vary the height of individual loops throughout the surface of the carpet. After the loops are inserted into the "primary" backing material, carpets are dyed and a heavy layer of liquid sizing (latex) is applied to the underside to firmly lock the loops in place. Over this, a "secondary" backing material is bonded to add further strength and stability. Tufting is the fastest and most economical method of manufacturing carpet and, because of this, tufted carpet is generally less expensive than woven carpet. Tufted carpet gives serviceable quality and comes in a variety of styles. Even intricate "woven" effects are possible through tufting with today's new technological advances. Over 90% of American-made carpet is now produced by this process.
Weaving is the second most popular method of producing carpet today Basically, it consists of interlacing the filling yarns (the face or surface of the carpet) with warp yarns in a variety of techniques, each of which gives a different appearance to the carpet (i.e., Axminster, Chenille, Velvet and Wilton). This method can produce very intricate and beautiful designs.
Though not prevalent in quality residential uses, some carpeting is also produced by knitting, needlepunching or by a process which is becoming more important called "fusion-bonding." In fusion bonding yarn is embedded between two parallel sheets of adhesive-coated backing. Then the sheets are slit apart, forming pile carpet on both sides. Manufacturers can use less yarn since no fiber is hidden in the back of the carpet. And because the fiber has a higher density it performs better than tufted carpet.