Knitting Machinery
KNITTING MACHINERY
Knitting machinery is the primary means of producing fabrics by the knitting process outside of the crafts businesses. Mechanical production of knitted fabrics began in England in the sixteenth century with the invention of the circular knitting machine by William Lee. In the 1700s knitting machines were attached to power drives moved by water or wind for the first time and the individual production of knits as a cottage industry began to decline.
The function of an automatic knitting machine is dependent on the design and function of the knitting needles the machine uses. The knitted stitches in the fabric body are identified by component rows of needles. The stitches formed along the yarn feed direction are courses. Those formed along the position of each individual needle are the wales. There are three major categories of knitting needles for automatic machines: spring beard, latch hook, and compound (or bipartite). Each of the needle types is designed so that when it is extended, it contacts a yarn on the lower, or shank, end of the needle. It is retracted to capture the yarn inside a hollow head formed by an outer hook, and forces a previously formed loop of yarn over the outer hook to hold and form a loop with the internally held yarn inside the hook head. As the needle is extended, the internal yarn slides out of the hook interior and the head of the newly formed loop relaxes so that it cannot return into the hook interior, but rather must slide along the shank and over the hook head to capture and form the next loop of yarn in the needle. With the spring beard and latch hook needles all of the actions are entirely passive and require no external activation. The compound needle is machine activated.
Machine knitted fabric types fall into two broad categories: weft knits and warp knits. Weft knits are characterized by the use of one set of feed yarns that form loops on each successive row of previously formed loops in rows that are known as "courses." They may be produced in either circular or flat form, but require no manipulation of the weft yarns other than by the knitting needles themselves.
Warp knits are fed from warp beams very similar to those mounted on looms, but they do not require the interlacing of weft yarns for fabric formation. Like weft knits, they form interloopings of yarns in courses. Unlike weft knits, they do not interloop individually with themselves but rather require outside manipulation of their paths over or under neighboring knitting needles. Manipulation of the warp knit yarns is effected by means of needle guide bars that hold eyelet guides used for the major motions of warp knitting—the swing (front to back) and the shog (left to right). The swing and shog motions combine to produce bindings among weft knit yarns in both the wale and course directions and may be altered to produce open, long shogs, tighter, short shogs, reverse side underlaps or looser overlap loops in the structures. These knits may have inlays of yarns that are orthogonal to the warp yarns that are known as weft yarns, but they do not act like the weft yarns in a woven fabric because they are not required for the structure to hold together.
bibliography
Brackenbury, T. Knitted Clothing Technology. Cambridge, Mass.: Blackwell Scientific, 1992.
Collier, B., and P. Tortora. Understanding Textiles. Upper Saddle River, N.J.: Prentice-Hall Inc., 2001.
Schwartz, P., T. Rhodes, and M. Mohamed. Fabric Forming Systems. Park Ridge, N.J.: Noyes Publications, 1982.
Spencer, D. J. Knitting Technology. Oxford: Pergamon, 1989.
Howard Thomas