Types Of Sewing Machines
Sewing machines are designed to create one of two basic types of stitches. The chainstitch is created as a single thread loops through itself on the underside or edge of the fabric, and is used for such purposes as button holes and edgings. The lock stitch is created as two separate threads—one below the fabric in a bobbin, the other above on a spool, lock together from the top and the bottom of the fabric at each stitch. The lock stitch is used most widely in both industrial and home sewing, and is stronger than the chain stitch, but because it puts more tension on the thread, cannot be created as quickly. (Industrial lockstitch machines can sew up to 6,000 stitches per minute, while the fastest chainstitch machines can sew 10,000 stitches per minute.) In the early 1970s, manufacturers of industrial machines began to incorporate computerized technology into their products. Because these machines could be programmed to perform a number of the steps previously done by the operator, the new technology halved the number of steps (from 16-8) in a labor-intensive task such as stitching together the various parts of a collar (top ply [outer collar], inter-lining, lower ply, two-piece collarband, and collarband interlining).
Innovations in the 1970s led to the design of three types of machines. Dedicated machines incorporate microprocessors capable of controlling the assembly of apparel parts such as collars, and the operator simply loads the pre-cut clothing parts into these machines. Programmable convertible machines can be converted to perform a number of different tasks, and in this case, too, the operator just loads the pre-cut fabrics. Operator-programmable machines can be taught new sewing procedures as the operator performs the task with the machine in "teach" mode, and the machine "learns" the various parts of a task. The machine can then perform most of the functions except placing the material.