Sewing machines can be classified in many ways, but the most common is by stitch type and application. Sewing machine stitches can be broadly categorized into lockstitch and chain stitch. Lockstitch is the most common; it consists of two threads interlaced like a rope, with the interlacing point in the middle of the fabric. Viewed in cross-section, the two threads resemble two locks locked together, hence the name lockstitch. This stitch is used on fabrics with low shrinkage, such as cotton, wool, or leather. The shape is identical on both sides, resembling a dotted line. The stitch is dense, and the sewing strength generally exceeds that of hand sewing.
Chain stitch is formed by self-linking or interconnecting loops of thread. Common types include single-thread chain stitch, double-thread chain stitch, and three-thread overlock stitch. This stitch is characterized by its elasticity, allowing it to stretch and contract with the fabric without breaking. It is suitable for garments made of elastic fabrics or for overlocking easily loose items and garment blanks.
In addition, sewing machines can be classified according to their use into household, industrial, and service industry machines, and according to their drive type into hand-cranked sewing machines, foot-operated sewing machines, and electric sewing machines.
