overlocking

Overlocking, commonly known as serging in American usage, is a sewing technique performed by an overlock machine to finish fabric edges while sewing and trimming them in a single operation. The machine uses multiple threads and a front-facing knife to trim the edge and wrap it with a tight, durable stitch that prevents fraying. Overlock machines are designed with loopers, feed dogs, and a knife, allowing edge finishing at high speed.

Typical configurations include 3-, 4-, and 5-thread stitches. A 3-thread overlock uses two needles and one looper to create a finished edge suitable for woven fabrics. A 4-thread overlock adds a suturing chain for a wider seam and is commonly used on knits. A 5-thread setup combines a safety stitch that locks the edge and seam, providing durability and elasticity for garments. Rolled hems—narrow, lightweight finishes—can be produced with specific thread and tension settings.

Uses and applications include garment construction, home textiles, and any project requiring neat, stretchable edges. Overlocking excels at finishing edges and seams on both woven and knit fabrics, reducing fraying and bulk while enabling faster production. It is especially valued for elastic seams on stretch fabrics and for finishing raw edges on garments, activewear, and upholstery.

Operation and maintenance emphasize correct threading and tension adjustment, as incorrect setup can cause skipped stitches or broken threads. The built-in knife poses a risk of injury, so hands should stay clear during operation. Regular cleaning, blade maintenance, and proper needle and thread selection help maintain stitch quality. The term overlocking varies regionally, with serger used more commonly in some locations.