Interlock Sewing Machine (Coverstitch Machine)
Industrial interlock sewing machine, also known as coverstitch machine, is a specialized industrial sewing equipment designed for stretch fabrics and knitwear production. It can form beautiful, elastic interlock cover stitches, widely adopted in garment factories, underwear workshops, sportswear production lines and apparel finishing workshops.
Different from lockstitch machines which make non-elastic seams, the interlock machine produces multi-thread chain cover stitches. The seam can stretch together with fabrics without breaking, which is the core advantage for knitted garments. It commonly comes in 2-needle 4-thread or 3-needle 5-thread configurations. The top side shows neat parallel decorative cover stitches, while the underside forms flexible chain loops, delivering both aesthetic appearance and strong seam durability.
This machine is available in flat bed and cylinder bed versions to satisfy different production requirements. Flat-bed models are suitable for flat fabric hemming, shoulder seam joining and waistband attachment. Cylinder bed (small square head) interlock machines feature a narrow cylindrical arm, making it easy to handle tubular workpieces such as trouser legs, sleeves, underwear cups and pant legs. Operators can slide cylindrical fabric onto the cylinder bed smoothly without fabric twisting or shifting during continuous sewing.
The feeding system adopts optimized differential feed mechanism. It can adjust the feeding ratio to prevent fabric stretching, shrinking and puckering, especially for thin, slippery and highly elastic materials like jersey, spandex, rayon and lycra. The active thread tension control system stabilizes thread tension all through the sewing process, effectively reducing thread breakage, skipped stitches and uneven stitch density. It can maintain consistent stitch quality at high running speed.
Equipped with direct drive servo motor as standard optional upgrade, the machine runs with low vibration and low noise. It saves power compared with traditional clutch motors and responds instantly at start and stop. Optional automatic functions include automatic thread trimmer, automatic presser foot lifter and needle position stop. After finishing each sewing section, the auto trimmer cuts both needle thread and looper thread cleanly, eliminating manual thread cutting and greatly improving working efficiency for mass production. The oil-proof and anti-leakage structure prevents oil stains on garments, which is critical for light-color knit products.
This interlock machine handles multiple sewing processes: bottom hemming of T-shirts, sweatshirts and dresses, collar binding, elastic band attaching for underwear and swimwear, waistband sewing, cuffs finishing, decorative topstitching and seam reinforcement. It works well for light, medium and slightly thick materials: jersey, spandex, cotton knits, modal, polyester knit and blended stretch fabrics.
Simple daily maintenance keeps stable long-term performance. Users should regularly clean lint and thread waste from looper, feed dogs and needle area, and add sewing oil according to the maintenance schedule to reduce wear of moving parts. Whether you run a small knitwear workshop or large-scale garment manufacturing enterprise, this industrial interlock sewing machine provides reliable elastic seams, improves finished garment quality and increases production throughput for your apparel business.