Overlock Stitch

Overlock stitch (also called serger stitch) is produced by an overlocker or serger machine — a specialized industrial sewing machine that simultaneously performs three operations: trims excess fabric from the seam allowance, encloses the raw fabric edge in loops of thread, and stitches the seam. The result is a clean, stretch-resistant seam finish that prevents fraying.

Unlike a conventional sewing machine that uses a single needle and bobbin, an overlocker uses 3, 4, or 5 threads from spools (called a 3-thread, 4-thread, or 5-thread overlock), passing through loopers above and below the fabric to create the characteristic wrapped-edge appearance.

Common overlock configurations:

3-thread overlock:

• Used for finishing single raw edges (not joining two layers)
• Wraps the edge in a loose, stretchy loop; ideal for knit hems and single-layer edge finishing
• Very efficient; fastest overlock operation

4-thread overlock (safety stitch):

• Combines a chain stitch (for seam strength) with an overlock edge finish
• Most common in garment production for joining and finishing seams simultaneously
• Strong and flexible; used extensively in t-shirts, casualwear, and knit garments

5-thread overlock:

• Combines two-needle chain stitch with three-thread overlock
• Maximum seam strength; used in demanding applications (activewear, jeans outseams, workwear)

Flatlocking:

• A specialty overlock technique where the seam is opened flat after sewing, creating a decorative visible seam on the right side
• Used in activewear, athleisure, and technical garments; also decorative in womenswear

Mock flatlocking / cover stitch:

• Technically a separate machine operation but related; used for hems in knit garments to create the clean, two-row top-stitch visible on T-shirt necklines and sleeve hems

Overlock machine sourcing in India (for brands with in-house production or sampling units):

• Juki India (industrial): Distributed through authorized dealers in Bangalore, Delhi, and Mumbai. Industrial 5-thread overlocker: ₹45,000–₹1,20,000 ($540–$1,440)
• Brother (industrial): Available through India distributors; industrial overlocker range ₹35,000–₹85,000 ($420–$1,020)
• Pegasus: Japanese brand widely used in Indian export factories; available through Mumbai and Delhi dealers
• Usha and Singer (domestic semi-industrial): More affordable entry-level overlockers for sampling rooms or small production; ₹15,000–₹35,000 ($180–$420)

Thread for overlocking:

• Overlock thread is typically 120/2 or 150/2 weight polyester or cotton-core poly (corespun)
• Available in wholesale quantity (5,000–10,000 meter cones) from thread suppliers
• Coats India, Madura Coats: Major thread brands available nationally
• Wholesale price: ₹40–₹90 ($0.48–$1.08) per 5,000-meter cone

Maintenance note: Overlock machines require frequent cleaning (lint removal), oiling, and blade replacement for consistent quality. When auditing a factory, ask to see their machine maintenance schedule.

Overlock stitch cost context:

Overlock stitching is one component of CMT (Cut, Make, Trim) pricing — it is not typically broken out as a separate line item except in detailed cost analysis.

Machine costs:

• Industrial overlocker (Juki, Pegasus, Brother): ₹35,000–₹1,20,000 ($420–$1,440) new
• Second-hand industrial overlocker: ₹12,000–₹45,000 ($145–$540)
• Maintenance: ₹2,000–₹6,000 ($24–$72) per service; recommended every 3–6 months in high-volume production

Thread cost per garment:

• A basic T-shirt uses approximately 80–120 meters of overlock thread across all seams
• At ₹0.008 per meter: approximately ₹0.64–₹0.96 per T-shirt in thread cost
• Thread is a very low direct cost but quality thread (Coats, Madura) vs. cheap thread significantly affects seam consistency and appearance

Labor cost context:

• Overlock machine operator (industrial, India): ₹12,000–₹20,000/month ($145–$240) in Tier 1 cities
• Per-piece overlock operation: approximately ₹2–₹8 per seam operation depending on garment complexity and region
• In a full garment CMT quote, seaming/overlocking typically represents 35–55% of the total making cost