Last Updated: Nov 02, 2025 Author: Yunenx Product Development
Sportswear & Swimwear Manufacturing Specialist | Connect on LinkedIn | Email | www.yunenx.com
✳️ The four-stitch six-thread chain stitch (ISO 607) is synonymous with ‘boneless stitching’ and has become a premium standard in sportswear and lingerie.
🍀 Core Advantages
1️⃣ Ultra High Elasticity
The fabric has a 80% or higher horizontal stretch, significantly better than the 30% of flat-sewn fabrics, and won’t tear even during yoga or squats.
2️⃣ Truly “boneless” body sensation
The seams are less than 0.3 mm thick, with smooth surfaces on both sides for seamless adhesion. The frictionless design ensures no skin abrasion even during intense workouts.
3️⃣ One-piece molding, fast efficiency
With built-in edge trimming and sewing functions, it eliminates the need for two separate processes—first flat sewing and then edge wrapping—achieving a daily output of 2,500 units.
4️⃣ Premium Appearance
The brand is keen to showcase its full, dynamic patterns on the front as a design element.
5️⃣ High strength
Martindale 50: Seam slippage <2 mm after 50 washes; Under Armour compression garments pass 200,000 stretch tests.
6️⃣ Fit high-elastic knit fabric
It is most compatible with challenging fabrics like nylon/aramid and polyester/aramid, resisting wave formation.
🍀 Main shortcomings
1️⃣ Expensive equipment
Japanese heavy-duty machines like the MF-7900 and Yamato models cost RMB30,000 to 50,000 per unit, with an entry barrier 4 to 5 times higher than that of flat sewing machines.
2️⃣ Complex shunting
4 surface wires + 1 bottom wire + 1 tension wire, totaling 6 wires. Even slight deviations in tension or needle bending phase may cause wire jumping or breakage.
3️⃣ High requirements for wire/needle
The wire is too thin to break easily, but too thick to pass through a fine needle. It requires a 70/75 gauge needle with a heat-resistant coating, which increases the cost of auxiliary materials.
4️⃣ Maintenance & spare parts shortage
Accessories such as bent needles and fabric delivery teeth must be original factory parts, with delivery time of 1–2 weeks. If the master craftsman cannot adjust them, production will be suspended for repair.
5️⃣ Restricted style structure
Only “stitching” and “hemming” can not replace the processes of reverse stitching, bag opening, upper sleeve and so on of flat sewing; it still needs the cooperation of various machines.
6️⃣ Unit cost is still higher than three-stitch five-thread/flat sewing
Even if only one process is saved, the comprehensive equipment depreciation, wire material and shunting loss generally make the quotation 25-35% higher.
✅ By mastering these strengths and weaknesses, you can truly leverage the four needles and six threads in the “premium sportswear/fitwear” arena, rather than blindly following trends.
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If you are developing a premium sportswear or activewear brand, we use advanced stitching technologies like 4 needle 6 thread construction to ensure durability, elasticity, and comfort. Contact us for sampling and OEM development.
