Definition and Core Process
Woven fabrics are formed by interlacing warp (lengthwise) and weft (crosswise) yarns at right angles, producing stable structures like plain, twill, and satin. Warp-knitted fabrics are created by interlocking loops from multiple warp yarns on a warp knitting machine, resulting in structures such as tricot, raschel, and milanese. The key difference: woven relies on interlacing, warp-knit on loop formation. This fundamental distinction dictates all subsequent performance characteristics.
Elasticity and Raveling: Key Procurement Metrics
Elasticity: Woven fabrics typically have 5%-15% stretch, depending on yarn type (e.g., spandex core-spun) and weave density. Recovery is moderate, often losing shape after repeated stretching. Warp-knitted fabrics can achieve 30%-60% stretch, with recovery rates ≥90% (e.g., swimwear warp-knit nylon/spandex). Raveling: Woven fabrics unravel easily when cut or broken, with ravel length often exceeding 10cm. Warp-knitted fabrics resist raveling due to interlocking loops; a single yarn break does not cause widespread unraveling, making them ideal for high-stretch garments.
Application-Specific Selection
Swimwear: Always choose warp-knitted. Requirements: stretch 40%-60%, chlorine resistance, no raveling. Recommended weight: 180-250 g/m² nylon/spandex, tensile strength ≥200N, colorfastness ≥4. Lingerie: Warp-knitted dominates, especially lace and mesh. Needs softness, breathability (≥100 mm/s), and OEKO-TEX® Class 1 certification. Woven is used only for outer layers of shapewear, requiring anti-raveling finishes. Shirts/Outerwear: Woven is standard. Demand tensile strength ≥300N, shrinkage ≤3%, wrinkle resistance ≥3.5 (AATCC). Warp-knitted is unsuitable due to poor drape and snagging.
Procurement Pitfalls and Testing
Myth 1: Warp-knitted is always more expensive. In high-volume orders (≥10,000m), warp-knitting machine speeds (1,000-2,000 rpm) lower unit cost. Myth 2: Woven with spandex equals stretch fabric. Woven stretch is limited (≤15%) and degrades after washing; warp-knitted stretch persists. Testing: Cut 10cm×10cm samples; test tensile strength per ASTM D5034; elastic recovery (stretch 30%, release, measure residual deformation after 5 min); raveling (cut edge, pull yarn, measure ravel length).
Cost and Supply Chain Considerations
Woven: Yarn cost is 60%-70% of total; weaving speed 30-60 picks/min; MOQ often ≥5,000m per color. Warp-knitted: Yarn cost 40%-50%; machine speed 1,000-2,000 rpm; high equipment investment, suited for MOQ ≥10,000m. Advice: For high-stretch, frequent-use garments, choose warp-knitted. For stable, wrinkle-resistant garments, choose woven. Pay attention to finishing: woven requires anti-wrinkle and anti-shrink treatments; warp-knitted needs heat-setting and chlorine-resistant finishes.
Procurement Checklist
- Define end-use: Swimwear/lingerie → warp-knitted; shirts/outerwear → woven; activewear → combine inner warp-knit with outer woven.
- Testing requirements: Woven → tensile strength ≥300N, shrinkage ≤3%; warp-knitted → elastic recovery ≥90%, chlorine resistance (strength loss ≤20% after 24h in 20ppm chlorine water).
- Cost control: Woven small orders → source stock or group orders; warp-knitted large orders → sign minimum volume contracts, negotiate finishing costs (e.g., heat setting).
- Supplier vetting: Request AATCC/ASTM/ISO test reports, OEKO-TEX® or bluesign® certification. Factory audit: For woven, inspect warping and sizing; for warp-knitted, check number of knitting machines and heat-setting equipment.
- Sample approval: Request A4 samples; perform 3 home launderings (40°C, line dry); check dimensional change, colorfastness (≥4), and pilling (≥3.5).
- Contract terms: Specify tolerance (e.g., weight ±5%, width ±2cm), acceptance criteria (e.g., ≤3 defects per 100m), and claim clauses (e.g., ravel length >2cm triggers return).