Polyester-Lycra knitted fabric combines the structure of polyester yarn with the recovery of an elastane component. One important production setting is how much the elastane is extended during feeding, commonly discussed as elastane draft. Understanding it helps knitters control stretch, recovery force, fabric mass and consistency across repeat orders.
What Elastane Draft Means
Elastane draft describes the relationship between the elastane's substantially relaxed supplied length and the length over which it is incorporated under extension. A simple conceptual ratio is incorporation length divided by relaxed elastane feed length. Real measurements depend on equipment, pre-tension and feed geometry, so the factory should document its chosen definition.
Why Polyester and Elastane Are Fed Differently
Polyester main yarn establishes most of the visible knitted structure. Elastane is usually fed in a controlled extended condition so it can contract after loop formation. These two components can be delivered by separate feeders and guides, and their operating speeds are not necessarily equal.
A Simplified Draft Example
If a defined production section incorporates 3 m of knit path while the corresponding elastane had a relaxed length of 1 m, the conceptual draft ratio is 3:1. This is only a teaching example. The actual effective draft can differ because elastane elongation, friction, pre-tension and relaxation are not perfectly uniform.
How Draft Affects Fabric Stretch
A change in elastane feeding can modify the force required to stretch the knit and its recovery after extension. Higher draft does not automatically provide better comfort or stronger useful recovery; excessive extension can create handling difficulties or poor balance. Evaluate the finished fabric under realistic garment extension.
Relationship with GSM
Elastane contributes mass to the final fabric, but GSM is also governed by stitch length, polyester yarn count, machine settings and post-knitting relaxation. A change in draft may alter relaxed dimensions and therefore measured GSM even if the knitted length produced is similar. Interpret GSM together with width and composition.
Feed Tension Versus True Draft
A tension sensor measures force, while draft relates to extension or delivered length ratio. Because elastane's stress-strain response is nonlinear and affected by running conditions, a stable force does not always prove identical draft. Use the machine's calibrated feeding method and record its operating parameters.
Why Heat Setting Matters
Heat setting stabilizes dimensions within the compatible processing limits of the polyester-elastane blend. It can change the finished width, GSM and recovery behavior observed after knitting. A draft comparison should use material that has received the same finishing and conditioning sequence.
Variations Across Feeders
Different feeders can introduce unequal elastane supply if guides, tensioners or drive settings differ. The resulting polyester-Lycra roll might show stripe-like changes in fabric characteristics. Check feeder-to-feeder consistency rather than judging performance from one short cut swatch.
What to Measure During Trials
Record polyester yarn specification, elastane linear density, feeder mode, measured feed ratios, fabric width, weight and stitch conditions. After processing, evaluate stretch at defined loads, recovery, dimensional change and finished GSM under consistent conditioning.
Troubleshooting Abnormal Stretch
If a roll feels unusually tight, compare elastane feed records and polyester stitch length before assuming the elastane quality is wrong. If extension varies across width or course direction, investigate machine and finishing conditions. A small finished sample may not reveal all feeder variation.
Practical Buyer Specification
For repeat orders, agree on the finished stretch and recovery requirements rather than relying exclusively on an internal draft number. Specify fabric composition, GSM, usable width, shade, conditioning and the stretch test method. The draft record is a manufacturing control setting that helps the mill reproduce approved performance.
Common Questions
Does more Lycra automatically mean more stretch? No; yarn arrangement, draft and structure matter. Is draft equal to elastane percentage? No. Can two rolls with identical GSM feel different? Yes. Is draft recorded only during knitting? It should be linked to finished testing. Can excess draft be repaired by washing? Not reliably.
Conclusion
Elastane draft connects yarn delivery to the eventual behavior of polyester-Lycra knits. The best setting is the one validated for the target fabric construction, usable width, recovery and finishing process—not simply the largest possible numerical ratio.
Related Polyester Manufacturing Guides
For polyester fabric sourcing and manufacturing enquiries, explore Walrus – Yes India Can or contact +91 90420 77722.
