Fabric Manufacturing / Weaving and Knitting
This domain tests loom motions in order, weave structure identification, knitted loop formation and fabric geometry calculations such as cover factor, ends/picks per inch and areal weight. You should be able to say what a weave repeat, a float and a stitch length are and why they change fabric properties.
Loom motions
- Primary: shedding (divides warp into two sheets), picking (inserts weft), beat-up (pushes the pick to the fell).
- Secondary: let-off (delivers warp at tension) and take-up (draws fabric forward).
- Auxiliary: warp stop, weft stop, temples, selvedge devices.
- Shed selection by crank/tappet (simple weaves), dobby (small repeats) or jacquard (large, individual end control). Weft insertion may be projectile, rapier, air-jet (very high speed) or water-jet (filament yarns).
Structures and geometry
- Plain 1/1: maximum interlacing, firmest, shortest floats. Twill shows a diagonal from staggered floats. Satin has long floats, high lustre, low interlacing and poor abrasion resistance.
- Warp runs lengthwise, weft across. EPI and PPI set tightness; cover factor combines count and sett.
- Knitting: weft knitting (single jersey, rib, interlock) runs yarn across the width; warp knitting (tricot, raschel) supplies one yarn per needle along the length. Gauge = needles per inch; stitch length controls GSM and extensibility.
Worked example
Fabric: 100 EPI, 40s Ne warp, 5% crimp; 80 PPI, 40s Ne weft, 8% crimp. One square metre has 39.37 × EPI ends of 1 m each, and 1 m of 40s cotton yarn weighs 0.5906/40 g. Warp = 39.37 × 100 × 0.5906/40 × 1.05 = 61.0 g. Weft = 39.37 × 80 × 0.5906/40 × 1.08 = 50.2 g. GSM = 61.0 + 50.2 ≈ 111 g/m².
Traps
- Putting beat-up before picking in the cycle.
- Reversing let-off and take-up functions.
- Confusing CPI with knitting gauge, or warp with weft in weight formulae.
- Forgetting crimp allowan