Weft straightening should feed into an operation that maintains the corrected geometry. QL’s Weft Straightening Machine WPF-ZW grips the edges with two freely rotating pin wheels and tensions the fabric symmetrically across its width. On woven routes, its position depends on the pre-shrinking conveyor.
Where this machine sits in the line, and what comes before and after
For pin-chain pre-shrinking on worsted and woollen routes, WPF-ZW straightens first, followed by WPF-LTYS, so the weft is corrected before the edges are held at a fixed width. For the belt route, WPF-WDYS relaxes the fabric first and WPF-ZW straightens afterwards. Both branches then enter decatizing.
WPF-ZW can also be installed at the entry to drying or decatizing equipment for dry or wet woven fabric. The wool-blend knit route shown on this site has no WPF-ZW pin-wheel straightening station.
What it changes in the fabric, top or yarn: handle, dimensional stability, lustre, cleanliness
Weft straightening corrects fabric geometry. Transverse tension brings skew, bow and S- or W-shaped weft deformation back towards a straight alignment perpendicular to the warp. This differs from milling, which develops felting, and pre-shrinking, which releases residual shrinkage.
The two pin wheels on WPF-ZW hold the edges and open symmetrically. Transverse tension is maintained at its setting while wheel opening follows fabric elasticity. Prompt connection to the next operation helps control twisting after garment washing.
Why this machine is necessary: what happens without it, or with another method
The QL Pin-Wheel Transverse-Tension Straightening System uses Ø800 mm wheels, with the large diameter and wrap angle providing transverse stretching conditions. It suits light through heavy woven qualities, including fabrics whose weft is difficult to detect optically. Edge sensing and wheel movement keep the fabric centred, with spreading before pinning.
Driven delivery helps light and loose constructions leave the pins. An adjustable delivery bow roller can pre-set forward or backward bow to compensate for deformation introduced downstream. Review installation with the next machine.
Setting the parameters: temperature, tension, speed, time
Standard WPF-ZW specifications are 1,800 mm working width, 80 m/min maximum speed and 800 mm pin-wheel diameter. Pressure adjustment sets transverse tension, entry and delivery speeds synchronise with the line, and pin plates are selected for the fabric.
Maximum speed is a machine rating, not a recommended speed for every quality. Give QL the construction, width, elasticity, type of weft distortion and downstream equipment to establish pinning, tension and bow-roller settings.
The questions customers ask most
- Why does straightening change position between pre-shrinking methods? Straighten before pin-chain width holding; straighten after the free relaxation of the belt path.
- Can fabric with hard-to-see weft be treated? WPF-ZW straightens through edge grip and transverse tension, including woven qualities with weft that is difficult to detect optically.
- Is the same station included on knits? The knit route here does not include WPF-ZW; assess any knit straightening requirement for the actual process.
Which process routes it appears on
Compare the worsted top-dyed, worsted piece-dyed, woollen stock-dyed and woollen piece-dyed routes. Read about pin-chain and belt pre-shrinking.