A pin-chain steaming-shrinking machine relaxes residual shrinkage under steam mid-line in dry finishing, while a pin-chain frame locks the width at the same time. That release happens before the fabric leaves the mill, so finished garments no longer shrink on their first wash and width no longer drifts batch to batch. QL's WPF-LTYS is built this way, engineered with the QL Anti-Condensate Twin-Steam System, for worsted and woollen dry-finishing lines.
Where this machine sits in the line, and what comes before and after
WPF-LTYS sits mid-line in dry finishing — after singeing or shearing, before decatizing. Next to it, the belt-type steaming-shrinking machine WPF-WDYS is the alternative: the choice comes down to drive method, pin-clamp width-locking versus tension-free belt conveying, which also decides whether weft straightening happens before or after shrinking. An entry spreading roller pre-conditions un-stentered fabric before it enters the pin-clamp zone; once shrinkage is set, fabric moves straight to decatizing — batch, continuous, or pressure decatizing.
What it changes in the fabric, top or yarn: handle, dimensional stability, lustre, cleanliness
What this pin-chain steaming-shrinking machine changes is dimensional stability and surface cleanliness. Weaving and finishing lock stress into the fibre that releases on its own the first time the fabric meets water: relaxation shrinkage, irreversible, present in every fibre fabric. The independent overfeed system feeds in a set length of warp slack so the fabric can relax freely under steam heat, and the pre-delivery cold-suction unit then cool-fixes the result before delivery. The pin-chain frame holds width to the process-defined value from infeed to delivery. On cleanliness, the QL Anti-Condensate Twin-Steam System intercepts condensate at source — a heating bank keeps the steam in vapour state after it crosses the fabric, a suction unit evacuates it immediately, and vapour never dwells on the surface, so the fabric comes off free of water marks and colour spotting.
Why this machine is necessary: what happens without it, or with another method
Skip steaming-shrinking and the relaxation shrinkage does not disappear — it moves downstream to the customer's first wash. Free-belt conveying handles the warp-wise relaxation well enough, but width is unconstrained through the whole steaming and cooling cycle and drifts batch to batch — unworkable for woven qualities with tight width tolerances. Send fabric straight to decatizing without preshrinking first, and decatizing sets the fabric in a dimensional state that still carries unreleased stress.
Setting the parameters: temperature, tension, speed, time
Standard specification: effective working width 1,800 / 2,000 / 2,200 mm, operating speed 30 m/min, steam pressure 4–6 bar, air pressure 8 bar, installed power 23 kW. Warp overfeed — which sets shrinkage depth — steam volume, steam pressure and suction intensity are each configured to the fabric; exact settings are determined by trial — contact QL for the process data sheet. Temperature and tension figures are likewise set by trial for each quality.
The questions customers ask most
- How can under-steaming and uneven shrinkage on heavy-weight woolen double-face fabric be fixed?
- How is fabric protected from water-drip marks and colour spotting caused by steam condensation?
- If garments shrink after just one wash, how can this be fixed before the fabric leaves the mill?
- Belt-type preshrinking can let fabric width drift — how should I choose between the belt type and the pin-chain type?
- Which preshrinking machine should be used for knit fabric — is the pin-chain type (WPF-LTYS) only for woven fabric, or can it handle knits too?
- Is this the same thing as the mechanical pre-shrinking process sometimes used abroad?
Which process routes it appears on
WPF-LTYS's pin-chain steaming-shrinking station appears in the dry-finishing stage of the worsted top-dyed process route, the worsted piece-dyed process route, the woollen stock-dyed process route, and the woollen piece-dyed process route. Related machines include the pin-chain steaming-shrinking machine WPF-LTYS and the belt-type steaming-shrinking machine WPF-WDYS. For technical parameters or selection advice, contact QL Machinery via WhatsApp +1 380 900 2442, or +86 189 2110 8080.