A continuous crabbing and drying line joins continuous crabbing setting to cylinder drying in a single open-width line. Crabbing sets dimensional stability; tiered cylinder drying removes the glazed face and harsh handle that contact drying can leave on wool fabric. QL's WPF-LXZH is built this way, with a crabbing section and a drying section positioned back-to-back in the wet-finishing stage of worsted and woollen lines.
Where this machine sits in the line, and what comes before and after
The WPF-LXZH joins a continuous crabbing section to a continuous drying section, and the two can run as one line or be selected on their own. Run together, fabric is set in the crabbing section and passes straight into the drying section for a finished dry fabric; selected separately, the crabbing section can hand off to piece dyeing, and the drying section can take wet fabric after hydroextraction or squeezing, or follow an existing continuous crabbing machine. For the crabbing method, this section and the batch crabbing machine WPF-ZN are a choice between two. On woollen routes, wet fabric leaving the crabbing section moves to the WPF-SSMDX wet brushing and setting machine and then on to the WPF-CG teasel raising machine for wet raising, before squeezing and returning to the drying section.
What it changes in the fabric, top or yarn: handle, dimensional stability, lustre, cleanliness
What the crabbing section changes is dimensional stability. The fabric stays fully immersed in hot liquor and is roller-pressed bath by bath, its tension synchronised, before passing through a cold-water bath; that cooling sets the new cross-links formed during crabbing, leaving less distortion, cockling and running marks. The drying section brings tiered temperature control, PTFE-coated cylinders and alternate-face contact together to eliminate the glazed face and harsh handle that conventional cylinder drying can leave on wool. Suction air-cooling before plaiting brings the fabric down in temperature first, reducing stacking creases. With the optional double-face brushing unit and stainless-steel fibre filter, loose fibre and debris are brushed from both faces as well. As for lustre, there is no evidence that the cooling step improves it, so this account makes no claim either way.
Why this machine is necessary: what happens without it, or with another method
Fabric that skips crabbing before rope scouring or dyeing tends to distort, cockle and show running marks. Crabbing is a choice between two methods — single-bath batch crabbing (WPF-ZN) and continuous multi-bath crabbing (WPF-LXZH) — decided by line throughput and the depth of setting needed. Drying wool on conventional contact cylinders, without this section's tiered temperature control, alternate-face contact and PTFE coating, risks a glazed face and a harsh handle; over-drying also takes the fabric below its normal moisture regain, so raising, shearing, pressing and decatizing all need reconditioning first.
Setting the parameters: temperature, tension, speed, time
Line speed runs 5–25 m/min at a working width of 1,600 mm. Five crabbing baths as standard, with the number configured to order; direct steam heating is standard, with indirect heating available as an option. The line divides into several baths rather than one large tank because each bath can be charged with its own liquor for the quality and process, and the fabric is roller-pressed flat bath by bath while remaining in hot liquor throughout. The drying section carries eight cylinders across four tiers, two cylinders to a temperature zone, each tier set independently, with air-cooling before plaiting. Tension is tracked automatically by the vertical dancer and position sensor across the crabbing baths, and is not quoted as a standalone figure; dwell time depends on bath length and line speed, and bath length is not yet published — ask QL for the process sheet. Crabbing temperature and the setting for each drying tier are decided by trial on the actual quality — ask QL for the process sheet.
The questions customers ask most
- Should I choose batch crabbing (single-bath WPF-ZN) or continuous crabbing (WPF-LXZH's continuous crabbing section) — and is continuous crabbing deep enough?
- Can wool be dried on the cylinders of the line's own drying section? Won't the face glaze and the handle turn harsh?
- Do the continuous crabbing section and the continuous drying section have to be bought and run together?
- Why does the continuous crabbing line use five baths rather than one large one?
Which process routes it appears on
WPF-LXZH's continuous crabbing and drying stations appear on the worsted top-dyed process route, the worsted piece-dyed process route, the woollen stock-dyed process route, the woollen piece-dyed process route, and the wool and blend knit fabric process route. Related machines include the Continuous Crabbing and Drying Line WPF-LXZH, the batch crabbing machine WPF-ZN, the wet brushing and setting machine WPF-SSMDX, and the teasel raising machine WPF-CG. For technical parameters or selection advice on the Continuous Crabbing and Drying Line, contact QL Machinery via WhatsApp +1 380 900 2442, or +86 189 2110 8080.