Crabbing Machine
WPF-ZN
Crabbing Machine · Engineered with the QL Single-Bath Reciprocating Setting System
The machine, up close
Full view, rollers visible in the opening
Key advantages
- Single-Bath Twin-Cylinder Reciprocation — the fabric exchanges position pass after pass within one liquor; one heat history for the entire piece, no head-to-tail variation
- Linked Roll Diameters · One Shared Chamber — total wrapper length is constant: as one roll thickens the other thins, and both share a single chamber allowance; a smaller footprint at equal capacity, a higher capacity on equal floor space
- Wrapper-Borne Tension · Zero Fabric Elongation — the wrapper carries the fabric, its tension held constant by torque control throughout; tension never acts on the fabric directly — low tension, zero elongation, knitted wool processed as readily as woven
- Twin-Cylinder Wrapper Centring — both wrapper rolls held centred throughout winding, flare-shaped winding eliminated
Fabric results (before / after)
Threading diagrams
QL Single-Bath Reciprocating Setting System
- Twin-Cylinder Position Exchange — the fabric winds back and forth between two crabbing cylinders, each pass exchanging inner and outer layers — one identical heat history across the piece
- Linked-Diameter Shared Chamber — total wrapper length is constant and the two roll diameters wax and wane against each other; the double-bowl machine's idle allowance — a full roll reserved in each bowl, one side always near-empty — is engineered away. Liquor ratio and footprint fall together
- One Bath, One Temperature — the entire piece stays in a single liquor throughout; no temperature break from bowl-to-bowl transfer
- Fully Immersed Throughout — the fabric remains saturated for the whole of its heating; permanent set forms at the fibre's fullest moisture state
Product overview
The WPF-ZN completes the hot-liquor setting of an entire piece within one bath — a single-bath, twin-cylinder reciprocating structure pioneered by QL carries the fabric back and forth through the same liquor, exchanging position with every pass. The entire piece is set uniformly from end to end.
A single 1,500-litre bowl loads 6–8 pieces of worsted fabric. As the left cylinder winds thick, the right winds thin — the two wrapper rolls wax and wane in step, sharing one chamber allowance. Against the double-bowl machine: a smaller footprint at equal capacity, a higher capacity on equal floor space — and a lower liquor ratio follows.
Suited to the hot-liquor setting of worsted, carded, synthetic-blend and knitted wool fabrics — a flat, even face, lasting lustre, a soft and resilient hand. Placed after scouring and milling, it clears the running marks that rope processing leaves behind; placed after singeing, it washes the fabric clean of singeing ash.
Applications
Key specifications
| Working width | 1,600 mm |
|---|---|
| Wrapper width | 1,800 mm |
| Fabric running speed | 60 m/min |
| Loading capacity | 6–8 pieces of worsted fabric |
| Heating | Direct steam heating |
| Wrapper tension control | Constant-torque tension control |
| Bowl capacity | 1,500 L |
| Installed power | 16 kW (vacuum extractor 4 kW separate) |
| Overall dimensions (L × W × H) | 5,560 × 3,850 × 2,700 mm |
Optional features
- Delivery squeeze / vacuum dewatering system — removes carried liquor at delivery, easing the drying load downstream
- Automatic A-frame batching — roll delivery in place of wagon or saddle plaiting
Full configuration notes, the complete feature list and selection advice — put together for your line and sent straight to you.
Request the full technical fileAll technical parameters stated in this document are measured under ideal operating conditions; actual performance may vary with fabric characteristics, process settings and on-site conditions. The manufacturer reserves the right to introduce technical improvements without prior notice.
Other machines for the same station
This station can be done in more than one way. Each suits a different case — choose by your fabric and output.
Cases with this machine
Mills running the WPF-ZN, and acceptance days.
Common problems in wet finishing
Real questions from the mill floor — and how we answer them.
Should I choose batch crabbing (WPF-ZN) or continuous crabbing (WPF-LXZH) — and is continuous crabbing deep enough?
Both routes deliver a genuine permanent set — the difference lies in production mode and in how depth of set is controlled.
Why must crabbing come before rope scouring or dyeing?
Pre-setting pays off downstream: crabbing before rope scouring and dyeing cuts shrinkage and fuzzing in the stages that follow, the weave staying defined.
Knitted wool cannot take tension — can it still be crabbed?
Yes. The wrapper carries the fabric and its tension is held constant by torque control throughout, so tension never acts on the fabric directly — low tension, zero elongation.
Is crabbing the same thing as decatising or steaming yarn?
Crabbing, decatizing and yarn steaming are three different finishing processes: yarn steaming treats yarn, crabbing sets fabric in hot water, decatizing sets it with steam.
A single-bath machine runs uneven end to end and has to be stopped to turn the piece — output suffers.
No stopping to turn the piece. The fabric winds back and forth between two crabbing cylinders, each pass exchanging inner and outer layers, so one identical heat history runs across the whole piece — no head-to-tail…
A twin-bath machine takes floor space and water we do not have — what then?
A single bowl with two cylinders.
Why must there be a cooling bath — can it be skipped?
No — the cooling bath is the final, required step of crabbing, not an optional add-on.
The fabric face shows water marks, and colour/handle don't match batch to batch — why?
Water marks and batch-to-batch colour mismatch usually trace back to uneven heating inside the crabbing bath — the inner and outer wraps see different temperatures and condensation, so dyeing later shows unevenly.
What can the WPF-ZN do for your line?
Tell us your fabric, weight and output — we will come back with a process proposal and a quotation.