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Spinning (fiber formation) is the starting point of every man-made fiber — and the core of fiber performance design. This guide walks you through the four major spinning methods: melt spinning, wet spinning, dry spinning and dry-jet wet spinning, covering their principles, process flows and suitable polymers. Then we match each route with the right laboratory solution from Anytester: the AT225 Lab Melt Spinning Machine and the AT235 Bench-top Wet Spinning Machine. A ready-to-use RFQ checklist and email template are included at the end, so your first inquiry returns an accurate quotation.
Spinning, or fiber formation, is a process in which the spinning fluid (dope or melt) is continuously, precisely and uniformly extruded through a spinning pump (also called a metering pump) to form liquid filaments, which are then solidified into yarn in air, water or a coagulation bath.
According to how the spinning fluid is prepared and solidified, chemical fiber formation falls into four major categories: melt spinning, wet spinning, dry spinning and dry-jet wet spinning (air-gap spinning). Which method to choose depends on whether the polymer can be melted, whether it can be dissolved, and the performance targets of the final fiber. Let's look at each one.
In melt spinning, the polymer is heated to a molten state and extruded through the spinneret holes; in air, the molten fluid gradually cools and solidifies into fibers. The polymer used must melt into a viscous flow state without significant decomposition. Polyester (PET), polyamide (PA) and polypropylene (PP) fibers are all produced by melt spinning.
Melt spinning offers outstanding advantages: spinning speeds as high as 1,000–7,000 m/min; no solvents or precipitants are needed, so there is no solvent recovery system, the equipment is simpler and the process flow is much shorter — an economical, easy-to-operate and highly efficient production method.
Process flow: chips of the fiber-forming polymer, after pre-crystallization and drying, are melted, mixed, metered and extruded in the separately heated zones of a screw extruder. The melt is fed precisely by the melt metering pump into the spinning manifold, extruded through the spinneret into fine molten streams, and solidified at lower temperature under cooling air to form the as-spun fibers. The fibers are then finished (oil application, interlacing), wound onto bobbins, and finally converted into usable fibers through drawing and heat setting.
Direct spinning vs. chip spinning: by melt preparation, melt spinning has two routes. In direct spinning, the polymer melt from polymerization is fed directly to the metering pump — cost-effective and dominant in industrial production, but less flexible for differentiated fibers (mainly adjustable in linear density and cross-section). In chip spinning, granules are pre-crystallized and dried, then melt-spun through a screw extruder — easier for product changeover and ideal for small-batch, high-value differentiated fibers, which is exactly where a laboratory melt spinning machine shines.
In wet spinning, the polymer is dissolved in a solvent to form the spinning dope, which is extruded through the spinneret into a coagulation bath, where the polymer precipitates as solid filaments. This method is particularly suitable for fiber-forming polymers whose decomposition temperature is below their melting point or that discolor on heating, yet can be dissolved in a suitable solvent. Acrylic (PAN), vinylon (PVA) and other synthetic fibers, as well as man-made fibers such as viscose and cuprammonium rayon, are produced by wet spinning.
Characteristics: wet spinning is relatively slow, but the spinneret has far more holes than in melt spinning; the process is more complex and the cost higher. Due to solidification in the bath, the fiber cross-section is usually non-circular with a distinct skin-core structure. To compensate for the low speed, staple fiber production uses multi-hole or clustered spinnerets.
Process flow: prepare the spinning dope → filter and extrude through the spinneret into fine streams → coagulate in the bath to form as-spun fibers → wind or directly after-treat to obtain the final product.
Dry spinning suits polymers for which a low-boiling, highly dissolving solvent can be found: the spinning solution is extruded through fine holes into a heated gas stream; as the solvent evaporates, the polymer filaments solidify. After drawing, setting, washing and drying, the finished fiber is obtained. Acrylic, spandex, PVC (chlorofiber) and vinylon fibers are produced by dry spinning.
Characteristics: dry spinning features continuous production, high spinning speed, large output and low pollution. The fibers are superior to wet-spun fibers in quality, chemical resistance and dyeability. However, dry-spun fibers have poorer chlorine resistance, the technology is more demanding, and solvent recovery is required — so production costs are relatively high.
Dry-jet wet spinning, also called dry-wet spinning or air-gap spinning, is a unique solution-spinning method that combines the advantages of wet and dry spinning. It is particularly suitable for processing liquid-crystal polymers, and is therefore also known as liquid-crystal spinning.
The spinning solution is extruded through fine holes and first passes through an air gap, where the resistance is low and the liquid-crystal polymer molecules become highly oriented under high draw ratios. The filament then enters a low-temperature coagulation bath to solidify, freezing in the highly ordered liquid-crystal structure. The resulting fibers exhibit high strength and high modulus. The method is now widely used for PAN fiber, polylactic acid (PLA) fiber, chitosan fiber and more.
Characteristics: suitable for high-viscosity spinning dopes, with easy solvent recovery and low unit consumption; fast formation, uniform fiber structure, and a nearly circular cross-section, giving significantly improved strength and elasticity as well as excellent dyeability and luster. Drawbacks: after filament breakage the dope tends to overflow along the spinneret face, and in multi-hole spinning a single broken filament may cause neighboring filaments to break, disrupting spinning continuity.
| Method | Solidification | Spinning Speed | Hole Count | Typical Fibers | Key Features |
|---|---|---|---|---|---|
| Melt spinning | Cooling in air | 1,000–7,000 m/min | Relatively few | PET, PA, PP | Solvent-free, short flow, economical and efficient |
| Wet spinning | Precipitation in coagulation bath | Low | Many (tens of thousands for staple) | PAN, vinylon, viscose, cupro | Non-circular section, skin-core structure, complex flow |
| Dry spinning | Solvent evaporation in hot air | Faster than wet, slower than melt | ~1,200 | Acrylic, spandex, PVC, vinylon | Better quality and dyeability; solvent recovery needed |
| Dry-jet wet spinning | Air-gap orientation + coagulation bath | Relatively fast | Depends on product | PAN, PLA, chitosan, LCP fibers | High strength & modulus, near-circular section, uniform structure |
An industrial line is tens of meters long and represents heavy investment. For new product development, process exploration and trial production of differentiated fibers, laboratory-scale spinning equipment is indispensable. Anytester (Hefei) Co., Ltd. offers dedicated bench-top solutions for the two most typical routes:
PETPAPPThermoplastic polymers
The AT225 is a key machine for synthetic fiber research. It uses high-temperature copper ring blocks to heat and melt the polymer sample, and extrudes the melt as a liquid trickle from the spinneret under inert gas (N₂) pressure to produce the nascent fiber. The machine consists of a melting system, a spinning system and a winding system — ideal for spinnability evaluation, chip screening and process parameter studies.
Key features:
Technical specification:
| Item | Specification |
|---|---|
| Model | AT225 |
| Pressure range | Max. 2 MPa (extendable to 3.6 MPa); input ≤13 MPa, output ≤1.5 MPa; accuracy ±0.01 MPa |
| Temperature range | Max. 350℃; accuracy ±0.5℃ |
| Heating mode | Three heating sections with copper ring blocks; mullite fiber insulation |
| Temperature control | Three independent zones, accuracy ±0.5℃ |
| Feed cylinder | 500 ml, stainless steel, with soaking distribution device |
| Spinneret plate | Hole dia. 0.15–0.5 mm; L:D 2:1–3:1; 1–20 holes (please specify before order) |
| Winding system | Motor-driven; 0–1,400 rpm adjustable; winding roller dia. 200 mm (customizable); max. winding dia. 320 mm |
| Power supply | AC220V, 50Hz |
| Dimensions | 870×1310×1860 mm (D×W×H) |
| Weight | Approx. 320 kg |
Standard configuration: main machine, spinneret plate (on machine), winding roller (on machine), distribution plate (on machine), 10 filtering plates, gas inlet pipe, special spanner, temperature sensor (1 spare), packing list, quality certificate, user manual. Optional: spinneret plate, winding roller, filtering plate, temperature sensor.
PANVinylonViscoseNovel fibers
The AT235 is specially designed for researching new materials in the fields of textiles, macromolecules and beyond. It can simulate the whole wet spinning process: the line consists of a spinning solution tank, dosing pump, gooseneck, spinneret, coagulating bath, drawing rollers, heating slot, setting slots and winding roller — all connected by quick joints for easy assembly.
Key features:
Technical specification:
| Item | Specification |
|---|---|
| Model | AT235 |
| Spinning solution tank | 1 L or customized; 316L stainless steel; rapid-mount cover with nitrogen inlet port and vent port |
| Sample volume | 200–600 ml or customized |
| Dosing pump | Flow rate 0.66 CC/rev; power 60 W; reducer 1:60 |
| Gooseneck | 316L stainless steel |
| Spinneret | 1 spinneret; spinneret nut 100 holes, hole dia. 0.07 mm, material: tantalum |
| Coagulating bath | Inner size 1000×160×160 mm (L×W×H); 316L stainless steel; two filament pressing rollers; optional heating system |
| Drawing rollers | Nylon; Ø50×80 mm; reducer 1:10; motor 120 W; roller speed 3–40 m/min adjustable |
| Heating slot | Non-contact; length 400 mm; heating power 750 W; temp. room temperature–250℃; PT100 |
| Setting slots | Non-contact; length (400×2) mm; heating power 750 W×2; temp. room temperature–250℃; PT100 |
| Winder | Speed 3–40 m/min; roller Ø95×80 mm; transverse displacement 60 mm |
| Whole line length | 5000 mm |
| Power supply | AC220V, 50Hz, single-phase |
Standard configuration: main machine, spinneret plate, packing list, quality certificate, user manual. Optional: heating system for coagulating bath.
An RFQ (Request for Quotation) is the first step of procurement. A complete RFQ allows the supplier to return an accurate quotation and delivery time immediately, without rounds of clarification. We recommend sending your inquiry along the following checklist:
RFQ email template (copy and paste):
Subject: RFQ - AT225 Lab Melt Spinning Machine Dear Anytester Team, We are interested in your AT225 Lab Melt Spinning Machine and would like to request a quotation. - Polymer to be spun: e.g. PET / PA / PP - Spinneret: hole dia. ___ mm, ___ holes, L:D ___ - Max. spinning temperature required: ___ deg C - Quantity: ___ set(s) - Destination port / country: ___ - Trade term required: EXW / FOB / CIF ___ Please also advise the delivery time and warranty terms. Best regards, ___ (Name / Company / Country)
Email: sales@anytester.com | Tel/WhatsApp: +86 188 5510 5986 | Web: www.anytester.com
Whether it is spinnability evaluation by melt spinning or novel fiber exploration by wet spinning, Anytester has the right laboratory spinning solution for you.
Anytester (Hefei) Co., Ltd.
Add: No. 128, Danxia Road, Shushan District, Hefei City, Anhui 230601, China
Email: sales@anytester.com | Tel: +86 188 5510 5986
