Different fiber lengths depending on nonwoven process, how to choose?

Even if it is the same chemical fiber, if the length changes, the quality of the nonwoven fabric will be completely different.

In this post, I will explain in a simple and clear way which fiber length is appropriate for each nonwoven manufacturing process and why that length is important.

---

What are the characteristics of the fibers used in nonwoven fabrics?

Non-woven fabric (non-woven fabric) is a sheet-like material that is made by intertwining plants rather than weaving them with threads like a dinosaur.

The following are the plants that are generally used with the following specifications:

• Form: Short fiber (staple type)

• Length: Usually 6mm ~ 64mm

• Denier: 1.5D ~ 15D

• Others: Silicone treatment, hollow fiber, heat-melting properties, etc.

The quality of nonwoven fabrics is determined by the physical properties of the fibers and the processing conditions. Among them, ‘fiber length’ plays a key role in process stability and product performance.

---

Appropriate fiber length according to nonwoven manufacturing method

• Wet-laid or air-laid

1. Recommended length : 3mm, 6mm, 12mm

2. Reason : Fibers must be evenly dispersed in water or air, so fibers that are too long will become entangled and clump together, making sheet formation difficult

3. Applications : Wet tissues, sanitary paper, filter media, paper fiber reinforcement, etc.

   
   

• Card & Needle-punch

1. Recommended length : 38mm, 51mm

2. Reason : Because the web is made through carding equipment, fibers of appropriate length are evenly entangled, which is advantageous for maintaining workability and strength

3. Application : Industrial non-woven fabrics, automotive interior materials, architectural sound-absorbing materials, etc.

• Spunlace, Hydroentanglement

1. Recommended length : 38mm ~ 51mm

2. Reason : The method of entangling fibers with high pressure water. If the fibers are too short, they will be pushed out by the water, and if they are too long, they will become entangled. → The middle length is the most stable.

3. Application : Beauty tissues, medical wipes, non-woven fabrics for food, etc.

• Thermal bonding

1. Recommended length : 38mm, 51mm (shorter lengths are also available for Loh-PET fibers)

2. Reason : After web formation, heat is applied to fuse, and fibers that are too long may cause uneven fusion.

3. Application : Cleaning cloth, agricultural cover, filter layer, etc.

   
   

---

Why is length important?

Fiber Length	Advantages	Disadvantages
Short fiber (6–12 mm)	Good for dispersion, uniform web formation	Lacks strength, difficult to card
Medium fiber (38–51 mm)	Stable processability, balanced product strength	Applicable to most processes
Long fiber (64 mm or more)	Excellent bulkiness, soft texture	Risk of entanglement during web formation, not suitable for carding

The performance, productivity and material waste of nonwoven fabrics are already determined by the choice of fiber length.

---

DK FIBER supplies the following polyester staple fibers for nonwovens:

• Length : 25mm / 32mm / 38mm / 51mm / 64mm

• Denier : 1.5D ~ 15D

• Specialized products : low melting point, hollow, siliconized, composite structure fibers, etc.

Custom lengths are available to meet customer process conditions.

Are you looking for the exact fiber specifications for your nonwoven production?

DK FIBER offers polyester fibers with the optimal length and properties to suit your manufacturing process.