What Is Yarn?

The Difference Between Yarn and Thread

The main difference lies in their structure:

• Yarn consists of bundled fibers held together by twist.
• Thread is made by twisting two or more yarns together.

In simple terms, a single yarn usually contains one basic yarn structure, while thread contains multiple yarns twisted together for added strength and stability.

Main Yarn Classification Methods

Yarns can be classified in several ways, including linear density, end use, fiber type, spinning system, appearance, structure, and spinning method.

1. Classification by Linear Density

Yarn count or linear density describes the thickness of a yarn. The classification may vary depending on the counting system used.

Category	Metric Count by Tex	English Cotton Count
Extra-fine yarn	10 tex and below	60s and above
Fine yarn	11–20 tex	29s–58s
Medium yarn	21–30 tex	19s–28s
Coarse yarn	32 tex and above	18s and below

Generally, a lower tex value indicates a finer yarn, while a higher tex value indicates a thicker yarn.

Fine yarns usually create lighter and smoother fabrics. In contrast, coarse yarns often provide greater bulk, strength, and a more textured appearance.

2. Classification by End Use

Different textile products require different yarn properties.

Yarns for Woven Fabrics

Common types include:

• Warp yarns
• Weft yarns
• Pile yarns
• Decorative yarns

Warp yarns need sufficient strength and abrasion resistance because they run through the length of the fabric and experience tension during weaving.

Weft yarns mainly contribute to fabric width, softness, texture, and appearance.

Yarns for Knitted Fabrics

Knitting uses a wide range of yarns, including:

• Weft-knitting yarns
• Warp-knitting yarns
• Pile yarns
• Decorative yarns
• Towel yarns
• Sewing thread yarns
• Embroidery thread yarns
• Household sewing yarns
• Specialty yarns
• Functional yarns

Knitting yarns often require good flexibility, evenness, softness, and suitable friction performance. The exact requirements depend on the knitting machine and final product.

3. Classification by Fiber Type

Yarns can also be classified according to the fibers they contain.

Common categories include:

• Cotton yarn
• Linen yarn
• Staple-fiber yarn
• Filament yarn
• Wool yarn
• Silk-spun yarn
• Blended yarn

Staple-Fiber Yarn

Staple-fiber yarn uses short fibers that require spinning and twisting to form a continuous structure.

Cotton, wool, linen, viscose, and acrylic yarns usually belong to this category.

Filament Yarn

Filament yarn uses continuous filaments. It may contain one filament or several filaments.

Filament yarns often have a smooth surface and can provide good strength, luster, and dimensional stability.

Blended Yarn

Blended yarn combines two or more fiber types. For example, cotton-polyester, cotton-viscose, and wool-acrylic yarns combine the properties of different fibers.

Blending can improve softness, strength, moisture management, warmth, durability, or cost efficiency.

4. Classification by Spinning System

According to the preparation and spinning system, yarns can be divided into:

• Carded yarn
• Combed yarn
• Woolen-spun yarn
• Worsted-spun yarn

Carded yarn retains more short fibers and usually has a slightly rougher appearance.

Combed yarn removes more short fibers and impurities. It produces a smoother, cleaner, and more even yarn.

Woolen-spun yarn normally has a fuller, softer, and more bulky structure. Worsted-spun yarn usually has a smoother surface, better alignment, and a cleaner appearance.

5. Classification by Appearance and Structure

According to their appearance and structure, yarns include:

• Single yarn
• Plied yarn
• Monofilament yarn
• Multifilament yarn
• Bulked yarn
• Textured yarn
• Core-spun yarn
• Fancy yarn
• Slub yarn
• Twistless yarn
• Wrapped yarn
• Covered yarn

Each structure creates a different surface effect and performance profile.

For example, core-spun yarn can combine a strong core with a soft outer fiber. Slub yarn creates intentional thick and thin sections. Fancy yarn uses special structures or color combinations to create decorative effects.

6. Classification by Spinning Method

Ring-Spun Yarn

Common ring-spun yarn types include:

• Conventional ring-spun yarn
• Compact-spun yarn
• Siro-spun yarn

Ring spinning generally produces yarns with good strength, flexibility, and a relatively natural hand feel.

Compact spinning reduces fiber hairiness and improves yarn smoothness. Siro spinning combines two strands during the spinning process and can create a cleaner and more stable yarn structure.

Open-End and Other Spinning Methods

Other spinning methods include:

• Rotor spinning
• Air-jet spinning
• Dust-cage spinning
• Electrostatic spinning
• Self-twist spinning
• Composite spinning

Each method has its own advantages in production speed, yarn structure, strength, hairiness, uniformity, and end use.

The Main Spinning Process and the Role of Each Stage

The spinning process usually includes fiber blending, opening, cleaning, carding, combing, drawing, roving, and final spinning.

Each stage prepares the material for the next one. The quality of the final yarn depends on the coordination of the entire process.

1. Cotton Blending

Cotton blending involves selecting and mixing different batches or types of fibers before spinning.

Main Purposes

The main purposes include:

1. Meeting the required yarn quality.
2. Maintaining stable production.
3. Making full use of different raw-material properties.
4. Controlling production cost in a reasonable way.

Different cotton lots may vary in fiber length, strength, fineness, maturity, moisture, and impurity content. Proper blending helps reduce these differences and improves production consistency.

2. Blending Methods

Common blending methods include:

Manual Blending

Workers mix different fiber materials according to the production formula.

This method offers flexibility, but the result can depend heavily on operating accuracy and mixing conditions.

Bale Blending

The production team opens different cotton bales and arranges them according to the required blending ratio.

This method supports larger-scale production and provides better control than simple manual mixing.

Sliver Blending

The process blends fibers after they have already passed through part of the opening and carding stages.

Sliver blending can provide more accurate control and improve the uniformity of the final blend.

3. Opening, Cleaning, and Blending

This stage usually takes place in the blowroom.

Opening

Opening loosens compressed fiber bales into smaller fiber tufts or fiber bundles.

The process changes large, compact blocks into smaller pieces that the following machines can process more effectively.

Cleaning

Cleaning removes larger impurities, visible defects, and foreign matter from the fiber material. The opening and cleaning process may remove approximately 60% of the larger impurities.

Blending

Blending combines fibers with different properties and specifications to create a more uniform material.

Forming a Uniform Fiber Lap

The machine forms a semi-finished product with a relatively stable structure. This product may appear as a fiber lap or a continuous fiber stream.

A typical fiber lap may have the following reference values:

• Length: approximately 34.2–43.2 meters
• Weight: approximately 16–20 kg

The dry mass per unit length may vary by yarn count:

• Coarse yarn: approximately 420–450 g/m
• Medium yarn: approximately 390–420 g/m
• Fine yarn: approximately 360–390 g/m
• Extra-fine yarn: approximately 320–360 g/m

4. Carding

Carding prepares the fiber material for further processing.

Main Functions of Carding

1. Fiber separation: The machine separates fiber tufts into individual fibers as much as possible.
2. Impurity removal: It removes small impurities and fiber defects.
3. Fiber blending: It distributes the fibers more evenly.
4. Sliver formation: It gathers the fibers into a continuous strand called carded sliver.

The machine coils the carded sliver into a can so that the next process can unwind it smoothly.

Reference Dry Mass of Carded Sliver

• Yarn above 32 tex: approximately 22–28 g/5 m
• Yarn from 20–30 tex: approximately 19–26 g/5 m
• Yarn from 12–19 tex: approximately 16–24 g/5 m
• Yarn of 11 tex and below: approximately 16–22 g/5 m

Carding has a major influence on fiber alignment, yarn evenness, nep content, and final yarn quality.

5. Combing

Combing provides a more precise treatment after carding.

The process improves fiber alignment, removes additional impurities, and produces a cleaner and more uniform combed sliver.

Main Functions of Combing

1. Fine fiber alignment: Combing straightens, separates, and aligns the fibers more effectively.
2. Short-fiber removal: It removes fibers below a certain length, generally around 16.5 mm.
3. Nep and impurity removal: It removes cotton neps and other small defects.
4. Sliver formation: It creates a combed sliver with a more uniform structure.
5. Regular coiling: It places the combed sliver into cans for the next process.

Combing can increase the parallel alignment of fibers from around 50% in carded sliver to approximately 90%.

The short-fiber removal rate may reach around 45%, depending on the raw material and process settings.

Reference Dry Mass of Combed Sliver

• Extra-fine yarn: approximately 10.5–14 g/5 m
• Fine and medium yarn: approximately 13.5–15.5 g/5 m
• T/C blended yarn: approximately 18.5–21 g/5 m

Combed yarn usually provides a smoother appearance, better strength, lower hairiness, and improved surface cleanliness.

6. Drawing

Drawing combines several slivers and then drafts them to improve uniformity.

Main Functions of Drawing

1. Combining: The machine combines approximately 6–8 carded or combed slivers.
2. Drafting: It stretches and reduces the thickness of the combined sliver.
3. Blending: Repeated combining and drafting improve fiber mixing.
4. Straightening: Drafting further aligns and straightens the fibers.
5. Sliver formation: The machine forms a sliver with a controlled weight and coils it into a can.

When several slivers come together, thick and thin places can compensate for each other. As a result, drawing improves the evenness of the material.

Reference Dry Mass of Drawn Sliver

Typical reference values include:

• Yarn above 32 tex: approximately 19–23 g/5 m
• Yarn from 20–30 tex: approximately 15–20 g/m
• Yarn from 13–19 tex: approximately 13–18 g/5 m
• Yarn from 9–13 tex: approximately 11–15 g/m

The number of drawing passages depends on the fiber type, yarn count, blending ratio, and quality requirements. Pure cotton and blended fibers may require different drawing arrangements because their lengths, friction, and drafting behavior can vary.

7. Roving

Roving prepares the drawn sliver for final spinning.

Main Functions of Roving

1. Drafting: The machine stretches the drawn sliver by approximately 5–12 times. Some imported roving frames may use a drafting range of around 2.5–24.2 times.
2. Straightening: Drafting further aligns the fibers.
3. Twisting: The machine adds a small amount of twist to give the roving enough strength for winding and transport.
4. Winding: The machine winds the roving into a stable package for the final spinning process.

The roving twist may range from approximately 2.13 to 1.01 turns per 10 cm, depending on the yarn count and process design.

Reference Dry Mass of Roving

• Yarn above 32 tex: approximately 5.5–10.0 g/10 m
• Yarn from 20–30 tex: approximately 4.1–6.5 g/10 m
• Yarn from 9–19 tex: approximately 2.5–5.5 g/10 m
• Yarn of 9 tex and below: approximately 1.6–4.0 g/10 m

Traditional Multi-Stage Roving

Older roving systems may use two or even three roving stages, especially when producing high-count yarn.

A typical process may include:

• First roving: A single cotton sliver enters the machine and receives approximately 3–4 times mechanical drafting. The machine produces first-stage roving of around 660–1,250 tex.
• Second roving: Two first-stage rovings enter the machine and receive approximately 4–5 times mechanical drafting. The machine produces second-stage roving of around 230–650 tex.
• Third roving: Two second-stage rovings enter the machine and receive another 4–5 times mechanical drafting. The machine produces third-stage roving of around 100–220 tex.

Modern equipment may combine or simplify these steps, depending on the spinning system and product requirements.

8. Final Spinning

Final spinning creates the finished yarn.

Main Functions of Final Spinning

1. Drafting: The machine drafts the roving to the required yarn count.
2. Twisting: It adds twist to provide the finished yarn with the required strength and stability.
3. Winding: It winds the yarn onto a suitable package for later processing and use.

The drafting ratio in the final spinning process generally ranges from approximately 10 to 50 times.

The spinning frame controls the final yarn count, twist, strength, evenness, hairiness, and package form. These properties directly influence the performance of the yarn during weaving, knitting, dyeing, and finishing.

Conclusion

Yarn classification helps textile professionals understand the differences between yarn types, structures, fiber compositions, and production methods.

The spinning process also involves several closely connected stages. Blending determines the raw-material combination, opening and cleaning prepare the fibers, carding separates and aligns them, combing improves fiber quality, drawing increases evenness, roving prepares the material for final spinning, and final spinning creates the finished yarn.

Each stage affects the next one. Therefore, stable yarn quality depends on the coordination of raw materials, machinery, process settings, and quality control.

By understanding yarn classification and the purpose of each spinning stage, beginners can better evaluate yarn specifications, select suitable materials, and communicate more effectively during textile product development.