All About Yarn: A Comprehensive Guide fron Front-Line Expert

In the textile industry, yarn is the most basic element to start with any type of production or Research & development. All fabric properties depend on yarn material, count, strength and weave ability. In this article, you will learn everything about types of yarn and how it’s processed from natural or man-made fibres.

What is Yarn?

A yarn is a continuous string of fibers (naturally or man-made) arranged in a way appropriate for the fabric manufacturing process. All fabrics, except non-woven fabrics, are produced using yarns as the fundamental component. Yarns are held together due to their unique molecular structure, comprising a variety of scales that help them bind together. Fibers are also twisted during spinning, which results in a continuous length and the desired coarseness.

Yarn always serves as the bridge between fiber and fabric, making it one of the most important intermediate products in the universe of textile manufacturing chain, and the performance of the finished article significantly depends on the quality of yarn, which is used during production. Each and every textile engineer must know that a strong and even yarn produces fabric with better durability and appearance, while a poor quality yarn can lead to different defects, including uneven dyeing, fabric streaks, excessive pilling and frequent breakage of yarn during weaving or knitting, and for this reason, the yarn manufacturers place great emphasis on maintaining the consistent quality during the spinning process.

Where does yarn come from?

Yarn can be classified by the origin of the raw material. Yarn can be categorized as

1. Plant Fibers

Plant fibers are ideal for their lightweight and breathability. They have been used in clothing for ages. They are also environmentally friendly and biodegradable. Cotton, flax, linen, hemp, jute, bamboo, and banana are examples of plant fibers.

Plant fiber is gaining popularity due to the growing demand for sustainable, eco-friendly textiles, and modern spinning technologies have improved the quality and consistency of yarn from natural fibers, enabling manufacturers to produce finer, stronger yarn than ever before. Several regenerated cellulosic fibers, such as lyocell, modal and viscose, have been developed to combine the environmental advantages of cellulose with improved mechanical performance.

2. Animal Fibers

These yarns are made from animal hair, like sheep or extracted from cocoons, like silk. These are more durable and warmer than plant fibers. Depending on the breed of animal, yarn may have a variable texture. The most widely used animals for yarn production include sheep, silkworms, alpacas and goats.

3. Synthetic Fibers

These fibers are composed of synthesized polymers. These fibers are made up of different chemicals; therefore, each yarn has different properties. These are frequently less expensive than natural fibers. These yarns are easily dyed, typically long-lasting, and require less care than natural fibers. They can be manufactured according to end-use. Commonly used synthetic fibers include Viscose, Polyester, Acrylic and Nylon.

4. Blended Yarns

These yarns are made by blending two or more yarns. These yarns are highly recommended for their combined properties. The most commonly used blends are Polyester-cotton (PC), Wool-nylon, and Cotton-Viscose.

Blending of fibers has become one of the most important practices in modern textile manufacturing because none of a single fiber can satisfy each and every performance requirement, for example, blending of cotton with polyester combines the comfort and moisture absorbency of cotton with the durability and wrinkle resistance of the polyester and adding a small percentage of elastane can improve the stretch and recovery of the fabrics without affecting their appearance.

Yarn Manufacturing Process

The process of yarn manufacturing is known as spinning. Spinning involves all processes from raw material. i.e. fibre to yarn. It includes a number of processes. The following is a brief and comprehensive overview of the cotton yarn process

• Blow Room

Cotton in the form of compressed bales is opened in this process. It also cleans cotton from its seeds, leaves and other substances.

• Carding

This machine has a big drum with spikes on the surface. It opens cotton into its individual fibers, which are then aligned and named slivers. This machine is also known as the heart of spinning.

• Draw Frame

It aligns the silver more parallel by drafting. Fibers in this stage are straighter than the carding process.

• Speed frame

It gives a sliver twist for strength. At this stage, the sliver is changed into roving.

• Ring

This is the final stage. Roving is twisted to the required yarn count.

• Auto cone

Yarn is then wrapped into cones according to the requirement.

The above process is known as ring spinning. Other spinning techniques include rotor spinning, air vortex spinning and electrostatic spinning.

Characteristics of yarn

Yarn Count

Yarn thickness or coarseness is known as yarn count. A yarn count indicates mass per unit length or length per unit mass. There are 2 types of systems to measure yarn number.

• Direct or Universal System

In this system, the count of yarn is based on units of weight per unit length of yarn. It is accepted worldwide. It is denoted by Denier, Tex.

• Indirect System

In this system, the count of yarn is based on the number of units of length per unit mass of yarn. It is denoted by Ne.

It should be kept in mind that the two systems above are inverses of each other. In a direct system, the number increases as the yarn becomes coarser. In an indirect system, the number gets smaller as the yarn gets coarser.

For a general idea and conversion, 1 Denier = 5315 / Ne.

Selecting the correct yarn count is very important throughout textile manufacturing because it influences almost every stage of production. During weaving, yarn count affects the strength of the warp, the efficiency of the loom, and the construction of the fabric. In knitting, it determines the size of the loop, the weight of the fabric and its elasticity. Different types of textile products require different yarn finenesses, so manufacturers must carefully select the yarn count based on the intended end use, production process and the customer’s specifications. That is the main reason why accurate yarn count testing is important for quality control activity and every textile lab.

Yarn Twist

The fibres in the yarn are held together by stretching and twisting around the axis. This process is very important in the spinning industry, as yarn appearance, strength, and hand feel depend on it.

Yarn twist is important as it binds fibers and adds strength to the yarn. For 2-ply or 3-ply yarn, the plies are also twisted together to form a single yarn.

Generally, low-twist yarns are ideal for knitting, producing soft, bulkier fabrics, whereas weaving requires high-twist yarns. This is denoted by TPI (Twist per Inch).

There are two types of twist direction

• S-Type Twist

In this type, filament appearance around the yarn axis resembles the letter “S”.

• Z-Type Twist

In this type, filament appearance around the yarn axis resembles the letter “Z”.

The direction of the yarn twist influences the performance of spinning, the construction of the fabric and the properties of the final product. Z twist is the standard twist direction for most single yarn because it provides clear and smooth processing while spinning, weaving and knitting, and S twist is mainly used in ply yarns, carpet fabrics, sewing threads and specialty textiles to balance skew, improve the stability of the fabric and achieve the specific appearance or performance requirements.

Specialty Yarns

Speciality yarns are made for specific purposes and specialized needs. They have distinct physical and visual qualities that distinguish them from ordinary yarns. Designers and R&D personnel frequently use these yarns to create customized fabrics and garments.

These yarns, for instance, can be designed for anti-microbial and moisture-wicking qualities for controlling perspiration, such as in sportswear.

The following are some special yarns with various properties.

• Chenille Yarn

It has a soft, feathery and velvety texture that creates a plush look when sewn onto a backing fabric.

• Faux Fur

It is a pile of fabric that resembles real animal fur. It is made from a blend of polyester, mod-acrylic, and acrylic fibers.

• Metallic Yarn

It is a synthetic yarn with a metallic appearance. Certain metal components increase their tensile strength while also giving them a glossy appearance. Transparent films can be applied to metallic filaments to reduce tarnishing. Metallic filaments are used to create intricate patterns and designs in fabrics such as brocades and jacquards.

• Boucle Yarn

It is a type of ply yarn in which a yarn with high tension and a short length is twisted with low tension and a longer length of yarn. Boucle yarn features loops or loose strands, making it ideal for adding texture and enhancing the aesthetic of fabrics.

Colors of Yarn

In yarn dyeing, dye pigments are penetrated into fibers. Mostly, it is done for solid shades. It is done in different ways

• Package Dyeing

One of the most popular techniques for dyeing yarn is package dyeing. In this process, yarn is loosely wound over spindles containing hollow spaces. The dye liquor is passed through these perforated holes into the yarn. These packages are placed inside a dye liquor bath at a high temperature. It is also known as cone dyeing.

• Skein Dyeing or Hank Dyeing

In this process, large skeins of loosely wound yarn are immersed in dye machines designed specifically for this process. It is a relatively costlier dyeing technique.

• Beam Dyeing

This is similar to package dyeing but on a larger scale. Whole warp beams are wound over a perforated cylinder and then dyed. This type of dyeing is used in the weaving process, where an entire beam must be dyed a single colour. Other techniques are used in the knitting process.

• Space Dyeing

This type of dyeing gives yarn a multi-color effect, which may or may not repeat after intervals.

Testing of Yarn

In the textile lab, yarn is tested for various reasons. Quality testing ensures process and product control and increases productivity with less waste. It is also necessary to check the quality of yarn before running it in the production process. In a fabric testing laboratory, quality checks involve the following tests, including

• Yarn composition (Fiber Content)
• Yarn count
• TPI and TM
• Short Fiber Index (SFI)
• Yarn strength and Lea strength
• Yarn moisture percentage
• Yarn crimp percentage

Conclusions

Yarn is the fundamental building block of the textile industry and directly influences product quality, performance and durability. Understanding the different parameters of yarn, including types, manufacturing processes, characteristics, dyeing methods and testing requirements, helps manufacturers to produce textiles that meet both quality standards and customer expectations. From fiber selection to the final spinning stage, each and every process contributes to getting the desired yarn properties and regular lab testing of yarn count, twist, strength and other quality parameters helps to ensure the consistency, reduces the defects of the production and improves the efficiency.

FAQs

What is yarn made of?

Yarn is made from small fibers of varying lengths and origins. In man-made yarns, filaments are used.

How to tell the weight of yarn?

Yarn is identified by its Count. A yarn count indicates mass per unit length or length per unit mass. It can be either in a direct or indirect system. A wrap reel machine is also used in fabric testing laboratories to measure accurate length and calculate yarn count.

Why is yarn twist important?

Twisted is needed due to the following reasons

1. To achieve the required count. i.e. (yarn diameter)
2. To increase the fiber bonds with each other so that the yarn does not open easily.
3. To increase the tensile properties of yarn.

What is the softest yarn?

In natural fibers, cashmere and merino wool yarns have a softer texture than other types of yarn. In man-made fibers, acrylic yarns are relatively soft.

What is the most durable yarn?

Yarn of animal origin, especially wool, is durable for a lifetime. Additionally, high-performance fibers such as Kevlar and Dyneema are manufactured to meet end-use requirements.

Give a brief comparison of acrylic vs cotton yarn.

Both Cotton and Acrylic are multipurpose yarns that can be utilized in different end products. However, both have special qualities and advantages over each other that can make them more specific for a particular use. The following is a brief comparison of both yarns

What is the best yarn for knitting?

For knitting, yarn with a low twist is ideal. Low twist leads to bulkier and softer yarn, which eventually reflects in knitted garments.

What are the types of wool for crochet?

Natural wool yarn is ideal for crochet making, as it has environmental benefits, characteristics, and texture. When choosing the right yarn, choose a yarn with a smooth surface and fewer protruding fibers, as these fibers entangle with each other and cause pills. Also, choose the colour according to your choice.

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