What Factors Affect Fabric Width? Tips for Controlling Width During Production

Controlling fabric width during processing is one of the key indicators in textile production.

Among the various factors, fabric design has the most direct impact on the final width of the product. Factors such as loom width, reed type, fiber fineness, fabric weave structure, and warp and weft density all directly affect the finished width.

For example, polyester woven fabrics commonly include plain fabrics, high-twist faux silk fabrics, stretch fabrics, and wool-like blended fabrics. Additionally, dyeing and finishing processes significantly influence fabric width.

1. Impact of Process Flow

Different fabric types require specific dyeing and finishing workflows:

For regular plain fabrics: Preparation → Scouring → Dyeing → Post-treatment → Dehydration → Drying → Setting → Inspection

For high-twist faux silk fabrics: Preparation → Preshrinking → Pre-setting → Alkali reduction → Washing → Dyeing → Post-treatment → Dehydration → Drying → Setting → Inspection

For stretch fabrics: Preparation → Open-width scouring → Preshrinking → Pre-setting → Dyeing → Post-treatment → Dehydration → Drying → Setting → Inspection

For wool-like blended fabrics: Preparation → Singeing → Preshrinking → Pre-setting → Dyeing → Post-treatment → Dehydration → Drying → Setting → Steam-boxing → Inspection

The primary processes for dyeing and finishing polyester woven fabrics typically include 12 key steps: preparation, scouring, preshrinking, pre-setting, alkali reduction, dyeing, post-treatment, dehydration, drying, setting, steam-boxing, and inspection.

2. Impact of Processing Steps

① Fabric Preparation

The main tasks during preparation include marking, sewing, and weighing.

The resting time of fabric rolls after unwinding can slightly affect the fabric shrinkage. For elastic fabrics, excessive resting can lead to increased shrinkage and a narrower fabric width, particularly in weft-elastic fabrics.

In elastic or high-twist fabrics, uneven external forces during the stress release process may result in inconsistent fabric width after preshrinking or pre-setting. This inconsistency can cause issues in subsequent processes.

Therefore, it’s crucial to avoid prolonged storage of unwound polyester woven fabrics, especially for stretch varieties, to maintain uniform width during the entire production process.

By controlling these factors, manufacturers can achieve consistent width in finished fabrics and ensure quality throughout the production workflow.

② Scouring

Scouring can be performed in rope form or open-width form.

Rope scouring is a standard pretreatment process for regular polyester woven fabrics, aiming to remove impurities without affecting subsequent processing quality. Key process parameters include heating rate, maximum temperature, auxiliary concentration, and dwell time.

As a thermoplastic fiber, polyester undergoes changes under moist heat. The higher the temperature and heating rate, the more pronounced these changes become. To minimize these effects, the scouring temperature is kept below the glass transition temperature of polyester fibers.

Therefore, rope scouring has minimal impact on the finished width of regular plain polyester woven fabrics.

For stretch fabrics, particularly those with weft stretch or dual stretch, open-width scouring is essential to effectively control fabric width shrinkage. This process is carried out using an open-width scouring machine equipped with multiple washing compartments that offer varying scouring temperatures—starting with cold water and gradually increasing to warm water.

During scouring, the fabric is gently stretched to evenly reduce width shrinkage by over 20%. This gradual and uniform shrinkage ensures a smooth fabric surface, which is critical for achieving high-quality finishes. Open-width scouring at low temperatures is a simple yet effective method to achieve uniform shrinkage in polyester stretch fabrics, preventing wrinkles during subsequent processing.

For wide-width plain stretch fabrics, open-width scouring eliminates internal stress, maintaining dimensional stability. If the width shrinks excessively, the machine speed can be reduced. For instance, a fabric with a loom width of 210 cm typically shrinks to around 180 cm after scouring. If the width exceeds 160 cm post-scouring, the processing speed is likely too high.

③ Preshrinking

Preshrinking is conducted in rope form at temperatures higher than those used in scouring but lower than those for dyeing.

This high-temperature, moist heat pretreatment not only removes starch, oil, and other impurities but also helps release internal stress, resulting in gradual fabric shrinkage. Under such conditions, highly crystalline regions within fibers undergo disorientation, while less crystalline regions experience orientation.

This results in a balanced degree of orientation across the fiber, enhancing dimensional stability and producing a smoother, more stable fabric width. The preshrinking process for polyester woven fabrics is similar to the mercerization of cotton fabrics.

During preshrinking, the warp yarns experience greater tension due to the pulling force from the dyeing machine's nozzles, while the weft yarns encounter relatively less stress. The result is more significant weft shrinkage compared to warp shrinkage. The interaction between warp and weft yarns during high-temperature shrinkage further balances fabric width and length.

For instance, as the thicker weft yarns shrink, they compress the warp yarns, and vice versa, resulting in a final width and length that align with design specifications. Understanding the shrinkage behavior of different yarn twists, materials, and fabric structures is fundamental to designing fabrics with stable finished widths.

During the preshrinking process, the greater the nozzle tension, the more significant the fabric width reduction. A nozzle with too small an aperture can hinder the smooth passage of fabric through the nozzle, potentially causing fabric damage and resulting in uneven shrinkage.

Conversely, if the nozzle aperture is too large and the nozzle tension is excessively high, fabrics without selvage structures are prone to edge distortion, which can complicate subsequent processing and final setting.

While increasing the cylinder temperature can help alleviate edge distortion, excessively high water temperatures during preshrinking can cause uneven shrinkage of the fabric.

Gradual temperature increases and maintaining heat at different stages during the preshrinking process are key strategies for extending processing time and moderating the conditions, especially for high-twist fabrics. Prolonged processing time and softened conditions contribute to more pronounced shrinkage effects. Uniform shrinkage, dimensional stability, and a smooth fabric surface are essential quality indicators for the preshrinking process. Sometimes, after preshrinking, high-twist fabrics may have excessive width or exhibit surface splitting, which results from improper process design.

By adopting a segmented temperature increase during the preshrinking process, it’s possible to reduce nozzle tension and lower fabric circulation speed. This adjustment allows for longer immersion time in the preshrinking bath, helping the fabric to shrink more effectively in a high-temperature, moist state. This approach enhances the preshrinking effect and ensures more uniform and stable results.

④ Pre-setting

Pre-setting is conducted on a stenter frame and is essentially a continuation of the preshrinking process for polyester woven fabrics.

Both processes aim to stabilize the fabric, but they differ in the medium used—preshrinking occurs under moist heat, while pre-setting is carried out under dry heat. The slow shrinkage achieved under moist heat needs to be consolidated and enhanced through pre-setting in dry heat.

Key parameters for pre-setting include temperature, width, tension, and machine speed. The pre-setting temperature is typically slightly higher than the final setting temperature to ensure better dimensional stability of the fabric.

The pre-setting width should be slightly narrower than the finished width. Increased tension during the pre-setting process tends to straighten the warp yarns, causing the weft yarns to become more curved, which may result in a slight reduction in the fabric width.

Machine speed, influenced by factors such as stenter length, fabric thickness, material type, and weave structure, also plays a crucial role in pre-setting efficiency.

The pre-setting width should be determined based on the width after preshrinking, the fabric’s flatness before pre-setting, and the desired finished width. Adjustments to the pre-setting width should not be excessive, nor should temperature fluctuations be too large, as this could lead to significant discrepancies in fabric width before final setting, making the finishing process difficult to execute properly.

⑤ Alkali Reduction

The purpose of alkali reduction is to thin the twisted polyester filaments. Thinner yarns have lower rigidity, allowing for greater movement between the yarns, which ultimately improves the fabric's hand feel.

After alkali reduction, the fabric becomes softer, and the width tends to slightly increase. This increase in width is closely related to the type of material and fabric structure, typically around 1 cm.

In dyeing, high-temperature alkali reduction results in a more pronounced increase in fabric width. However, washing the fabric after alkali reduction and before dyeing does not affect the fabric width.

⑥ Dyeing

Similar to preshrinking, the dyeing process also takes place under high temperature and moisture conditions.

However, the dyeing temperature is higher than that of preshrinking, marking the second stage of wet heat setting for the fabric. After the first stage of wet heat setting during preshrinking and the initial dry heat setting during the pre-setting process, the fabric width becomes largely stabilized. Although the dyeing temperature is approximately 10°C higher than the preshrinking temperature, the thermoplastic nature of polyester fibers, after high-temperature dry heat setting, results in a slight increase in fabric width during the dyeing process. This width increase is typically about 1 cm more than the pre-setting width.

The primary reasons for the increase in fabric width after reduction and dyeing are twofold. First, as the fabric circulates through the machinery, the process softens the fibers.

As the fibers soften, the movement between them becomes easier, which leads to a slight widening of the fabric. Second, under moist and heat conditions, the internal stresses induced by the preshrinking and pre-setting processes are released, causing the fabric to expand slightly.

⑦ Post-treatment

For ordinary fabrics, high-twist fabrics, and short-fiber faux wool fabrics, post-dyeing processes such as reduction washing and color fixing generally do not affect the fabric width.

However, for elastic fabrics, especially those with blended materials like weft elastic fabrics, excessive processing conditions can cause problems. For example, when cellulose fibers are dyed with sulfur dyes and then oxidized with agents, or when reactive dyes are used on cellulose fibers and fixed with soda ash, the process should not be overly harsh, and the processing time should not be too long.

Otherwise, excessive damage to the spandex elastic fibers can lead to a significant increase in fabric width, resulting in the final fabric width being too wide, with the loss of weft elasticity.

⑧ Dewatering, Relaxing, and Drying

The dewatering and relaxing processes after preshrinking and dyeing have minimal impact on the pre-setting itself. Relaxing, in this context, refers to the process of spreading the fabric flat—either manually or with equipment—without any winding, to facilitate drying or setting.

While the water content in the fabric after dewatering can affect drying efficiency, over-drying can cause new creases or other defects on the fabric surface. In most cases, to improve processing efficiency, conventional polyester woven fabrics can go directly into pre-setting after relaxing, skipping the drying stage, provided that the setting machine's drying chamber is sufficiently long to ensure the pre-setting effect.

Though both tumble dryers and tension dryers can influence fabric width during drying, the impact on fabric width after dyeing is much smaller than the effect from final setting.

For some specialty fabrics, such as bark cloth or pearl linen, a relaxed drying process is required to maintain the fabric’s unique texture. However, for most polyester woven fabrics, direct setting after relaxing is sufficient.

⑨ Final Setting

The final setting of ordinary polyester woven fabrics has the most significant impact on their dimensional stability. Whether it’s a regular fabric, high-twist fabric, faux wool short-fiber fabric, or elastic fabric, the final setting width is always based on the fabric’s width before setting.

While increasing the tension during the setting process can help narrow the fabric width, it is impossible to significantly reduce the width of fabric that was already too wide after dyeing. Similarly, fabric with a width too narrow after dyeing cannot be significantly widened during final setting, even with a dramatic reduction in tension.

The tension adjustment during final setting is even more crucial than during pre-setting. By adjusting the tension bar, tensioning device, spreading rollers, and overfeeding mechanism at the front of the setting machine, the tension during the final setting process can not only affect the fabric weight and hand feel, but also the final setting width.

For instance, after pre-shrinking with an elastic blanket machine, the width of T/C fabrics will increase moderately. After batch steaming of faux wool fabrics, the width also slightly expands. After water washing, the width of viscose short-fiber woven fabrics used as warp threads in denim-like weft-elastic fabrics will increase as well. Needle-board type setting machines are better at maintaining the longitudinal tension during final setting, which includes both positive stretching tension and negative pre-shrinking tension. In comparison, pad-type setting machines are less effective in this aspect.

The final fabric width does not solely depend on the set width after the finishing process, but rather on the inherent characteristics of the fabric and the entire dyeing and finishing process. With proper design and careful processing, the final width will truly reflect the fabric’s characteristics, ensuring stable dimensional stability.